The mammogram is not reliable for women younger than 40 because their breast tissue is too dense and false negatives may result. A recent drug used to fight breast cancer is Tamoxifen. It blocks the action of estrogen on the breast's estrogen receptor, and is useful in early stages. Often in late stages, the cancer takes a new form where it loses estrogen receptors and Tamoxifen becomes ineffective. Thereafter, traditional chemo- and radiation therapy are used.
Men experience an age-related decrease in testicular size and in sperm production.
In some men, there is an almost linear decline in testosterone production that becomes noticeable after the age of 40. However, many males experience no decline in testosterone levels. Both the decrease in testosterone and the decrease in sperm production causes an age-related decrease in fertility. The loss of testosterone also results in a decrease in bone and muscle mass in the aging male. The loss of testosterone may also contribute to sexual dysfunction with age in men.