It varies by cancer type and stage rather than by a single rule. Practitioners report postpone periods measured in a small number of years for early-stage disease and considerably longer for later-stage or aggressive types.
There is no industry-wide waiting period, and any single number you find online is describing one carrier at one point in time.
What the waiting period is measuring
Recurrence risk, which differs enormously between cancers. That is why a uniform rule cannot exist: an early-stage thyroid cancer and a stage III colon cancer have different recurrence curves, and carriers price the curve rather than the word “remission”.
The general shape practitioners report is a shorter postpone for early-stage, well-differentiated disease, longer for node-positive or high-grade disease, and the better rate classes reserved for applicants well clear of treatment.
“In remission” is not one thing
The clinical definition varies by cancer type, and a carrier will look at what the oncology notes actually say rather than at the word itself. No evidence of disease on recent surveillance imaging is what carries weight.
What improves the file while you wait
Clean surveillance scans, accumulating. Regular oncology follow-up, documented. If cover is needed during the window, guaranteed issue bridges it without health questions, and holding it does not prevent a proper application later.
The full treatment of this topic is on Cancer history.