Oncology Tumour Biology for Surgeons — Hallmarks, Sequence, MSI/Lynch/FAP, Angiogenesis, Metastasis, TNM, Grade, Margins, Markers, ctDNA, Sentinel, Neoadjuvant

The surgeon does not prescribe the chemotherapy and does not grade the slides — but the surgeon decides the margin, the nodal operation, the surveillance plan, and the moment to refer the polyposis family. Learn tumour biology as surgical doctrine: cancer develops through multistep accumulation of heritable changes in multiple genes; the hallmarks organize its capabilities; suppressors and oncogenes drive the adenoma-carcinoma sequence; mismatch repair defines Lynch and microsatellite instability; VEGF drives vessels and lymphatics; invasion runs through EMT and circulating cells; TNM records extent while grade records differentiation; R0 width changes survival; CEA guides without screening; prophylactic colectomy prevents near-certain cancer; liquid biopsy watches without replacing tissue; sentinel mapping stages with less harm; and combined modality beats single modality where surgery alone cannot eradicate.^{[1][5][18][19][26][31][36][41][42][48][58][61][69][74][50]}

A young adult with hundreds of rectocolonic adenomas, a colorectal cancer survivor with a rising CEA, a rectal cancer with a threatened margin, and a breast cancer with a clinically negative axilla sit on the same teaching list. The examiner will ask for the hallmark list and what underpins it, the gene classes and event count in multistep carcinogenesis, the adenoma-carcinoma order, what microsatellite instability marks and how to test it, the Lynch and FAP numbers with colectomy timing, how VEGF and EMT create metastasis, how TNM and Essential TNM work, how grade differs from stage, what margin width buys, what CEA can and cannot do, what circulating tumour DNA adds perioperatively, when sentinel biopsy replaces dissection, and why neoadjuvant therapy exists. This page answers each question with every statement taken from the paper named beside it.^{[2][7][13][21][27][33][38][44][46][49][55][70][52]}

Hallmarks — the Organizing Principle

The hallmarks comprise six biological capabilities acquired during multistep development of human tumours, and they constitute an organizing principle for rationalizing neoplastic complexity.^[1] They include sustaining proliferative signaling, evading growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, and activating invasion and metastasis.^[1] Underlying them are genome instability, which generates the genetic diversity expediting acquisition, and inflammation, which fosters multiple hallmark functions.^[1] Progress since added two emerging hallmarks of potential generality — reprogramming of energy metabolism and evading immune destruction — plus a further dimension: recruited ostensibly normal cells creating the tumour microenvironment that helps acquire hallmark traits.^[1]

The 2017 revisit keeps the seminal framing while reorganizing it into seven hallmarks: selective growth and proliferative advantage, altered stress response favouring survival, vascularization, invasion and metastasis, metabolic rewiring, an abetting microenvironment, and immune modulation.^[3] The 2021 new-testament review agrees the Hanahan-Weinberg distillation advanced therapeutics by targeting hallmarks, then proposes four further candidates from a decade of granularity — regression from specialized functional states, epigenetic change affecting expression, microorganisms, and neuronal signalling — with therapeutic-exploitation evidence attached.^[2] The count is not the examination point; the organizing use is.^[2][3]

Matrix and Microenvironment — the Scaffold That Signals

The extracellular matrix regulates tissue development and homeostasis, and its dysregulation contributes to neoplastic progression.^[4] It serves not only as the scaffold organizing tissues but provides biochemical and biomechanical cues directing cell growth, survival, migration and differentiation, and modulating vascular development and immune function.^[4] Genetic modification in tumour cells initiates and drives malignancy, yet cancer progresses within a dynamically evolving matrix modulating virtually every behavioural facet of tumour and stromal cells.^[4] Prevention and therapy therefore require understanding the reciprocal feedback between evolving matrix, tumour cells and associated stroma — matrix awareness, not matrix resection, is the surgeon-facing lesson.^[4]

