2.2.7: Cancer
Not started yet — this one needs some love.
Cancer: mutations (changes) in cells → uncontrolled cell growth and division.
Benign tumour: abnormal cells contained within a membrane; does NOT spread to other parts of the body; not cancer; can often be removed surgically.
Malignant tumour: cancer cells; invade neighbouring tissues; enter the bloodstream → travel to form secondary tumours (metastasis) elsewhere in the body.
Risk factors: lifestyle (smoking, UV radiation, ionising radiation, alcohol, obesity); genetic (inherited mutations that predispose to certain cancers).
Some cancers have identifiable carcinogens; others have primarily genetic risk factors.
Common exam mistakes
Benign ≠ cancer: benign tumours do NOT spread or metastasise; malignant tumours DO.
Secondary tumours form when cancer cells travel through the blood and establish new tumour sites elsewhere — not from the original tumour growing outward.
When discussing metastasis, refer to cancer cells forming secondary tumours (groups of cells) — references to individual cancer cells forming disease on their own are not credited.
'Tumour' alone is not sufficient — must specify benign or malignant (cancerous).