Hormones are chemicals secreted by the body. These chemicals are responsible for controlling physical development from puberty to old age. Some types of tumors require the presence of hormones to grow. Doctors try to kill such tumors by manipulating the body's hormone supply. This involves administering a hormone or hormone-like chemical, which counters the required hormone's effects. This technique, called hormone therapy, deprives the body of the hormone needed for tumor growth. Malignancies of the breast and prostate are especially vulnerable to this kind of treatment.
In earlier forms of the therapy, organs responsible for hormone production, ovaries in the case of women and testes in the case of men, as well as the adrenal glands were removed. This resulted in severe physical and psychological side effects including hot flashes, increased risk of heart disease, men growing breasts and facial hair in women.
Thanks to some new drugs, treatment can stem hormone supply without these unacceptable side effects. Tumor cells have proteins
that sit on the cell surface and combine chemically with hormones in the bloodstream, taking them inside and using them to grow. These proteins are called receptor sites. The new drugs compete with hormones for these sites. They are taken into the cell in preference to the hormone and kill the cancer cell from within. The most successful example of this is Tamoxifen, a drug used for breast cancer therapy, which competes with estrogen, a hormone needed by breast cancer cells for growth.
The tumour must first be tested for the presence of estrogen receptors to ascertain whether they will respond. A positive test means that the cell has estrogen receptors and that the cancer depends on hormones to grow and so is likely to shrink with hormone manipulation. The more the receptors, the better the chance of success. Tamoxifen may be used along with another hormone deprivation drug, called aminogluthethimide, which targets the adrenal glands, another hormone producing site. Steroids may be needed while therapy is going on, but once therapy is stopped; the adrenal glands will again start normal functioning.
In an analogous case, the drug Leuprolide has been used to treat prostate cancer by starving tumours of testosterone. However the effect may not last for very long. After a year or two, the body becomes immune to hormone suppression and the cancer could become resistant to the therapy. So doctors are beginning to use a drug like flutamide along with leuprolide to ensure a more complete deprivation of the male hormone. This therapy is especially useful for men who cannot have surgery.
The real value of hormone therapy is in combination with other therapies. They may be used before surgery to shrink a tumour to an operable size or after surgery to mop up or control cells that escaped the scalpel. In some cases this may be enough, but in others, chemotherapy may still be indicated to finish the job. However, less toxic doses of these drugs may then be required.
Although side effects to hormone therapy are far milder than those to chemotherapy, they should not be dismissed. Men may notice softened skin or larger breasts, while women may develop a lowered voice. Hot flashes can be relieved by daily doses of Vitamin E. Weight gain from steroids can be reversed by taking a low sodium diet and regular exercise. These side effects are all reversible.
Side effects must be closely monitored to determine how the treatment is working. If you experience bone pain, for example, it could be an indication that hormones are affecting distant sites. Reporting such side effects to the doctor is very important.