Renal Cell Carcinoma

Meet the patient

A 62-year-old male smoker, BMI 33, on treatment for hypertension, has an ultrasound for vague right-sided discomfort that shows a 4.5 cm solid upper-pole renal mass. A multiphase CT confirms enhancement of 28 HU. His haematocrit is 0.54 and his corrected calcium 2.85 mmol/L. He has never seen blood in his urine.[1]

Three exam questions are now live, and you must answer them in order: what is this mass, what do the haematocrit and calcium mean, and why is chemotherapy not on the table? The whole topic is the answer.[1]

What RCC actually is — the 'internist's tumour' that hides on imaging

RCC is a heterogeneous group of adenocarcinomas of the renal tubular epithelium, and clear-cell is the dominant and most aggressive subtype. It makes up about 80 to 90 percent of all primary renal malignancies and roughly 2 to 3 percent of all adult cancers worldwide — the commonest primary kidney cancer.[1][8]

The clinical flavour is stealth. Most tumours are now found incidentally on imaging done for another reason, and the classic triad of haematuria, flank pain and a palpable flank mass appears in under 10 percent of cases — and usually spells advanced disease.[1]

RCC is the archetypal 'internist's tumour', and it earns the title three ways. It throws paraneoplastic syndromes (polycythaemia, hypercalcaemia, Stauffer syndrome); it invades the renal vein and climbs the IVC as tumour thrombus; and it is notoriously chemo-resistant (P-glycoprotein pumps, low proliferative index), which made it a grim diagnosis before the targeted-therapy era.[2]

Two clinical skills decide an RCC answer. First, recognise the solid enhancing renal mass as RCC until proven otherwise and stage it. Second, choose between curative surgery for localised disease and immunotherapy/TKI combinations for advanced disease, stratified by the IMDC score.[3][6]

Clear-cell, papillary, chromophobe — one gene per subtype

Learn the histological subtypes as 'one gene, one syndrome' — it is the highest-yield page in the topic. Clear-cell dominates; each of the others carries a single molecular signature and usually a hereditary counterpart.[1][9]

Hereditary RCC is the clean version of the sporadic disease — one syndrome, one gene, one subtype. A young patient with bilateral, multifocal tumours and a syndromic stigmata points you straight to the gene.[2][9]

SOAP plus dialysis and genes — who gets RCC

RCC is a cancer of affluence and imaging. GLOBOCAN 2020 counted roughly 431,000 new cases and 155,000 deaths a year worldwide; incidence is two to three times higher in men, peaks in the 6th to 7th decade, and is substantially higher in developed countries — partly an artefact of incidental detection on cross-sectional imaging.[8]

Recall the risk factors as SOAP plus dialysis and genes — every item is a viva mark.[1][8]

• S — Smoking. A dose-dependent relationship; smokers carry roughly 50 per cent higher risk than never-smokers, falling after cessation. The strongest single environmental risk factor.
• O — Obesity. Each 5 kg/m squared rise in BMI adds about 25 to 30 per cent risk, mediated by oestrogens, insulin-like growth factor-1, adipokines (leptin), lipid peroxidation and chronic inflammation. RCC is one of the cancers most strongly linked to obesity.
• A — Adult and older age. Peak incidence in the 6th to 7th decade.
• P — long-standing hypertension (H) and analgesic phenacetin abuse (historical). Hypertension is an independent risk factor; the association persists after adjusting for antihypertensive drugs.
• Dialysis and ESKD — acquired cystic kidney disease. After 3 to 5 years on dialysis, up to 90 per cent of patients develop acquired cystic change, with a 3- to 7-fold rise in RCC incidence; tumours are often multiple and arise in shrunken native kidneys.
• Genes and hereditary syndromes — see above; VHL is the prototype.
• Occupational and chemical exposures — cadmium, trichloroethylene, asbestos, petroleum products and chronic lead exposure are weakly associated.
• Race and geography — incidence is higher in North American and European populations; in India and many low- and middle-income countries RCC presents at a more advanced stage (less incidental detection).[8]

The VHL–HIF cascade — why RCC is golden, vascular and chemo-resistant

The molecular biology of clear-cell RCC is the best-understood of any solid tumour, and it directly explains every modern therapy. Learn the cascade once and the drugs write themselves.[2][9]

In health, VHL is the oxygen sensor's brake. The VHL protein (chromosome 3p25) is part of an E3 ubiquitin-ligase complex that, in normoxia, recognises and ubiquitinates the alpha subunit of hypoxia-inducible factor (HIF-1alpha and HIF-2alpha), tagging it for proteasomal degradation. HIF-alpha hydroxylation by prolyl hydroxylase (an oxygen-, iron- and 2-oxoglutarate-dependent enzyme) is the molecular signal of 'oxygen present' that lets VHL bind and destroy HIF.[1]

