Spontaneous remission

Spontaneous remission (also known as spontaneous improvement or spontaneous regression) is a phenomenon in which an untreated disease or condition suddenly disappears for no apparent reason. It is a regression to the mean as applied to health conditions. Along with misdiagnosis, this is one of the ways in which alternative medicine can seem to cure diseases such as cancer, and why anecdotal evidence is not reliable.

Examples for various diseases
The spontaneous remission rates for cancer depend on the type: according to studies done, basal cell carcinoma and breast cancer disappear in up to 20% of cases, while the rates for melanoma haven't been studied, but have been estimated to be around 10%-20%. Autoimmune hepatitis goes into spontaneous remission in 13%-20% of cases.

Untreated tuberculosis goes away in approximately 29% of cases. About 65%-75% of people with invasive group A streptococcal infections live.

Diabetes can also undergo spontaneous remission, though the rates are unknown.

Misdiagnosis
Misdiagnosis can interfere with recorded remission rates. Malaria misdiagnosis, for instance, is a problem in Asia and Africa. In one study, out of 414 patients going to hospitals using clinical diagnosis, 412 were prescribed anti-malarial drugs, even though 413 tested negative for malaria.

Alternative medicine promoters often claim that misdiagnosis (esp. of ADD/ADHD) is another way Big Pharma pushes its drugs on people.