Breast cancer diagnosed in pregnancy — structured SAQ (15 marks)

(a) Diagnostic principles — triple assessment (3 marks)

One mark per principle, maximum three. ^[1][2]

• Triple assessment as outside pregnancy — clinical examination, imaging (ultrasound first-line; mammography acceptable with abdominal shielding of the case being reconsidered per modern guidance), and tissue sampling. Pregnancy changes the texture of the breast but not the workup.
• Core needle biopsy is the preferred tissue technique — FNA is less reliable in the gravid, lactating breast because of the cellularularity of normal pregnancy change.
• Pregnancy is not a reason to defer diagnosis — a persistent, dominant, discretely palpable mass in pregnancy is worked up immediately; the six-week delay in this case is the failure mode the question is testing.^[1]

(b) Surgical management and axillary staging (4 marks)

One mark per principle, maximum four. ^[2][5]

• Surgery is safe at any gestation — mastectomy or wide local excision can be performed in pregnancy. Anaesthesia in pregnancy is safe with left lateral tilt and capnography.
• Sentinel lymph node biopsy using 99mTc-labelled nanocolloid is the preferred axillary staging — the INCIP series (Han 2018) of 145 women showed a low axillary recurrence rate (0.7% isolated ipsilateral axillary recurrence at 48-month follow-up) comparable to non-pregnant women, with no neonatal adverse events.^[5]
• Blue dye is avoided because of the small risk of anaphylaxis and uncertain fetal safety.
• Radiotherapy is deferred to postpartum — when radiotherapy would be required during pregnancy, mastectomy is the preferred operation to avoid an inadequate operation. The decision between mastectomy and breast-conserving surgery accounts for the radiotherapy timing.

(c) Systemic therapy — chemotherapy, radiotherapy, endocrine, HER2-targeted (5 marks)

One mark per named agent or timing rule, maximum five. ^[2][4][6]

• Chemotherapy after the first trimester (guideline-endorsed). The first trimester is the malformation window because of organogenesis; anthracycline- and taxane-based regimens administered after the first trimester have not shown an excess of congenital malformation. The INCIP comparison of pregnant breast cancer patients treated with chemotherapy versus non-pregnant controls showed comparable outcomes.^[4]
• Stop most chemotherapy by 34 weeks to allow marrow recovery before delivery, with a treatment-free window of around three weeks before birth.^[6]
• Radiotherapy deferred to postpartum (as above).
• Tamoxifen is contraindicated for clinical use in pregnancy — stopped before conception, withheld until postpartum, with barrier contraception during treatment and for three months after stopping before attempting conception. An inadvertent exposure is not an automatic indication for termination — counsel and continue.^[7]
• Trastuzumab is avoided — associated with oligohydramnios, fetal renal injury, and a recognised risk of irreversible fetal renal damage. HER2-targeted therapy is typically deferred to postpartum.
• Checkpoint inhibitors are avoided in pregnancy because of fetomaternal immune-tolerance disruption; decisions made individually for metastatic disease.^[8]

(d) Multidisciplinary team, delivery timing, placental pathology (3 marks)

One mark per element, maximum three. ^[1][2]

• Multidisciplinary team — maternal–fetal medicine, medical oncology, surgical oncology, anaesthesia, neonatology, perinatal mental health, a pathologist, and the woman herself. The Advisory Board on Cancer, Infertility and Pregnancy provides a virtual on-demand tumour board for centres without local expertise.
• Delivery-timing rules — avoid planned delivery before 37 weeks unless medically indicated; stop most chemotherapy by 34 weeks for marrow recovery; aim for a treatment-free window of around three weeks before birth.
• Placental pathology in every case of cancer during pregnancy (guideline-endorsed) — the only way to detect placental metastasis, which (particularly for melanoma and lung cancer) is the signal that the neonate needs lifelong surveillance.^[2]