In clear-cell RCC, bi-allelic VHL loss takes the brake off — a textbook Knudson two-hit. One copy goes with chromosome 3p deletion, the second by point mutation or promoter hypermethylation. HIF-alpha accumulates even in the presence of oxygen, translocates to the nucleus, dimerises with HIF-beta, and drives a cassette of hypoxia-response genes:[2][9]

• VEGF and PDGF — drive the exuberant angiogenesis that makes RCC a golden-yellow, hypervascular tumour (and the target of every TKI).
• GLUT-1 and glycolytic enzymes — produce the Warburg effect (aerobic glycolysis) and the clear, lipid- and glycogen-laden cytoplasm that names the cell.
• Erythropoietin (EPO) — explains the paraneoplastic polycythaemia: the tumour arises in the very cell that physiologically regulates EPO.
• Carbonic anhydrase IX (CA-IX / G250) — a sensitive immunohistochemical marker of clear-cell RCC and a therapeutic target.
• TGF-alpha and EGFR ligands — autocrine growth stimulation.[1]

The other subtypes have their own one-line biology. Papillary type 1 is MET-driven (HGF-MET-RAF-MAPK, often chromosome 7 trisomy). Papillary type 2 (HLRCC) loses fumarate hydratase; fumarate accumulates, inhibits prolyl hydroxylases ('pseudohypoxia') and yields 2-succinocysteine — aggressive. Chromophobe loses multiple chromosomes (1, 2, 6, 10, 13, 17, 21) with FLCN loss in Birt-Hogg-Dube.[9]

Why RCC laughs at chemotherapy. Clear-cell RCC over-expresses P-glycoprotein (MDR-1 / ABCB1) multi-drug-resistance pumps, carries a low proliferative index, and is rich in detoxifying enzymes (glutathione-S-transferases). Cytotoxic chemotherapy is largely useless — which is exactly why targeted and immune-based therapies were built.[1]

Routes of spread — venous first is the RCC signature.[1]

1. Direct — through the renal capsule into perinephric fat and beyond Gerota fascia (T3 to T4).
2. Venous (the classic) — into the renal vein, then up the IVC as tumour thrombus, occasionally into the right atrium; may cause lower-limb oedema, Budd-Chiari physiology or pulmonary tumour embolism.
3. Lymphatic — to para-aortic, paracaval and retroperitoneal nodes.
4. Haematogenous — to lung (cannonball metastases), bone (osteolytic, expansile, pathological fracture), liver, brain and skin (rapidly growing vascular nodules).[1]

Paraneoplastic syndromes — E-P-Liver

RCC is the classic paraneoplastic cancer, and the trio to reproduce verbatim is E-P-Liver: Ectopic EPO, PTHrP, and the Liver (Stauffer). Each is an exam stem in disguise.[1][2]

The Stauffer pearl examiners love: it resolves after nephrectomy. That reversibility is the proof it is paraneoplastic, not metastatic — and a favourite single-best-answer discriminator.[1]

What you see at the bedside — the incidental mass and the two traps

The modern presentation is incidental: an asymmetric solid renal mass found on ultrasound or CT done for something else. Up to 50 to 60 per cent of RCCs are now diagnosed this way, and these tumours are typically smaller and at a lower stage.[1]

The classic triad — haematuria, flank pain, palpable mass — is now rare, and when all three coexist, assume advanced disease.[1]

• Haematuria — gross or microscopic, typically painless, from tumour erosion into the collecting system.
• Flank pain — capsular stretch, haemorrhage into the tumour, or clot colic.
• Palpable flank or abdominal mass — firm, non-tender, ballotable.[1]

The classic trap — a new left varicocele that does not empty on lying down. The left testicular vein drains into the left renal vein; a left renal tumour thrombus blocks it, raising a varicocele that stays full supine (a primary varicocele empties). Everyone forgets the right side: a right-sided varicocele is rare anatomically and points instead to IVC obstruction. Any new varicocele in a man earns a renal imaging study.[1]

The 'too-late' presentations that remain exam favourites:[1]

• Cannonball lung metastases with haemoptysis on a chest X-ray (differential: RCC, choriocarcinoma, sarcoma, occasionally thyroid).
• Pathological fracture from a lytic bone metastasis (rib, spine, pelvis, long bones).
• New-onset left varicocele that does not empty lying down (see the trap above).[1]

