Targeted therapies block a specific molecular abnormality that drives a particular tumour's growth. Because they act on that abnormality rather than on all dividing cells, they usually cause less bone marrow suppression than chemotherapy — though they have their own side effects.
Common targets and where they occur
- EGFR, ALK and ROS1 — non-small cell lung cancer
- HER2 — breast and stomach cancer
- BCR-ABL — chronic myeloid leukaemia
- BRAF — melanoma and some other tumours
- VEGF pathway — colorectal, kidney and other cancers
- BRCA-related pathways — ovarian, breast, pancreatic and prostate cancer
Why testing comes first
These drugs are prescribed only when the relevant mutation or protein is demonstrated on tissue or blood testing. Without the target, the drug offers no benefit and still carries cost and side effects. Where tissue is limited, a liquid biopsy on a blood sample can sometimes provide the answer.
What treatment looks like day to day
Many targeted therapies are oral tablets taken at home, with clinic review every few weeks and periodic scans. Side effects commonly include skin rash, diarrhoea, mouth soreness, hand-foot reactions, blood pressure changes or altered liver function — usually manageable with dose adjustment and supportive care.
Resistance and what happens next
Cancers can develop resistance to a targeted drug over time. Repeat biopsy or liquid biopsy can identify the resistance mechanism, and for several cancers a second- or third-generation drug is then available. Progression on one targeted therapy does not mean options are exhausted.
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Medical disclaimer: This page is general health information, not medical advice. Cancer treatment decisions depend on your reports, stage and overall health. Please consult a qualified oncologist before acting on anything you read here.