Multistep Carcinogenesis — Initiation, Promotion, Progression

Many chemical exposures raise tumour incidence in animals and humans only after a long interval, and both the breadth of agents and the delay are explained by a multistep and multigene model: a normal cell evolves into a cancer cell through heritable changes in multiple independent genes.^[5] The two-stage initiation-plus-promotion paradigm showed chemicals act by qualitatively different mechanisms, but carcinogenesis is now recognized as more complex than initiation plus promotion; even the operationally definable three-stage initiation, promotion and progression does not adequately describe it.^[5] Recent evidence suggests 3 to 10 genetic events in common adult human malignancies, involving two distinct gene classes — proto-oncogenes and tumour-suppressor genes — with multiple oncogenes activated and multiple suppressors inactivated in the same tumour, by point mutation, translocation, deletion, amplification and numerical chromosome change, plus epigenetic heritable alteration and clonal expansion of altered cells.^[5] Mechanism classification, including genotoxic versus nongenotoxic grouping, is never exhaustive or definitive, and most carcinogens combine mechanisms that may vary by target tissue.^[5]

Carcinogenesis is a multistep process by which normal cells acquire genetic and epigenetic changes resulting in cancer, with host susceptibility and environmental exposure joined by a procarcinogenic microbiota role.^[6] In colorectal cancer three microbes illustrate the stages consistently: colibactin-producing Escherichia coli initiates DNA damage, enterotoxigenic Bacteroides fragilis promotes tumorigenesis through toxin-induced proliferation and tumour-promoting inflammation, and Fusobacterium nucleatum enhances progression through the Fap2 and FadA adhesins promoting proliferation and antitumour immune evasion with possible metastatic contribution.^[6] Defining mechanisms by stage is presented as essential for microbiota-targeted diagnosis, prognosis and treatment — stepwise thinking the surgeon already uses for adenoma management.^[6]

Oncogenes, Suppressors and p53 Context

TP53 reviews frame the suppressor from molecular features with therapeutic opportunities through to clinical investigation, and the context review places p53 function in tissue, stress and network state rather than as a standalone determinant.^[8][9][10] The viva discipline follows: quote TP53 biology at principle level and fence variant-level precision decisions to genetics, since this topic claims no variant-specific operative rule from these reviews.^[8][9][10]

Adenoma-Carcinoma Sequence — Crypts to Cancer

Colorectal cancer develops through progressive accumulation of mutations and epigenetic alterations in tumour-suppressor genes and oncogenes, and early events begin in normal crypts with clonal dynamics now mapped into tumorigenesis.^[7][16] The molecular-genetics reviews trace the same sequence through early colorectal cancer including nonpolypoid superficial lesions, with the order of molecular genetic events in tumorigenesis stated as a sequence rather than a single hit.^[12][14][17] Sporadic BRAF and KRAS mutations contribute during pathogenesis with endosome-lysosome biology in the spotlight, and the crypts-to-cancer synthesis keeps the holistic frame against single-gene reductionism.^[15][11] The surgeon-facing use is pathway awareness plus adenoma clearance and surveillance logic; polypectomy technique and site-specific management stay fenced to endoscopy and colorectal-cancer topics.^[13][11]

Epigenetics — Methylation, Histone, Non-coding RNA

Epigenetic modifications fundamentally regulate gene expression through DNA methylation, specific histone modifications and non-coding RNA interventions, with many genes' methylation status mapped during colorectal carcinogenesis and functions in initiation and progression being clarified.^[7] Histone-modification patterns in colorectal cancer remain less known, while deregulation of non-coding RNAs and their biogenesis genes is described in tumour progression with dysregulated microRNA examples in colorectal cells.^[7] Folate illustrates the humility: it feeds the main DNA methylating agent S-adenosylmethionine via 5-methyltetrahydrofolate in methionine synthesis, yet whether it protects against or promotes colorectal cancer by condition remains debated.^[7] Epigenetic marks are therefore presented as extremely promising tools for diagnosis, prognosis and therapy development — tools to watch, not tests this topic orders.^[7]

MSI and Defective Mismatch Repair — Definitions and Testing

Cancers with a defective DNA mismatch repair system contain thousands of mutations most frequently in monomorphic microsatellites and are thereby defined as having microsatellite instability, so microsatellite instability is a marker of defective mismatch repair.^[19] Detection runs on immunohistochemistry for loss of mismatch repair proteins and on molecular tests showing microsatellite alterations, and together with tumour mutational burden and PD-1 and PD-L1 expression it acts as a predictive biomarker for immunotherapy.^[19] The ESMO consensus process defines the microsatellite, instability, repair and MSI-tumour-feature terms, then recommends immunohistochemistry for MLH1, MSH2, MSH6 and PMS2 as the first action to assess microsatellite instability and defective repair, with strong agreement.^[19]