Systemic and B symptoms are themselves often paraneoplastic. Weight loss, fatigue, fever (RCC is in the differential of fever of unknown origin), night sweats, and anaemia disproportionate to disease stage (chronic inflammation, IL-6) all count as presentation features.[1]

Atypical presentations — drop your threshold in these groups.[1]

• Elderly — anaemia, weight loss, vague abdominal discomfort; the haematuria is dismissed and the mass blamed on 'constipation'.
• Dialysis and ESKD patient — a new mass in a shrunken native kidney, a falling EPO requirement (or, paradoxically, rising EPO), haematuria in an anuric patient.
• Pregnancy — incidental finding on obstetric ultrasound; management is tailored to gestation and risk.
• Hereditary syndrome patient (VHL) — known diagnosis, multifocal bilateral tumours from the second decade onwards; surveillance imaging drives detection.
• Young patient with sickle-cell trait — think renal medullary carcinoma, devastatingly aggressive.[1]

Bosniak — the cyst that hides a cancer

Not every renal mass is RCC, and not every cyst is benign — the Bosniak system is how you tell a cyst from a cystic cancer on CT. Reproduce the categories and their malignancy risks verbatim; it is a guaranteed mark.[1]

The discriminator that earns the mark: enhancement. A cyst that measurably enhances (Bosniak III or IV) is malignant until proven otherwise — biopsy or excise. No enhancement, no matter how complex-looking, stays in the follow-up (IIF) or no-follow-up (I, II) lane.[1]

The face-off — RCC versus its mimics

The complete differential of a renal mass, with the one feature that splits each from RCC.[1]

Renal mass biopsy — when to push the needle, when to leave it alone. Biopsy is indicated for metastatic disease before systemic therapy, for enrolling in active surveillance, for suspected lymphoma, infection or metastasis, and for syndromic or atypical tumours. It is avoided when imaging is classically malignant and the patient is going straight to surgery (the historical tract-seeding worry is now small but real).[1]

Multiphase CT and the 15 to 20 HU rule

Multiphase contrast CT of the abdomen and pelvis is the gold standard, and the 15 to 20 HU rule is the single number to remember. A solid mass that enhances by more than 15 to 20 HU between the non-contrast and contrast phases is RCC until proven otherwise.[1]

The first-line work-up of a confirmed or suspected renal mass:[1]

• Multiphase contrast CT abdomen and pelvis — phases: non-contrast (baseline density, about 20 to 40 HU), corticomedullary (early arterial), nephrogenic (parenchymal) and excretory (collecting system). It also defines size, renal-vein and IVC thrombus, nodal disease, and adrenal and liver involvement.
• CT chest (or chest X-ray) — for cannonball lung metastases.
• Full blood count, U and E, LFT, calcium, coagulation — anaemia, polycythaemia, the Stauffer pattern (raised ALP, abnormal PT, hypoalbuminaemia), hypercalcaemia, renal function.
• Urinalysis — haematuria; cytology if upper-tract urothelial carcinoma is suspected.
• MRI — when CT contrast is contraindicated (allergy, AKI, CKD, pregnancy), for detailed mapping of IVC tumour thrombus, and to characterise small indeterminate masses.
• Bone scan — only if bone pain, raised alkaline phosphatase or pathological fracture; not routine (RCC bone metastases are often osteolytic).
• Renal mass biopsy — see the face-off above.
• EPO level and PTHrP — selected cases to confirm a paraneoplastic syndrome.[1]

Examine the patient for the clues the scan will not give you.[1]

• Abdomen — bimanual ballottement: one hand anterior in the lumbar region, one posterior in the renal angle; on deep inspiration the kidney descends and is 'ballotted' between them. A normal right kidney is occasionally palpable in a thin patient; the left kidney is virtually never palpable unless enlarged. A renal mass is dull to percussion.
• Hands and face — plethora (polycythaemia), clubbing (paraneoplastic), leuconychia (hypoalbuminaemia, Stauffer).
• Chest — varicocele (especially left), pleural effusion, cannonball metastases.
• Abdomen — hepatomegaly (Stauffer or metastases), ascites, caput medusae (IVC obstruction).
• Lower limbs — oedema from IVC thrombus; deep-vein thrombosis (RCC is hypercoagulable).
• Spine and bones — tenderness at metastatic sites, neurological deficit (cord compression — an emergency).
• Skin — vascular cutaneous metastases; fibrofolliculomas (Birt-Hogg-Dube).[1]

