The spontaneous regression and remission from cancer was defined by Everson and Cole in their 1966 book as "the partial or complete disappearance of a malignant tumour in the absence of all treatment, or in the presence of therapy which is considered inadequate to exert significant influence on neoplastic disease.
In a carefully designed study on mammography it was found that 22% of all breast cancer cases underwent spontaneous regression.
"[4] Apoptosis (programmed cell death) and angiogenesis (growth of new blood vessels) are sometimes discussed as possible causes of spontaneous regression.
[5] There are several case reports of spontaneous regressions from cancer occurring after a fever brought on by infection,[2][6] suggesting a possible causal connection.
If this coincidence in time would be a causal connection, it should as well precipitate as prophylactic effect, i.e. feverish infections should lower the risk to develop cancer later.