MIRACLE, n. An act or event out of the order of nature and unaccountable, as beating a normal hand of four kings and an ace with four aces and a king.
Ambrose Bierce, The Devil's Dictionary

All sorts of things are attributed to treatment which have nothing whatever to do with it. Many people have had the experience of having been given an antibiotic for some disease and having the disease disappear in about three or four days. They attribute the "cure" to those antibiotics, although there is no antibiotic that I know of that does not exert some effect in the first forty-eight hours if it is going to work at all. The first clue to the working of this mysterious cure mechanism came when my wife was about to be delivered of her first child. The baby did not come quite as quickly as expected, and my wife was getting a bit anxious. The doctor prescribed some castor oil and said that, if she did not go into labor by the following morning, to take the castor oil. She went into labor at 5 A.M. and the obstetrician pointed out that, had she taken the castor oil the previous evening, the delivery would have been attributed to the treatment.
The second case in point is the case of my son's warts. He had been bothered with them for some time, and my wife consulted our pediatrician about their treatment. He gave her a prescription for some medicine which he assured her would work. The prescription worked wonders, but we never filled it. It was a week or two before she was ready to have it filled at the one and only pharmacy that made this remedy up; but by that time the warts had all disappeared. I am now going to discuss the spontaneous cure of cancer. Spontaneous is a very fancy word which means something that happens for which we have no explanation. But if this "cure" happens after someone has tried some worthless treatment, the patient figures that the doctor, or whoever it was, had cured him.
Occasionally some people recover from "incurable" cancer without surgical or medical intervention. This is part of the basis of the reputation of many quack cancer healers, shrines, and the power of prayer. Most of these people never had cancer at all. They either think they had cancer, or have been diagnosed as having cancer by people who were incompetent or mistaken. Of the remainder, a few represent questionable diagnosis.
There are, however, rare cases where people have been diagnosed as having cancer by the unanimous opinion of expert pathologists and have still recovered. There is no way of explaining this. It is a fact. How can this occur? Perhaps part of the answer may be found in the experimental fact that we sometimes cannot distinguish changes in cell populations which are a function of a genetic change in the cell itself, from changes which occur as a result of some change in the whole animal. If a pellet of estrogen (female sex hormone) is implanted in certain strains of guinea pigs, they develop what looks like metastatic fibrosarcomas (a rapidly spreading cancer of the connective tissue). If the pellet is removed, the tumors disappear. In some strains of rats, a similar pellet of a synthetic female sex hormone (stilbestrol) will induce the appearance of "breast cancer. " When the pellet is removed, these tumors disappear. A similar phenomenon might occur very rarely in human beings. We do not know what causes these miraculous cures; we can only guess. Guesses based on very little knowledge are highly unreliable.
It is a fairly common occurence for patients to undergo what is called remission. Remission means that the symptoms, and sometimes the tumor, disappear for a period of time. This disappearance of symptoms or tumor may be of a relatively long duration (in Hodgkin's disease it can be as long as ten years) or can be relatively short. Usually remissions occur following some form of treatment, and sometimes they occur without medical intervention. In the hands of the inexperienced, a remission is sometimes taken as a cure; which it is not. In evaluating experimental treatment, the only way to tell a remission from a cure is to wait for a long enough time and see if the tumor reoccurs. If a remission follows some treatment (worthless or not), the treatment is usually considered to be successful.
Another thing worth remembering is what I have been talking about as "competing risks" in the chapter on Chemical Carcinogenesis. If a person is treated for breast cancer and dies of a heart attack two years later, the breast cancer can be considered as "cured."