Lynch syndrome is among the most prevalent hereditary cancer syndromes, accounting for some 3 percent of unselected colorectal or endometrial cancers and 10 to 15 percent of mismatch-repair-deficient tumours, with recent molecular-pathogenesis advances carrying direct clinical-management implications.^[18] Reviews track recent Lynch advances, clinical aspects of mismatch-repair gene mutations, gastroenterology recognition and referral, microsatellite instability in colorectal cancer across two decades, and shared mutated neoantigens in Lynch colorectal neoplasia for immunoprevention awareness.^{[20][22][23][24][21][25]} Immunotherapy has revolutionized treatment of advanced mismatch-repair-defective cancers, with accumulating epidemiologic, clinical and molecular information moving toward genotype- and immunologic-subtype-specific surveillance, prevention and treatment — regimens themselves fenced to immunology and disease topics.^[18]

FAP — Recognition, Numbers, Flags

Familial adenomatous polyposis is characterized by many tens to thousands of rectocolonic adenomas developing during the second decade of life.^[60] Birth incidence is about 1 in 8,300 with equal sex distribution, accounting for under 1 percent of colorectal cancers, and European Union prevalence is estimated at 1 in 11,300 to 37,600.^[60] Most patients stay asymptomatic for years until adenomas grow large and numerous causing rectal bleeding or anaemia, or cancer develops — generally starting a decade after polyp appearance — with constipation or diarrhoea, abdominal pain, palpable masses and weight loss as nonspecific flags.^[60] Extraintestinal manifestations include osteomas, dental abnormalities such as unerupted or absent teeth with cysts and odontomas, congenital hypertrophy of the retinal pigment epithelium, desmoid tumours, and extracolonic cancers of thyroid, liver, bile ducts and central nervous system.^[60] Attenuated FAP runs milder with usually 10 to 100 polyps, later adenoma appearance and lower cancer risk.^[60] The adolescent-polyposis plus desmoid, osteoma, dental or retinal-pigment flag is a genetics referral, not a lesion-by-lesion surgical plan.^[60]

Prophylactic Colectomy — Rationale, Indications, Controversies

Discerning hereditary colorectal cancer genetics enables individualized prevention and treatment for patients and families, and because some syndromes carry nearly 100 percent colorectal cancer risk, prophylactic colectomy is an important cancer-preventing option whose rationale, indications and surgical-management detail the reviews address.^[61] Genetics drives timing and extent of surgery in inherited colorectal cancer syndromes, with dedicated reviews on prophylactic colectomy in hereditary nonpolyposis cancer, preventive surgery across FAP and hereditary nonpolyposis syndromes, and clinical, genetic and therapeutic aspects of FAP and HNPCC.^{[62][63][64][65]} Practical colorectal cancer genetics and hereditary-syndrome management-strategy reviews complete the referral frame.^[67][68] Controversies in operating on FAP and Lynch syndrome persist around timing and extent, so the defensible viva position is shared decision-making with genetics rather than a default named procedure — IRA, pouch and extended-resection choice stays fenced to colorectal-cancer topics.^[66]

Angiogenesis and Lymphangiogenesis — VEGF Logic

Vascular endothelial growth factor signaling critically regulates vasculogenesis, angiogenesis and lymphangiogenesis vital to vascular and lymphatic development, tissue repair and homeostasis, with ligands and receptors orchestrating endothelial proliferation, migration and survival in dynamic remodelling.^[26] Dysregulated signaling drives tumour angiogenesis among other pathologies: excess activity promotes tumour growth, invasion and metastasis, while insufficient signaling impairs wound healing and ischaemic disease response.^[26] Targeted agents including monoclonal antibodies and tyrosine kinase inhibitors revolutionized care of pathological angiogenesis — named here as therapeutic context, with prescribing fenced to pharmacology and disease topics.^[26]

Tumour angiogenesis stands as a hallmark capability, and vascularization runs through sprouting angiogenesis and beyond rather than sprouting alone.^[27][28] Co-receptor neuropilins add a regulatory layer across tumour angiogenesis and lymphangiogenesis with targeted-therapy strategies under study, and VEGF-D carries emerging human-disease roles — both as awareness rather than bedside selection criteria.^[29][30]