Bedside assessment of severity. Vital signs, performance status (Karnofsky or ECOG), haemorrhagic shock (massive haematuria), hypercalcaemic crisis (dehydration, confusion, constipation), and cord compression (back pain, weakness, sensory level, urinary retention — a surgical and oncological emergency).[1]

Stage the tumour, score the patient — TNM and IMDC

Two frameworks drive an RCC answer: AJCC TNM for the localised tumour, and IMDC for the metastatic patient. Reproduce both.[1]

AJCC 8th edition TNM — the T stage hinges on size and on Gerota fascia:[1]

• T1a — 4 cm or less, limited to kidney.
• T1b — over 4 cm up to 7 cm, limited to kidney.
• T2a — over 7 cm up to 10 cm, limited to kidney.
• T2b — over 10 cm, limited to kidney.
• T3a — into the major renal vein, perinephric fat or renal sinus, not beyond Gerota fascia.
• T3b — into the vena cava below the diaphragm.
• T3c — into the vena cava above the diaphragm or its wall.
• T4 — beyond Gerota fascia (including ipsilateral adrenal).
• N0 / N1 — none / metastasis in regional nodes.
• M0 / M1 — none / distant metastasis.[1]

IMDC (Heng) prognostic score — six blood-and-history points that drive first-line choice in metastatic RCC. One point each:[3][6]

• Time from diagnosis to systemic therapy under 1 year.
• Karnofsky performance status under 80.
• Haemoglobin below the lower limit of normal.
• Corrected calcium above the upper limit of normal.
• Neutrophil count above the upper limit of normal.
• Platelet count above the upper limit of normal.[1]

Risk groups: favourable equals 0; intermediate equals 1 to 2; poor equals 3 to 6. The IMDC score (a refinement of the original Memorial Sloan-Kettering / Motzer score) is the central prognostic tool and decides the first-line regimen in metastatic RCC.[1]

Surgery cures the localised — resect, ablate, or watch

Localised RCC (T1 to T3, M0) is curable by surgery, and the choice is partial versus radical nephrectomy, with ablation and surveillance for the unfit.[1]

• Partial nephrectomy (nephron-sparing surgery) — preferred for T1 tumours (especially under 4 cm), a solitary kidney, bilateral tumours, chronic kidney disease and hereditary syndromes. Removes the tumour with a margin of normal parenchyma. Equivalent oncological outcome to radical nephrectomy for T1 tumours, with a lower risk of long-term CKD.
• Radical nephrectomy — for larger (T2) tumours, central tumours not amenable to partial, or when partial is technically infeasible. Removes the kidney, perinephric fat and Gerota fascia, with ipsilateral adrenalectomy when the upper pole is involved or the adrenal is directly invaded; hilar lymph-node dissection for staging.
• Minimally invasive (laparoscopic or robotic) — less pain, shorter stay, equivalent oncology, especially for T1 to T2 tumours.
• Thermal ablation — radiofrequency ablation and cryoablation for small (under 3 to 4 cm) tumours in elderly or unfit patients or those with multiple comorbidities; lower morbidity, higher local recurrence than surgery.
• Active surveillance — for small renal masses (under 2 to 4 cm) in patients with limited life expectancy; serial imaging with intervention if growth. Validated by the DISSRM registry.[1]

The immunotherapy revolution — CheckMate, KEYNOTE, CLEAR

Advanced and metastatic RCC is the poster-child of modern immuno-oncology — and cytotoxic chemotherapy has no meaningful role in it. High-dose IL-2 and interferon-alpha were the cytokine-era first lines; IL-2 can produce durable complete remissions in a small minority but is highly toxic and now largely superseded.[5]

Modern first-line combinations — agent, target, regimen, evidence. Reproduce the trial names; they are exam currency.[3][6][7]

The trials that built the field — know these by name.[3][4][5][6][7]

• Motzer 2007 — sunitinib versus interferon-alpha (NEJM) — the first targeted therapy to improve PFS and OS in metastatic RCC; the start of the TKI era.[5]
• CheckMate 025 (Motzer and Escudier, 2015, NEJM) — nivolumab (PD-1) versus everolimus after TKI failure; the first immune checkpoint inhibitor to improve OS in RCC.[4]
• CheckMate 214 (Motzer, 2018, NEJM) — nivolumab plus ipilimumab versus sunitinib first-line; superior OS in intermediate and poor-risk ccRCC; established dual ICI as first-line.[3]
• KEYNOTE-426 (Rini, 2019, NEJM) — pembrolizumab plus axitinib versus sunitinib; superior OS, PFS and response.[6]
• CLEAR (Motzer, 2021, NEJM) — lenvatinib plus pembrolizumab versus sunitinib; the strongest first-line OS and PFS benefit to date.[7]
• CARMENA — questioned routine cytoreductive nephrectomy in the immunotherapy era.
• DISSRM registry — validated active surveillance for small renal masses.[1]

