To start with, we will investigate the claim that hot flashes can cure cancer. I just heard someone say this the other day, so there is no media or peer-reviewed source to condemn. However hearing it from a non-scientist in a completely non-scientific context leads me to believe it might be something that is popularly accepted, and therefore merits a good close look.
Here is the exact quote I heard:
"The temperature reached during hot flashes in menopause is exactly the temperature at which cancer cells cannot survive."There are some obvious problems with this specific claim. If this is true as stated, then no one would have cancer cells remaining in their body after undergoing a hot flash and heating up the body would be the undisputed cure for cancer.
So lets take a look at a related, but somewhat less drastic claim:
"A new study shows that having symptoms such as hot flashes during menopause appears to be tied to a lower risk of the most common kinds of breast cancer."This claim is based on an actual paper. The paper suggests that this connection is due to differing estrogen level in women with and without symptoms
"Prior studies indicate that women with menopausal symptoms have lower estrogen levels because they go through menopause as compared with women who do not experience them. Given the central role of hormones in the etiology of breast cancer, a link between menopausal symptoms and breast cancer is plausible. However, no prior studies have evaluated the association between menopausal symptoms and breast cancer risk....This is the first study to report that women who ever experienced menopausal symptoms have a substantially reduced risk of breast cancer, and that severity of hot flushes is also inversely associated with risk." (from the abstract Huang et al., 2011)The more severe the hot flashes the lower the risk of breast cancer is an exciting and useful finding, but the paper makes no claim that this is because of the heat. It certainly doesn't make any claims about other forms of cancer, or the viability of already present cancer cells during a hot flash.
Finally, this is a classic example of correlation vs. causality. The finding that the women with severe hot flashes have a lower risk of breast cancer does not mean that the hot flashes prevent breast cancer. (Hot flashes might cause the reduction in risk, but the research hasn't shown that yet) In fact, it seems equally, if not more likely that one mechanism causes both severe hot flashes and a reduced risk of breast cancer.
Huang Y, Malone KE, Cushing-Haugen KL, Daling JR, & Li CI (2011). Relationship between menopausal symptoms and risk of postmenopausal breast cancer. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology, 20 (2), 379-88 PMID: 21212063