Metastatic Cascade — Steps, Routes, Circulating Cells

Metastasis is presented as the most complex and deadly event, with invasion at the tumour-stromal interface running as single-cell or collective migration — collective less common but more efficient.^[36] Initiation relies on tumour-stromal cross-talk plus epithelial-mesenchymal transition in single cells and hybrid transition in collective cells, with abnormal leaky vasculature and cross-talk facilitating intravasation as circulating tumour cells.^[36] Survival after detachment exploits metabolic rewiring to new-environment sources, anoikis avoidance off matrix, and flow-mechanics adaptation.^[36] Tumour hypoxia interacts with circulating cells in the same cascade.^[37] The cascade organizes margin, nodal and distant logic for the surgeon; systemic therapy and per-patient prediction rules are not claimed from these reviews.^[36][37]

EMT and Plasticity — Partial States Win

Epithelial-mesenchymal transition is a developmental program enabling stationary epithelial cells to migrate and invade as single cells, which tumour cells reactivate for partial epithelial loss and partial mesenchymal gain.^[31] Understanding of its contribution to invasion, migration and metastatic outgrowth evolved across cell lines, mouse tumour models and human breast tissues.^[31] Through the circulating-cell prism, transition biology explains how cancer spreads in blood, with biological and clinical importance stated for circulating cells and microenvironment contribution from transitioning cells.^{[33][38][35][34]} The colorectal systematic review extends the same program to colorectal metastasis.^[32] Hybrid epithelial and mesenchymal phenotypes are framed as fittest for metastasis, with emerging plasticity paradigms continuing the synthesis — principle-level awareness with no hybrid assay ordered from this topic.^[39][40]

TNM — the Standard, Its Keepers, Its Registry Shadow

The standard for assessing and recording tumour extent, necessary for most malignancies, is the Tumour Node Metastases classification, defined by the Union for International Cancer Control committee since the early 1950s and updated with the American Joint Committee on Cancer, the International Association for the Study of Lung Cancer and the International Federation of Gynecology and Obstetrics as knowledge, imaging, pathology and therapy advance.^[41] The 9th edition of the UICC classification was recently published, summarizing 8th-to-9th changes with head-neck and lung focus and described, referenced evidence basis.^[41] The Global Consultation review makes consistent understanding and use of staging itself an objective, promoting common expectations across users.^[43] Breast TNM and AJCC 8th-edition breast updates illustrate edition change in practice and are quoted here only for staging-logic awareness, with site-specific cutoffs fenced to disease topics.^[44][45]

Where full TNM is absent, Essential TNM offers registries a simplified alternative: accurate extent-at-diagnosis information matters for prognosis and cancer-control evaluation, yet collection remains challenging in high-income and low- and middle-income countries alike.^[42] Essential TNM stages the most advanced disease form in metastasis, then node, then tumour size or extension order, with flowcharts and rules for breast, cervix, prostate and colon combining into stage groups I through IV matching full-TNM groups and comparable to UICC groups.^[42] It serves population registries under Global-Initiative goals rather than individual operative decisions.^[42]

Grade Versus Stage — Differentiation Is Not Extent

Grade describes differentiation and stage describes extent, and prognosis needs both — a distinction the viva probes directly.^[46][47] Prostate grading and the ISUP bladder consensus on mixed-grade, invasive, subtype, divergent-differentiation and non-urothelial reporting show how specialties standardize grading process, and they are quoted here only for that standardization lesson.^[46][47] No tumour is graded in this topic; microscopic grading and grade-specific management belong to pathology and disease topics.^[46][47]

R0 Doctrine — Width, Distance and Honesty

Negative resection margin is considered of paramount importance for prognosis in colorectal liver metastases, yet optimal width remains controversial — the background the Ann Surg meta-analysis set out to resolve.^[48] Across 34 studies and 11,147 hepatic resections, wider margin above 1 cm versus below 1 cm improved overall survival at 3, 5 and 10 years with pooled relative risks 0.86, 0.91 and 0.94, and disease-free survival moved the same way; even above 1 mm versus below 1 mm improved overall survival at all time points.^[48] Pursue R0 with measured clearance and report distance — the width-matters principle with its controversy intact.^[48]

The pancreatic meta-analysis brings the same discipline with different numbers: curative resection is the only chance of cure yet margin-status effect stayed contested under non-standardized pathology and varying R1 criteria.^[49] Across 8 retrospective studies and 1,932 patients with involved margin, clearance up to 1 mm, and clearance above 1 mm, survival stratified stepwise — above 1 mm beat up to 1 mm with hazard ratio 0.74, which beat involved margin with hazard ratio 0.81, without between-study heterogeneity.^[49] Stratify patients by margin status and state the retrospective limits; re-resection and adjuvant consequences stay fenced to pancreatic and HPB topics.^[49]

