Megace (megestrol acetate) is a drug with two separate uses for breast cancer patients. It is both a hormonal treatment for advanced breast cancer and an appetite stimulant for cancer patients who are losing weight. It comes in tablet form and is taken orally.
You may remember from your pathology report that your tumor was checked for hormone receptors. The ER status indicates whether the tumor has estrogen receptors, and the PR status shows whether it has progesterone receptors. Megace is a synthetic form of progesterone.
If breast cancer recurs, there are two main ways to go with treatment--chemotherapy or hormone therapy. If the tumor is ER and/or PR positive, then hormone therapy is a good option. It will probably have fewer side effects than chemo, and it can be just as effective.
Megace is not usually the first choice for hormone therapy. Doctors often start with an antiestrogen treatment like tamoxifen or raloxifene (Evista). In postmenopausal women an aromatase inhibitor like anastrozole (Arimidex), letrozol (Femara), or exemestane (Aromasin) may be tried. Typically these drugs will stop or slow the tumor's growth for a while and then become ineffective.
That's where Megace comes in. After the other drugs stop working, your doctor may suggest Megace. According to Dr. Susan Love's Breast Book 5th edition, Megace will work for about 20-30 percent of the women who try it. Keep in mind that the tumor must be hormone receptor positive for Megace to be effective.
Also keep in mind that sometimes a tumor's hormone receptor status will change over time, so you might ask for new tests if you have recurrent breast cancer and other treatments are not working.
One side effect of Megace is increased appetite. For a woman who is normal weight or heavy, this side effect can be annoying, but for a person who is losing appetite and weight, doctors can turn this negative side effect into a positive. The medical word for loss of appetite is cachexia. Dr. KM Fox and other researchers in a 2009 study found that up to 15% of advanced cancer patients have lost weight because of cachexia.
Loss of appetite reduces a patient's enjoyment of life, so even though there is no data to show that Megace prolongs life when it is used to increase appetite, patients and their families feel better when the patient cancer eats and maintains weight.
Megace has also been used for elderly people with weight loss, HIV patients, and people with other diseases that cause weight loss and loss of appetite.
Although Megace will not cure cancer, for those with a recurrence the extra time it can buy with relatively few side effects makes it an important tool in treating Stage IV patients. Its value in improving the quality of life for those with advanced cancer or other diseases is also important. If you or someone you are caring for has already tried other hormonal treatments or has been adversely affected by loss of appetite, ask the doctor whether Megace might be appropriate.