Management by IMDC risk group — match the regimen to the score.[3][6][7]

• Favourable-risk (IMDC 0) — TKI monotherapy (sunitinib, pazopanib) or an ICI plus TKI combination (pembrolizumab plus axitinib); weigh ICI toxicity against the indolent biology.
• Intermediate and poor-risk (IMDC 1 to 6) — an ICI-based doublet first-line: nivolumab plus ipilimumab, pembrolizumab plus axitinib, or pembrolizumab plus lenvatinib are all current standards.
• Progression after ICI and TKI — switch TKI class (to cabozantinib), lenvatinib plus everolimus, or tivozanib.
• Non-clear-cell histologies — extrapolated regimens; enrol in a clinical trial where possible.[1]

Cytoreductive nephrectomy and metastasectomy — selective now, not routine. Removing the primary in the face of metastatic disease was a cytokine-era cornerstone. CARMENA showed sunitinib alone was non-inferior to nephrectomy followed by sunitinib in intermediate and poor-risk metastatic ccRCC, so nephrectomy is now reserved for fit patients with limited metastatic burden, good performance status, and a symptomatic primary or a heavy tumour thrombus. Metastasectomy of oligometastatic disease (a single lung lesion, a solitary bone metastasis) can give prolonged disease-free survival in selected patients.[1]

The time-critical scenarios — when RCC is an emergency

Most RCCs are managed electively, but four scenarios demand same-day action.[1]

Massive gross haematuria from a renal tumour. ABCDE, two large-bore cannulae, cross-match, IV resuscitation and transfuse for instability; a three-way catheter with bladder irrigation to prevent clot retention, and cystoscopic clot evacuation if needed. Selective renal artery embolisation (interventional radiology) is first-line to arrest bleeding in the unfit or as a bridge to surgery; palliative or emergency nephrectomy if embolisation fails or the tumour is resectable.[1]

Hypercalcaemic crisis (PTHrP-mediated). Aggressive isotonic saline (3 to 6 L over 24 hours) to restore volume and drive calciuria; IV bisphosphonate — zoledronic acid 4 mg IV over 15 minutes (or pamidronate 60 to 90 mg), onset over 2 to 4 days; denosumab 120 mg subcutaneously in refractory disease or renal impairment; calcitonin 4 to 8 IU/kg subcutaneously every 12 hours for a rapid but transient effect while the bisphosphonate works. Then treat the tumour.[1]

IVC tumour thrombus with embolic risk. Weigh therapeutic anticoagulation (LMWH preferred) against bleeding risk. Define the cephalad extent with MRI or contrast CT — Novick and Mayo levels: 0, renal vein only; 1, IVC under 2 cm above the renal vein; 2, IVC over 2 cm below the hepatic veins; 3, at or above the hepatic veins; 4, into the right atrium (needs cardiopulmonary bypass, often a combined cardiothoracic and urological operation). Pre-operative renal artery embolisation may reduce vascularity in large tumours.[1]

Metastatic spinal cord compression. Dexamethasone 16 mg orally or IV immediately, then 16 mg daily in divided doses; urgent whole-spine MRI within 24 hours; neurosurgical or orthopaedic opinion for decompression and stabilisation if there is instability, a single compressive site, or neurological deficit (especially if non-ambulatory at presentation); urgent palliative radiotherapy (RCC is radio-resistant, but radiotherapy relieves compression and pain); then treat the systemic disease.[1]

Von Hippel-Lindau, dialysis, sickle trait — the special patients

Von Hippel-Lindau disease — the 'canary in the coal mine' for VHL-HIF biology. Autosomal dominant, VHL on 3p25. Patients develop bilateral, multifocal clear-cell RCC alongside CNS and retinal haemangioblastomas, phaeochromocytoma, pancreatic neuroendocrine tumours and cysts, endolymphatic sac tumours, and epididymal or broad-ligament cystadenomas. Management is lifelong surveillance imaging from adolescence, nephron-sparing surgery for tumours over 3 cm, and genetic counselling and testing of relatives.[2][9]

RCC in ESKD and dialysis — acquired cystic disease. Long-term dialysis brings acquired cystic kidney disease and a 3- to 7-fold rise in RCC incidence — often multifocal, in shrunken native kidneys. Many centres screen native kidneys with annual or biennial ultrasound; native nephrectomy may be considered at transplantation.[1]

