Centuries ago, when cartographers made their maps of the world, they had a very peculiar way of representing unexplored areas unknown to humans. In these areas they used to draw different mythological animals and supernatural creatures to warn the sailors of the danger of those places. It is an illustrative allegory of a constant in our history: beyond the frontiers of human knowledge, superstition spreads its arms with force. In medicine when, against all odds, a person affected by cancer is cured without doctors having any explanation, there is an idea that usually makes an appearance: "It's a miracle!".
Superstitions take shape from the beliefs of people who expose themselves to the unknown. Thus, for example, "miraculous" cures are of vital importance for the Catholic Church. Multiple amazing cures in patients suffering from cancer and who had prayed to certain religious people have been key to their beatifications. This is the case, for example, of St. Ezekiel Moreno (Spanish saint protector of cancer patients), whose sanctification was motivated by alleged miraculous cures in patients affected by this disease. Outside of the official religious sphere, in a more mystical and pagan environment, not a few people who claim to have cured themselves spontaneously of cancer have used to sell or promote certain spiritual beliefs, lifestyles, diets or various treatments without any scientific evidence behind.
Physicians refer to the "miraculous" cures of cancer as "spontaneous remissions (or regressions) of cancer." The official definition, established by doctors T. Everson and W. Cole in 1956 it reads as follows: "The partial or complete disappearance of a malignant tumor in the absence of any treatment or with the presence of a therapy considered inadequate to exert a significant influence on the neoplastic disease".
Attributing the spontaneous remission of a cancer to a miracle would be the equivalent of seeing lights in the sky and thinking of flying saucers (which are no longer seen, by the way, in a world full of camera phones). That we do not know the reason a priori, is not a justification to give supernatural and highly improbable explanations. Instead, following the methodological principle of the knife of Ockham, the simplest hypothesis is the one that is more likely to be correct. And the truth is that the explanation with greater possibilities of being correct is this: in rare cases, biological processes occur in the body of patients affected by cancer that cause the elimination of advanced tumors.
The above would not be any surprise. Now we know that, within all of us and at various times in our lives, cancer cells have originated. Whether these cells evolved or not to a detectable tumor depended on the defense mechanisms of our body and the aggressiveness and adaptability of tumor cells. In the absolute majority of cases, micro-cancer disappears without our having the faintest idea that such a happy event has taken place. The big difference with the "miraculous" cures of cancer is that they occur in much later stages of the disease and even after conventional medical treatments that have not been effective.
In recent years, medicine is taking more seriously the study of spontaneous cancer remissions. It is not just out of curiosity: it is likely that from your study we may know novel strategies to treat cancer.
The estimated frequency of spontaneous cancer cures is one case for every 60,000 or 100,000 patients with cancer, but it is true that we do not know with certainty for multiple reasons. Although there are more than 1,000 cases of spontaneous cancer remissions in patients described in the medical literature, it is estimated that they are a tiny part of the total. Doctors usually do not investigate in detail or publish these cases or patients stop going to doctors when healing occurs. In addition, given that, fortunately, almost all cancer patients receive medical treatment, it is very difficult to know if the reason for the cure of the cancer has been other than this treatment.
However, we do know that "miraculous" cures are not so rare. In fact, there are documented cases of spontaneous remissions for almost any type of cancer (breast, kidney, liver, lung …). In addition, for certain types of cancer, more unexplained cures are observed (such as melanoma) than for others. Thus, for example, neuroblastoma (an aggressive cancer of nervous tissue in adults) disappears spontaneously in most cases when it occurs in young children. Partial remissions are much more frequent and it is estimated that it occurs between 2 and 4 cases per 1,000. They are not miracles, they are biological phenomena that escape our knowledge due to lack of data.
It is known that the immune system is a key factor in fighting cancer cells. In fact, when a tumor reaches a certain size it is usually because the cancer cells have managed to overcome the attacks of this system. In the spontaneous remissions of advanced cancer, it could happen that there is some random stimulation of the immune system that will lead him to attack the cancer with a new strategy, producing its elimination. These stimuli could be surgeries, infections, fever, transfusions … However, in the absolute majority of patients with cancer receiving these stimuli spontaneous healing does not occur, so there is something that escapes us.
Precisely, one of the most potent advances in the medical treatment against cancer in recent years has been the development of various immunotherapies. It's about lending a hand to the immune system to attack tumor cells more effectively. If we could know what happens in those cases that heal spontaneously and by chance, we would probably have more clues to develop new immunotherapies.
Another hypothesis that would explain the spontaneous remissions of cancer is based on processes of apoptosis (programmed cell suicide) of the cancer cells that take place at random. Another explanation is based on changes in the blood supply of the tumor. If for any reason, the blood vessels surrounding the tumor disappear or decrease, the tumor may end up "suffocated" due to lack of oxygen and nutrients and thus disappears. It could also have to do with the random appearance of spontaneous mutations in the DNA of the tumor cells that favored their elimination, instead of their aggressiveness or survival.
They said in the movie Minority report that "science has robbed us of many miracles". It would not be bad for medical science to steal another miracle, explaining what happens when a patient is cured of cancer against all odds. There would be less room for magic and more for the knowledge and advancement of medicine.