Side effects of drugs that benefit cancer patients

Almost all drugs have side effects and is always regarded as a bad thing. But it turns out there are some side effects of drugs that actually bring good luck.
Several studies have demonstrated a positive side effect of a drug that could provide benefits. For example, U.S. investigators found the side effects of estrogen therapy to cope with menopause may help reduce the risk of breast cancer. Then the viagra medication that was originally used as a heart attack, it can be useful as an impotence drug.