Diminution or abatement of a disease over time, without formal treatment
Spontaneous remission, also called spontaneous healingorspontaneous regression, is an unexpected improvement or cure from a disease that usually progresses. These terms are commonly used for unexpected transient or final improvements in cancer. Spontaneous remissions concern cancers of the haematopoietic system (blood cancer, e.g., leukemia), while spontaneous regressions concern palpable tumors; however, both terms are often used interchangeably.
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."[1]
It has long been assumed that spontaneous regressions, let alone cures, from cancer are rare phenomena, and that some forms of cancer are more prone to unexpected courses (melanoma, neuroblastoma, lymphoma) than others (carcinoma). Frequency was estimated to be about 1 in 100,000 cancers;[2] however, this proportion might be an under- or an overestimate. For one, not all cases of spontaneous regression can be apprehended, either because the case was not well documented or the physician was not willing to publish, or simply because the patient ceased to attend a clinic any more. On the other hand, for the past 100 years almost all cancer patients have received some form of treatment, and the influence of that treatment cannot always be excluded.
It is likely that the frequency of spontaneous regression in small tumors has been drastically underrated. In a carefully designed study on mammography it was found that 22% of all breast cancer cases underwent spontaneous regression.[3]
Everson and Cole offered as explanation for spontaneous regression from cancer:
In many of the collected cases[...] it must be acknowledged that the factors or mechanisms responsible for spontaneous regression are obscure or unknown in the light of present knowledge. However, in some of the cases, available knowledge permits one to infer that hormonal influences probably were important.[...] In other cases, the protocols strongly suggest that an immune mechanism was responsible.[1]
Challis and Stam, even more at a loss, concluded in 1989, "In summary, we are left to conclude that, although a great number of interesting and unusual cases continue to be published annually, there is still little conclusive data that explains the occurrence of spontaneous regression."[4]
Apoptosis (programmed cell death) and angiogenesis (growth of new blood vessels) are sometimes discussed as possible causes of spontaneous regression. But both mechanisms need appropriate biochemical triggers and cannot initiate on their own. Indeed, in many cancer cells apoptosis is defective, and angiogenesis is activated, both of these effects being caused by mutations in cancer cells; cancer exists because both mechanisms are malfunctioning.[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. This could be confirmed by collecting epidemiological studies.[7][8]
^Zahl, P. H.; Maehlen, J.; Welch, H. G. (2008). "The natural history of invasive breast cancers detected by screening mammography". Archives of Internal Medicine. 168 (21): 2311–6. doi:10.1001/archinte.168.21.2311. PMID19029493.
^Hobohm, U.; Stanford, J. L.; Grange, J. M. (2008). "Pathogen-associated molecular pattern in cancer immunotherapy". Critical Reviews in Immunology. 28 (2): 95–107. doi:10.1615/critrevimmunol.v28.i2.10. PMID18540826.
^Rohdenburg, G. L. (1 April 1918). "Fluctuations in the Growth Energy of Malignant Tumors in Man, with Especial Reference to Spontaneous Recession". The Journal of Cancer Research. 3 (2): 193–225. doi:10.1158/jcr.1918.193 (inactive 31 January 2024).{{cite journal}}: CS1 maint: DOI inactive as of January 2024 (link)
^Fauvet, J.; Roujeau, J.; Piet, R. (1964). "Spontaneous Cancer Cures and Regressions". La Revue du Praticien. 14: 2177–80. PMID14157391.
^Boyd W: The spontaneous regression of cancer. Charles Thomas, Publ., Springfield Ill. 1966 (Book)
^Cole, W. H. (1976). "Spontaneous regression of cancer and the importance of finding its cause". National Cancer Institute Monograph. 44: 5–9. PMID799760.
^O'Regan, Brendan; Hirschberg, Carlyle (1993). Spontaneous Remission. An Annotated Bibliography. Sausalito, California: Institute of Noetic Sciences. ISBN978-0-943951-17-1.