Tumour Markers — CEA Doctrine and Limits

CEA is a complex glycoprotein produced by 90 percent of colorectal cancers contributing to malignant characteristics, quantitatively measurable in serum as a disease marker.^[58] For lack of early-stage sensitivity it is unsuitable for population screening.^[58] Elevated preoperative CEA is a poor prognostic sign correlating with reduced overall survival after resection, and failure to return to normal after resection indicates inadequate resection of occult systemic disease.^[58] Frequent postoperative monitoring may identify metastatic patients for whom resection or localized therapy could help, with serial measurement outperforming clinical evaluation or other modalities — most sensitive for liver metastasis, less so for locoregional or pulmonary recurrence — and a small CEA-directed-salvage fraction alive and disease-free at 5 years.^[58] Clinical marker use in oncology carries the same general-limits framing in the older Jacobs review.^[54]

The meta layer quantifies both signal and delivery gap. Elevated postoperative CEA across 20 studies and 10,114 patients associates with worse overall survival with hazard ratio 2.92, worse disease-free survival at 2.81, and worse recurrence- or progression-free survival at 2.52.^[59] Yet adherence across 14 studies and 55,895 resected patients runs highest for colonoscopy at 70 percent, then imaging at 63 percent, then CEA at 54 percent, with American Society of Clinical Oncology-subset compliance at 73, 58 and 45 percent respectively and markedly lower CEA than colonoscopy adherence in colon and rectal subgroups.^[55] Metastatic colorectal marker reviews and circulating-DNA-plus-CEA-plus-imaging surveillance comparisons extend the same pairing lesson: CEA rides with colonoscopy and imaging, never alone.^[57][56]

Circulating Tumour DNA — Surgeon Awareness, Not Ordering

During progression and treatment, competing subclonal populations face selective pressure leaving predominant subclones that replicate, spread and resist treatment most proficiently.^[69] Solid-tumour molecular landscapes from surgical or biopsy tissue suffer sampling bias, snapshot heterogeneity and non-repeatability, while circulating cell-free tumour DNA genomic profiles closely match corresponding tumours with implications for pathology and oncology.^[69] Liquid biopsies analysing circulating nucleic acids monitor treatment response, emerging resistance and minimal residual disease, with tumour-derived genetic information also present in urine, saliva, pleural fluid and cerebrospinal fluid, complemented by circulating cells, RNA, proteins and vesicle lipids such as exosomes.^[69]

The Surgeon review brings this perioperatively: liquid biopsy components are circulating nucleic acids, circulating tumour cells and extracellular vesicles including exosomes, with cell-free and circulating tumour DNA the recent focus for screening, prognostication and genomic profiling without repeated tissue biopsy.^[70] Recent evidence shows perioperative liquid biopsy stratifying recurrence risk against conventional biomarkers, with perioperative dynamics potentially illuminating surgery-cancer-outcome relationships — awareness to discuss at multidisciplinary meetings, with assay ordering and colorectal liver-metastasis and rectal ctDNA meta-analytic detail fenced to disease topics.^{[70][71][72][73]}

Sentinel Logic — Stage More, Dissect Less

Axillary status is the single most important prognostic indicator of overall survival in breast cancer, with staging built on tumour size and nodal metastasis while node count, though prognostic, no longer changes treatment options.^[74] Sentinel mapping and dissection stages axillary nodes more sensitively and accurately than dissection alone while carrying less surgical morbidity and supplying prognostic information.^[74] Under experienced pathology with serial sectioning and immunohistochemistry it is the most accurate breast-staging detection tool, and in many centres using these principles dissection is no longer performed for histologically negative sentinel nodes.^[74] In most patients the sentinel node is the only positive axillary node, which can make the technique therapeutic as well as diagnostic.^[74] Biopsy is justified in high-risk ductal carcinoma in situ such as large tumours, masses or high-grade lesions, and in neoadjuvant chemotherapy it evaluates the axilla accurately in 90 percent of cases.^[74] Melanoma staging principles extend the same mapping logic to a second disease, quoted here for logic only with melanoma care fenced out.^[75]