Sickle-cell trait — think renal medullary carcinoma. Young Black patients with haematuria: consider this devastatingly aggressive tumour, rapidly fatal, presenting with haematuria, flank pain and weight loss.[1]

Other special groups.[1]

• Pregnancy — MRI and ultrasound are the imaging of choice (avoid radiation and iodinated contrast where possible). For small, low-risk tumours found in pregnancy, active surveillance with definitive surgery post-partum is reasonable; large or symptomatic tumours may need surgery in pregnancy (second trimester preferred).
• Chronic kidney disease — lower threshold to screen native kidneys; nephron-sparing strongly favoured; consider native-kidney nephrectomy at transplantation for known tumours.
• Elderly and frail — active surveillance for small renal masses; ablation preferred when intervention is indicated; weigh competing mortality.
• Solitary kidney — partial nephrectomy strongly preferred; ablative options; discuss dialysis risk.
• IVC and atrial tumour thrombus — multidisciplinary planning with cardiothoracic and vascular surgery; cardiopulmonary bypass for atrial (level 4) thrombus.
• Anticoagulated patient — balance bleeding (renal mass, surgery) against thrombosis (IVC thrombus, malignancy); bridge peri-operatively with LMWH; avoid neuraxial procedures while anticoagulated.[1]

Complications and pitfalls

Local complications.[1]

• Renal-vein and IVC tumour thrombus — pulmonary embolism, Budd-Chiari physiology, lower-limb oedema, caput medusae; dictates surgical complexity.
• Local recurrence after nephrectomy (positive margins, T3 disease).
• Tumour haemorrhage — spontaneous bleed causing flank pain; Wunderlich syndrome (massive non-traumatic renal haemorrhage).
• Obstruction of the collecting system with clot or tumour, causing hydronephrosis.[1]

Distant and paraneoplastic complications. Cannonball lung metastases with haemorrhage or haemoptysis; pathological fracture (osteolytic, expansile); spinal cord compression (emergency); brain metastases (haemorrhagic, neurosurgical emergency); hepatic failure from massive liver involvement; hypercalcaemia (PTHrP); polycythaemia (EPO); Stauffer syndrome; AA amyloidosis (nephrotic syndrome); non-metastatic neuromyopathy.[1]

Treatment-related.[1]

• Post-nephrectomy CKD progression — a major reason partial nephrectomy is preferred for small tumours; protect residual function with ACE-inhibitor or SGLT2-inhibitor and BP control.
• Immunotherapy adverse events (irAEs) — pneumonitis, colitis, hepatitis, endocrinopathy (thyroiditis, hypophysitis, type-1 diabetes, adrenal insufficiency), dermatitis, myocarditis; manage with corticosteroids and hold the ICI when severe.
• TKI toxicities — hypertension (VEGF blockade), hand-foot skin reaction, hypothyroidism, proteinuria, cardiotoxicity (heart failure), diarrhoea, fatigue, hair depigmentation.
• mTOR-inhibitor toxicities — pneumonitis, hyperglycaemia, mucositis, hyperlipidaemia.[1]

Classic diagnostic pitfalls — each one is an exam question.[1]

• Assuming a complex cyst is benign — under-stage a Bosniak III or IV cyst.
• Missing an IVC tumour thrombus on pre-operative imaging (catastrophic at surgery).
• Over-biopsying a typical angiomyolipoma (diagnosed radiologically by fat).
• Failing to image the contralateral kidney in VHL and other syndromes.
• Missing synchronous metastases — always stage with a chest CT before surgery.
• Confusing renal medullary carcinoma (sickle-cell trait, young) with a more indolent tumour.[1]

Prognosis and surveillance

Five-year survival by AJCC stage — the numbers worth memorising.[1]

• Stage I (T1 N0 M0) — about 80 to 95 per cent (excellent after surgery).
• Stage II (T2 N0 M0) — about 70 to 80 per cent.
• Stage III (T3 or N1, M0) — about 50 to 70 per cent.
• Stage IV (any T, any N, M1) — historically about 10 to 15 per cent, rising toward 25 to 30 per cent and beyond with modern ICI combinations in selected groups.[3]

Predictors of poor outcome. High ISUP or Fuhrman nuclear grade and sarcomatoid differentiation; tumour necrosis and lymphovascular invasion; nodal or distant metastases; a high IMDC score; anaemia, hypercalcaemia, low Karnofsky, short time-to-treatment; venous tumour thrombus (level-dependent); and the aggressive non-clear-cell histologies (collecting-duct, medullary, HLRCC).[3]

