Prostate cancer: Debating and detecting a rampant killer

This is the first of three articles on prostate cancer prepared by Dr. Injil Abu Bakar.

NEW YORK (JP): Every 15 minutes, a man dies of prostate cancer in the United States. Despite this alarming statistic, the disease continues to get less publicity than many other cancers, largely because there are no dramatic warning signs and the malignancy progresses so slowly.

The number of cases and deaths from prostate cancer is on the rise. In the United States, the incidence of prostate cancer rose by 50 percent between 1989 and 1993. Deaths from prostate cancer are rising more slowly -- 8.6 percent from 1993 to 1994.

As disturbing as those numbers are, many cancer specialists are not surprised. After all, malignancies of the prostate are much more common in elderly and thus can be expected to increase as the average age of the population rises. In fact, about 40 percent of men aged 80 and older who die from other causes also have signs of prostate cancer. More than three-quarters of all cases occur in men over 65.

In addition to the fact that Americans are living longer, new technologies for diagnosis have made earlier detection easier. There may also be an increase in the incidence of cancer, over and above these other factors. The reason? Some experts believe that lifestyle factors such as a high-fat diet could be responsible, although no one knows for certain.

Is prostate cancer hereditary? Why does prostate cancer cluster in families? In some cases, at least, the answer lies in the genes.

After years of intensive research, a team of scientists from the U.S. and Sweden won the race to identify a specific prostate cancer gene in November 1996. The gene, called hereditary prostate cancer (HPC1) has been located on chromosome 1, but since it has not yet been cloned, its function is not known. It is estimated that one in 500 American men may carry the gene which may be responsible for about 3 percent of all prostate cancers.

Although HPC1 is the first known prostate cancer gene, there are almost certainly others. About two-thirds of hereditary prostate cancers are not explained by HPC1 and non-generic factors may also be important. For example, some studies suggest the link may depend on testosterone levels, which could be higher in different families.

Environmental factors may also be important. Families share more than genes and hormones levels; familial prostate cancer may also be explained by environmental exposures, dietary habits or lifestyle patterns that are shared by close relatives.

Early Detection Strategies

As with many diseases, prostate cancers diagnosed early have better treatment outcomes than malignancies found at later stages. Cure rates are excellent for cancer that is discovered and treated when it is still confined to the prostate gland.

About 95 percent of men with localized prostate cancer treated by surgery are still alive after five years. But when cancer cells spread beyond the prostate -- to lymph nodes, bones, the liver, bladder or rectum -- cure rates are extremely low.

Unfortunately, early detection is difficult because most men don't exhibit any symptoms in the initial stages of the disease. Symptoms ultimately surface if the cancer goes untreated long enough, and by then the likelihood of successful therapy has decreased substantially.

It is the absence of early symptoms that makes regular prostate checkups important. Screening techniques -- the digital rectal examination (DRE) and the prostate specific antigen (PSA) test -- offer the only hope of discovering early prostate malignancies. Although these tests are not perfect, they can be lifesavers.

There is little disagreement about the DRE. The American Cancer Society and the National Cancer Institute recommend that men have this test annually beginning at age 40. Although the American Cancer Society also advises men to have routine PSA tests beginning at age 50, and for those at high risk, starting at age 40, many doctors (and the National Cancer Institute) disagree.

Much debate centers around the accuracy of the test, how the results should be interpreted and used, and early detection's impact on treatment outcomes. Many men with high PSA levels do not have cancer; conversely, some men with prostate cancer have normal PSA readings.

Doctors supporting widespread use of the test believe that the degree of PSA elevation indicates how likely cancer is to exist and that the results can serve as a guide to further evaluation.

A PSA reading of 4 nanograms (billionths of a gram) per milliliter of blood (ng/ml) is considered the cutoff point for "normal" by many physicians; anything above 4 ng/ml may call for further evaluation. If a man has a PSA between 4 and 10 ng/ml, his chance of having prostate cancer is between 20 percent and 25 percent; if his PSA is greater than 10, the likelihood increases to about 60 percent.

These indicators, however, can be misleading; some men with PSAs of 4 and a normal DRE turn out to have prostate cancer, while those with levels over 10 may not. To further complicate matters, PSA levels appear to depend partly on age -- that is, a PSA of 5 might be considered normal for a 73-year-old man, whereas a PSA of 3.9 in a 50-year-old man might be a red flag.

For that reason, some researchers advocate adjusting "normal" levels for different ages.

Although a combination of PSA testing and DRE may nearly double the detection rate for early-stage prostate cancer, there is a catch: low grade, low volume cancers may progress so slowly that they do not pose an immediate threat to many men, especially older men.

Thus, many cases of prostate cancer may be treated needlessly, say doctors who are opposed to widespread PSA screening.

They express concern that an elevated PSA level will cause patients to worry and undergo tests and procedures that entail risk. In many cases, a suspicious PSA test will lead to additional procedures (ultrasonography and biopsies) and possibly to major surgery or radiation. It is extremely important for a man to understand the uncertainties and decisions he will face before choosing to have his PSA level measured.

The writer is a general practitioner based in Denpasar, Bali, and can be contacted at injila@hotmail.com.