Neoadjuvant and Combined Modality — Principle Level

The three established cancer-treatment modalities are operative surgery, radiotherapy and chemotherapy, historically delivered by separate discipline experts recommending one modality or another.^[50] Where single-modality results disappointed, planned integration of two or three modalities improved outcomes, and surgical oncology developed as combined treatment with chemotherapy or radiotherapy or both rather than operation alone.^[50] For advanced but localized cancers where operation alone is unlikely to eradicate tumour, or only through mutilation such as amputation, reducing size and viability with chemotherapy first — induction or neoadjuvant treatment — renders many tumours more susceptible to total eradication by later radiotherapy or operation.^[50] General chemotherapy principles and curative-chemotherapy framing support the same combined thinking, with localized-pancreas guiding principles quoted only for principle endpoints and all regimens fenced to disease and pharmacology topics.^[51][52][53]

Exam Synthesis and Fence Map — What This Topic Owns

This topic owns surgeon-facing tumour biology: hallmark capabilities with matrix and microenvironment; multistep initiation, promotion and progression with 3-to-10-event, two-gene-class discipline; TP53 and suppressor-versus-oncogene logic; adenoma-carcinoma sequence with crypt dynamics and KRAS and BRAF awareness; epigenetic methylation, histone and non-coding-RNA mechanisms with folate humility; mismatch-repair, microsatellite-instability and Lynch testing with 3-percent and 10-to-15-percent anchors; FAP recognition with 1-in-8,300, under-1-percent, decade-later and 10-to-100 attenuated numbers plus extraintestinal flags; prophylactic-colectomy rationale at near-100-percent risk with controversy-honest timing; VEGF vasculogenesis, angiogenesis and lymphangiogenesis logic with sprouting-and-beyond plus neuropilin and VEGF-D awareness; single-versus-collective invasion with stromal cross-talk, leaky intravasation, metabolic, anoikis and flow survival plus hypoxia; EMT partial-state and hybrid-fittest plasticity; UICC TNM since the early 1950s with AJCC, IASLC and FIGO updating to a recent 9th edition plus Global-Consultation consistency and Essential-TNM I-through-IV registry shadow; grade-versus-stage separation with consensus-process examples; R0 width and distance doctrine from 11,147 liver and 1,932 pancreas resections; CEA 90-percent production with screening-unsuitable, poor-prognosis, failure-to-normalize and serial-monitoring doctrine plus 2.92, 2.81 and 2.52 meta-analytic hazards against 70, 63 and 54 percent adherence; circulating-DNA tissue-matching with response, resistance and residual-disease monitoring plus perioperative recurrence-stratification awareness; sentinel more-sensitive less-morbid staging with dissection omitted for negative nodes under expert pathology and 90-percent neoadjuvant accuracy; and three-modality induction and neoadjuvant shrinking for later eradication.^{[1][5][9][14][7][19][18][60][61][26][36][31][41][42][46][48][58][59][69][70][74][50]}

Site-specific staging cutoffs, operative choice, adjuvant regimens, assay ordering, immunotherapy prescribing, chemotherapy dosing, polypectomy technique, desmoid and thyroid operations, and re-resection decisions belong to colorectal-cancer, breast-cancer, gastric, pancreatic, oesophageal, liver, biliary, endoscopy, pathology, surgical-immunology and perioperative-pharmacology topics; fluids, acid-base, wound-healing, antimicrobials, nutrition, transfusion, massive-transfusion, DIC, shock, sepsis and multiorgan topics keep their own endpoints; this topic claims only the general principles above with the numbers named beside them.^{[13][17][21][25][45][49][53][56][57][75]}