Surveillance after curative nephrectomy. Driven by recurrence risk (stage, grade, histology, margins). History, examination and bloods (eGFR, FBC, LFT, calcium) at each visit; chest imaging (CXR or CT) and abdominal imaging (US or CT) scaled to risk — low risk, yearly for 3 to 5 years; high risk, CT abdomen and chest every 6 months for 3 years then annually to 5 years. Renal-function surveillance is essential for the solitary kidney.[1]

Regional and guideline deltas

EAU (European Association of Urology) 2024 and NCCN (US) 2024 broadly converge on ICI-based combinations first-line for intermediate and poor-risk metastatic ccRCC, with TKI monotherapy for favourable-risk disease or unfit patients. The AUA 2017 active-surveillance guideline codifies surveillance for small renal masses (cT1).[1]

India and LMIC patterns (NCI and ICMR registries). RCC presents at a more advanced stage (less incidental detection); access to ICI and TKI is variable, with cost a real constraint; sunitinib and pazopanib generics have improved affordability; interferon and IL-2 still appear in resource-limited settings.[8]

Controversies. Renal mass biopsy — historical avoidance (seeding) versus modern use in metastatic and surveillance settings. Cytoreductive nephrectomy in the immunotherapy era — selective rather than routine. Adrenalectomy at radical nephrectomy — increasingly omitted when the adrenal is radiologically normal (sparing does not compromise oncology). Surgery versus ablation versus surveillance for small renal masses — patient-centred.[1]

Exam pearls

The high-yield one-liners that decide a viva.[1]

• Any solid renal mass that enhances over 15 to 20 HU on multiphase CT is RCC until proven otherwise.
• RCC is an adenocarcinoma of the proximal convoluted tubule — not the collecting system (that is urothelial carcinoma).
• The classic triad (haematuria, flank pain, palpable mass) is rare (under 10 per cent) and indicates advanced disease.
• A new left varicocele that does not empty on lying down in a man equals a left renal tumour in the renal vein — image.
• RCC is the classic cancer that causes polycythaemia, via ectopic erythropoietin from the tumour cell itself.
• Cannonball metastases (well-circumscribed round lung lesions): differential is RCC, choriocarcinoma, sarcoma, occasionally thyroid.
• Clear-cell RCC equals chromosome 3p deletion and VHL loss; papillary type 1 equals chromosome 7 trisomy and MET; HLRCC equals FH; Birt-Hogg-Dube equals FLCN.
• Stauffer syndrome resolves after nephrectomy — the pearl that confirms its paraneoplastic nature.
• RCC is chemo-resistant (MDR-1 and P-glycoprotein); surgery cures local disease; ICI and TKI for advanced.
• First-line ICI combinations for intermediate and poor-risk: nivolumab plus ipilimumab (CheckMate 214), pembrolizumab plus axitinib (KEYNOTE-426), pembrolizumab plus lenvatinib (CLEAR).
• Bosniak III and IV cysts are managed as malignant; IIF requires follow-up imaging.
• Sunitinib (VEGFR TKI) is the textbook prototype targeted therapy for RCC — 4 weeks on, 2 weeks off.[5]
• Cytoreductive nephrectomy is selective in the immunotherapy era (CARMENA).

Ward-round test

Stem 1 — the incidental mass with a paraneoplastic twist. A 62-year-old male smoker, BMI 33, hypertensive, has an ultrasound for vague right-sided discomfort showing a 4.5 cm solid upper-pole renal mass; multiphase CT confirms enhancement of 28 HU. Haematocrit 0.54, corrected calcium 2.85 mmol/L, ALP raised with normal bilirubin. What is the diagnosis, what do the bloods mean, and why is chemotherapy not the plan?[1]

Stem 1 — incidental enhancing mass with paraneoplastic syndrome (answer)

This is clear-cell RCC — a solid mass enhancing over 15 to 20 HU on multiphase CT is RCC until proven otherwise. The raised haematocrit is paraneoplastic polycythaemia (ectopic EPO); the hypercalcaemia is PTHrP-mediated (and an IMDC prognostic factor); the raised ALP with normal bilirubin invites Stauffer syndrome (non-metastatic, reversible hepatic dysfunction that resolves after nephrectomy). Chemotherapy is not the plan because RCC is chemo-resistant (P-glycoprotein pumps, low proliferative index). For this localised tumour the next step is partial or radical nephrectomy, which is curative; stage with a CT chest first.[1][2]

