Cancer cells survive partly by switching off the immune cells that should destroy them. Checkpoint inhibitors — the most widely used class of immunotherapy — block that switch, allowing T cells to act again.
How it differs from chemotherapy
Chemotherapy attacks the tumour directly and works quickly. Immunotherapy works through the immune system, so responses can take longer to appear but may last considerably longer once achieved. Side effect profiles are also different: instead of hair loss and low counts, the main risk is immune-driven inflammation of healthy organs.
Cancers where it is commonly used
- Non-small cell lung cancer
- Kidney and bladder cancer
- Head and neck cancers
- Melanoma
- Certain lymphomas
- Tumours with high microsatellite instability, regardless of site
How eligibility is decided
Testing comes first. PD-L1 expression, MSI or MMR status and sometimes tumour mutational burden determine whether immunotherapy is likely to help. Prescribing it without this evidence exposes patients to cost and side effects for little expected benefit.
Side effects that need prompt reporting
- Persistent diarrhoea — possible immune colitis
- New breathlessness or dry cough — possible lung inflammation
- Skin rash, or marked fatigue with weight change — thyroid or adrenal effects
- Yellowing of eyes, or abnormal liver tests
Frequently asked questions
Is immunotherapy a cure for cancer?
It is not a cure for cancer in general. In a subset of patients it produces long-lasting disease control, while in others it does not work at all. Honest expectations are part of the treatment discussion.
How long does immunotherapy continue?
Often up to two years if it is working and well tolerated, though this varies by cancer type and clinical situation.
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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.