William Aiken

In part one, we looked at the treatment of early prostate cancer. In this article we will examine the treatment of locally-advanced and disseminated prostate cancer.

Before looking at the specific treatment options, it is important to understand that prostate cancer is a hormone - sensitive cancer. The prostate requires the presence of adequate blood levels of the male hormone, testosterone, to grow and mature. Prostate cancer too, requires testosterone to grow and spread. Testosterone is primarily produced by the testicles and to a lesser extent by the adrenal glands. Remove the influence of testosterone from prostate cancer cells and the cancer will shrink no matter where in the body it has spread to, in the vast majority of cases.

This was first determined by Huggins who was later awarded the Nobel Prize in medicine for this discovery. This knowledge is utilised in treating advanced and disseminated prostate cancer.

Cut testosterone levels

There are a number of ways in which the testosterone blood level can be reduced. Oral medication may be taken in the form of female hormones (oestrogenic compounds) which causes the pituitary gland to switch off its production of hormones which drive the production of testosterone by the testicles.

Other oral medications which belong to the steroid class can also be used to achieve this same effect, example cyproterone acetate (Androcur). Another class of drugs given by monthly or three monthly injections initially stimulates the pituitary to produce the hormones, increasing testosterone production but with perpetual exposure to this drug called an LHRH analogue, the pituitary down - regulates or simply turns down its secretion of hormones thereby decreasing testosterone production.

This class of drugs includes goserlin acetate (Zoladex ), leuprolide (Lucrin ) and Lectrum . Another class of oral drugs is co-administered with the LHRH analogues when therapy is initiated to offset the effects of the initial rise in testosterone levels. The oral and injectable medications mentioned, cause reversible decreases in testosterone production; the testosterone level eventually returns to normal after the drug is discontinued. These methods are said to bring about a state of medical castration.

Remove testicles

The testosterone level can, of course, be permanently decreased by removing both testicles - a surgical castration. Surgical castration is the oldest (and the cheapest) method of hormonally manipulating advanced prostate cancer to cause shrinkage, but it is also the most psychologically traumatic and it involves surgery, minor though it may be.

All these methods of causing a low testosterone level are equally effective, but they vary in their costs and side - effect profiles. For example, 80 per cent of men on oestrogenic compounds have some noticeable breast enlargement, sometimes dramatically so. Other side effects include fluid retention and an increased tendency for blood clots forming spontaneously. A particularly distressing side effect of castration and some drugs is hot flashes which are equivalent to those women regularly experience when going through menopause. Decreased muscle and bone density as well as weight gain are possible side effects. All men experience decreased sexual desire and a majority will have erectile dysfunction.

The response of the cancer to medication or surgery is monitored by noting the patients' symptoms as well as the prostate specific antigen level which is expected to dramatically fall in most cases.

When the cancer has spread beyond the confines of the prostate gland to involve the tissues immediately surrounding it, without involving the draining lymph glands, it is called locally advanced. Locally-advanced prostate cancer is generally treated by a combination of external beam radiation and hormone therapy. This combination has been shown to be better than radiation alone in terms of recurrence-free survival. Radiation is administered daily over a six-week period while hormone therapy is taken for three years.

Disseminated prostate cancer is generally treated by hormone therapy alone, utilising any of the methods discussed above.

Dr. William Aiken is the head of urology at the University Hospital of the West Indies and president of the Jamaica Urological Society; email: yourhealth@gleanerjm.com.