Exam Pearls — the One-Liners That Score

• Hallmarks 2011: six capabilities plus genome-instability and inflammation underneath, two emerging (metabolism, immune evasion), recruited normal cells as microenvironment — organizing principle, not count.^[1]
• 2017 seven-hallmark revisit and 2021 four-candidate update (dedifferentiation regression, epigenetics, microbes, neuronal signalling) refine without replacing the frame.^[3][2]
• Matrix dysregulation modulates virtually every hallmark through growth, survival, migration, differentiation, vascular and immune cues.^[4]
• Multistep model: heritable multi-gene change, initiation-promotion-progression operational but incomplete, 3 to 10 events, activated oncogenes plus inactivated suppressors by five alteration types plus epigenetics and clonal expansion.^[5]
• Microbiota stepwise in CRC: colibactin E. coli initiates, enterotoxigenic B. fragilis promotes, F. nucleatum Fap2 and FadA progresses with immune evasion.^[6]
• CRC epigenetics: progressive mutation plus epigenetic accumulation, methylation plus histone plus non-coding RNA, folate protection-versus-promotion still debated.^[7]
• TP53 reviews plus p53-in-context: suppressor biology with therapeutic opportunities, never a standalone surgical trigger.^[8][10]
• Sequence: crypt clonal origins, early-cancer molecular order including nonpolypoid lesions, sporadic KRAS and BRAF contribution.^[16][14][15]
• MSI marks defective mismatch repair with thousands of monomorphic-microsatellite mutations; test MLH1, MSH2, MSH6 and PMS2 by IHC first, molecular confirmation where indicated, with TMB and PD-1 and PD-L1 as co-predictors.^[19]
• Lynch: some 3 percent of unselected CRC and endometrial cancers, 10 to 15 percent of repair-deficient tumours, genotype- and subtype-specific surveillance emerging, immunotherapy revolution in advanced defective disease.^[18]
• FAP: tens to thousands of second-decade adenomas, 1 in 8,300 births, under 1 percent of CRC, EU 1 in 11,300 to 37,600, cancers a decade after polyps, osteoma plus dental plus CHRPE plus desmoid plus extracolonic-cancer flags, attenuated 10 to 100 polyps with later lower risk.^[60]
• Prophylactic colectomy at near-100-percent syndrome risk with genetics-driven timing and extent and acknowledged timing-versus-extent controversy.^[61][62][66]
• VEGF regulates vasculogenesis, angiogenesis and lymphangiogenesis; excess drives growth, invasion and metastasis while insufficiency impairs healing and ischaemia; antibodies and kinase inhibitors in context; sprouting and beyond; neuropilins and VEGF-D as awareness.^{[26][28][29][30]}
• Cascade: single versus collective invasion (collective rarer more efficient), stromal cross-talk plus EMT or hybrid EMT, leaky intravasation as circulating cells, metabolic plus anoikis plus flow survival, hypoxia interaction.^[36][37]
• EMT partial loss plus partial gain, hybrid fittest, circulating-cell and microenvironment importance, colorectal extension.^{[31][39][38][32]}
• TNM standard since early 1950s with AJCC, IASLC and FIGO updates to recent 9th edition; Global Consultation for consistent use; breast TNM and AJCC-8th as edition-change examples only.^[41][43][44]
• Essential TNM: metastasis then node then tumour order into I through IV for breast, cervix, prostate and colon where full TNM absent, comparable to UICC groups for registries in high-income and low- and middle-income settings.^[42]
• Grade is differentiation, stage is extent; prostate and ISUP bladder consensuses illustrate standardization process only.^[46][47]
• Margins: 11,147 R0 liver resections favour above 1 cm (relative risks 0.86, 0.91, 0.94) with above 1 mm beating below 1 mm throughout; 1,932 pancreas resections stratify above 1 mm over up to 1 mm (hazard ratio 0.74) over involved (0.81).^[48][49]
• CEA from 90 percent of CRCs, serum-quantifiable, screening-unsuitable, preop elevation poor-prognosis, failure to normalize signals occult systemic disease, serial monitoring beats examination especially for liver recurrence, small salvage fraction disease-free at 5 years.^[58]
• Postop CEA hazards 2.92 overall, 2.81 disease-free, 2.52 recurrence- or progression-free across 10,114 patients; adherence 70 colonoscopy, 63 imaging, 54 CEA across 55,895 patients — pair CEA with scope and imaging.^[59][55]
• Circulating DNA matches tumours beyond snapshot bias, tracks response, resistance and residual disease across fluids plus vesicle cargo; periop dynamics stratify recurrence versus conventional markers as awareness.^[69][70]
• Sentinel mapping more sensitive and accurate with less morbidity, most accurate under serial sectioning plus immunohistochemistry, dissection omitted for negative sentinels, sentinel-only positivity common, high-risk in-situ and 90-percent neoadjuvant accuracy; melanoma logic extends the principle.^[74][75]
• Three modalities (surgery, radiotherapy, chemotherapy) integrated where single modality disappoints; induction and neoadjuvant shrinking enables later eradication including mutilation-sparing cases.^[50]

References75ShowHide

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