Cancer: what your policy covers — and the small print that decides it
Cancer drives more critical illness claims than anything else. It also carries the longest list of exclusions.
Key facts at a glance
- Typical definition style
- Invasive malignant tumour, positively diagnosed with histological confirmation
- Common exclusions
- Pre-malignant, non-invasive and in-situ tumours; low malignant potential
- The prostate threshold
- Prostate tumours commonly need a Gleason score of 7+ or specified progression
- Where quality differs most
- Early-stage and low-grade cancers covered by additional payments
Reviewed by the LifeInsuranceForMe advice team · Last updated August 2026 · Definitions vary between policies — your own wording is decisive
The headline definition
Most policies define cancer as a malignant tumour, positively diagnosed with histological confirmation, with uncontrolled growth of malignant cells and invasion of tissue. Leukaemia, sarcoma and lymphoma are typically included. Diagnosed invasive cancer of this kind is generally covered in full.
The exclusions that surprise people
The standard carve-outs are cancers histologically classified as pre-malignant, non-invasive, in-situ, of borderline malignancy or of low malignant potential. Prostate cancer commonly needs a Gleason score of 7 or above, or progression to a specified clinical staging, before a full payment is due. Most non-melanoma skin cancers are excluded unless they have spread. Melanoma generally must have invaded beyond the outer layer of skin.
Where good policies pull ahead
The better modern policies pay additional, capped amounts for specified early-stage cancers. Examples: low-grade prostate cancer that is actually being treated, or carcinoma in situ of specified sites treated by surgery. These payments don't usually reduce your main cover. Older policies rarely include them. It is one of the clearest quality gaps between policy generations.
Why this matters more than price
Early-stage diagnoses are common. Whether one pays £0 or a five-figure additional payment depends entirely on wording that never appears in a price table.
- Which early-stage or low-grade cancers does this policy pay anything for?
- What exactly does the prostate cancer wording require — score and staging?
- If I claim an additional payment, does it reduce my main sum assured?
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