Stem 2 — the varicocele trap. A 58-year-old man presents with a three-month history of a left varicocele that, unlike his previous one, does not empty when he lies down. He is otherwise well. What is the single investigation you must not delay, and why?[1]

Stem 2 — new left varicocele that does not empty lying down (answer)

Image the kidneys — multiphase contrast CT. The left testicular vein drains into the left renal vein, so a left renal tumour thrombus obstructs it and raises a varicocele that stays full supine (a primary varicocele empties). A new left varicocele that does not empty on lying down is RCC until proven otherwise. (A right-sided varicocele is anatomically rare and points instead to IVC obstruction.) This is a named trap and a classic exam stem.[1]

Stem 3 — the cyst decision. A 70-year-old woman has a 4.2 cm right renal cyst found incidentally. Multiphase CT shows multiple thickened septa with measurable enhancement but no solid nodular component. What Bosniak category, what malignancy risk, and what is the management?[1]

Stem 3 — Bosniak III cyst (answer)

This is Bosniak III — a thick-walled or septate cyst with measurable enhancement but no enhancing soft-tissue nodule. Malignancy risk is about 50 per cent, and management is biopsy or surgical excision (partial nephrectomy). The discriminator that earns the mark is enhancement: a cyst that enhances (Bosniak III or IV) is malignant until proven otherwise, whereas a complex but non-enhancing cyst (IIF) only needs serial imaging at 6, 12 and 24 months.[1]

Stem 4 — metastatic intermediate-risk disease. A 55-year-old with metastatic clear-cell RCC, IMDC score 2 (intermediate risk), good performance status, asks about first-line treatment. Name two current standard first-line regimens, their targets, and the trials that established them. Why is cytoreductive nephrectomy not automatic?[3]

Stem 4 — first-line ICI combinations for intermediate-risk metastatic ccRCC (answer)

For intermediate or poor-risk metastatic clear-cell RCC, first-line is an ICI-based doublet. Two current standards: nivolumab plus ipilimumab (PD-1 plus CTLA-4; CheckMate 214) and pembrolizumab plus lenvatinib (PD-1 plus VEGFR TKI; CLEAR); pembrolizumab plus axitinib (KEYNOTE-426) is equally acceptable. Cytotoxic chemotherapy has no role — RCC is chemo-resistant. Cytoreductive nephrectomy is not automatic in the immunotherapy era: CARMENA showed sunitinib alone was non-inferior to nephrectomy followed by sunitinib in intermediate and poor-risk disease, so nephrectomy is now reserved for fit patients with limited metastatic burden, good performance status, and a symptomatic primary or heavy tumour thrombus.[3][6][7]

Coverage self-check

If you cannot answer any ward-round stem from this page alone, re-read the matching section. The page is built to be self-sufficient for final-prof, NEET-PG, INICET, USMLE and PLAB questions on Renal Cell Carcinoma.[1]

References

1. [1]Hsieh JJ, Purdue MP, Signoretti S, et al. Renal cell carcinoma Nat Rev Dis Primers, 2017.PMID 28276433
2. [2]Jonasch E, Walker CL, Rathmell WK. Clear cell renal cell carcinoma ontogeny and mechanisms of lethality Nat Rev Nephrol, 2021.PMID 33144689
3. [3]Motzer RJ, Tannir NM, McDermott DF, et al. Nivolumab plus Ipilimumab versus Sunitinib in Advanced Renal-Cell Carcinoma N Engl J Med, 2018.PMID 29562145
4. [4]Motzer RJ, Escudier B, McDermott DF, et al. Nivolumab versus Everolimus in Advanced Renal-Cell Carcinoma N Engl J Med, 2015.PMID 26406148
5. [5]Motzer RJ, Hutson TE, Tomczak P, et al. Sunitinib versus interferon alfa in metastatic renal-cell carcinoma N Engl J Med, 2007.PMID 17215529
6. [6]Rini BI, Plimack ER, Stus V, et al. Pembrolizumab plus Axitinib versus Sunitinib for Advanced Renal-Cell Carcinoma N Engl J Med, 2019.PMID 30779529
7. [7]Motzer R, Alekseev B, Rha SY, et al. Lenvatinib plus Pembrolizumab or Everolimus for Advanced Renal Cell Carcinoma N Engl J Med, 2021.PMID 33616314
8. [8]Sung H, Ferlay J, Siegel RL, et al. Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries CA Cancer J Clin, 2021.PMID 33538338
9. [9]Linehan WM, Ricketts CJ. The Metabolic Basis of Kidney Cancer Cancer Discov, 2019.PMID 31088840