IM13.{1-4,15} | Oncology Foundations — Summary & Reflection

KEY TAKEAWAYS

Cancer epidemiology in India: tobacco (smoked and smokeless) drives oral, laryngeal, lung, and oesophageal cancers; HPV drives cervical cancer; HBV/HCV drive hepatocellular carcinoma; H. pylori drives gastric cancer. Breast cancer is the commonest female cancer in urban India. Inherited risk: BRCA1/2 (breast/ovarian), Lynch syndrome (colorectal/endometrial), FAP (colorectal).

Genetic basis: oncogenes activated by mutation, amplification, or translocation (RAS mutation, HER2 amplification, BCR-ABL1 translocation in CML → imatinib); tumour suppressor genes inactivated by two-hit mechanism (TP53 — guardian of the genome; RB1; APC; BRCA1/2). DNA MMR deficiency → MSI-H → responsive to immune checkpoint inhibitors.

Infection-related cancers: HPV 16/18 → cervical, anal, oropharyngeal cancer (E6 inactivates p53, E7 inactivates RB1); HBV/HCV → HCC; H. pylori → gastric adenocarcinoma and MALT lymphoma (cured by eradication in early stage); EBV → Burkitt lymphoma, nasopharyngeal carcinoma; KSHV → Kaposi sarcoma.

Natural history: CIS → invasive carcinoma → regional LN metastasis → haematogenous metastasis (lung, liver, bone, brain). Key oncological emergency: SVC obstruction (lung cancer/lymphoma compressing SVC — facial oedema, dilated chest veins, headache).

Prevention and screening: primary — tobacco cessation, HPV vaccine (9–14 yrs), HBV vaccine; secondary — VIA/Pap/HPV DNA for cervix, mammography/CBE for breast, FOBT for colorectal; tumour markers: AFP (HCC monitoring), CA 125, PSA (with counselling), CEA (monitoring not screening).

REFLECT

Consider Rajan from the opening case: his cancer was caused by a lifetime of tobacco and betel nut exposure, worsened by delayed presentation, and potentially compounded by an inherited susceptibility suggested by his sister's early breast cancer. Three separate prevention opportunities were missed: tobacco counselling at any earlier health contact, genetic risk assessment in the family, and potentially surveillance for early upper aerodigestive tract lesions. As a future clinician, how would you incorporate a cancer risk assessment into a routine outpatient consultation without it feeling like an interrogation? And when a patient like Rajan finally presents with an advanced cancer, how do you balance honest prognostication with preserving hope — the tension that will define many of your most challenging clinical conversations?