Prostate Cancer Tests


Dear Dr. B: Can you please tell me about the new test under development for early detection of prostate cancer?

Answer: I received this question from a friend whose style of writing and sense of humour I enjoy. The e-mail contained a comment on my last column on aspirin and colon cancer and the photograph accompanying the article showing a flexible sigmoidoscope. Here in part is what my friend said:

‘Imaginative photo. We amateurs still squirm about such “personal” things and, I’m sure, men more than women, are real wimps about poking around the body. Of course, to a medical person it is a smart surgical instrument used in an everyday procedure. To a patient it is perceived as a fire hose up the whazoo… Just the other day I was discussing, in a casual conversation, the old finger-vs.-PSA test… Today, through bleary eyes, I read a piece in the Globe about new research and new tests under development. I know you’ve hit this before. But it might be worth a visit to this subject again some time.’

My friend is right. It is time to revisit the subject because prostate cancer is the most frequent cancer and the second leading cause of death from cancer in men, exceeded only by lung cancer. In our region, 80 to 90 new cases of prostate cancers are diagnosed each year. And each year 10 to 15 patients die of the disease.

The walnut size prostate gland lies below the urinary bladder in front of the lowest inch of the rectum, through which it can readily be felt on digital rectal examination. The gland has an important role in the proper flow of urine. It also provides the proteins and ions that form the bulk of the semen. In conjunction with other smaller glands in the vicinity, the prostate gland produces secretions that serve to lubricate the reproductive system and provide a vehicle for storage and passage of sperms.

Once upon a time, “the old finger” i.e. digital rectal examination (DRE) was the only crude way to pick up early prostate cancer. Although DRE has a cancer detection rate of only 0.8 to 7.2 percent, it remains an important test that can be done easily in a doctor’s office. It also checks for anal and rectal tumours.

Then came the PSA blood test. PSA was expected to replace the embarrassing and uncomfortable DRE. And it was promoted as an ideal test for screening and early detection of prostate cancer. But this hope has not materialized.

Now a group of researchers from the University of Michigan Medical School are working on a test which would use the body’s own immune system to detect prostate cancer early. That makes sense as the immune system, in response to cancer, releases thousands of chemicals into the bloodstream to destroy the tumor.

The new blood test looks for 22 of these chemicals that specifically fight prostate cancer. The preliminary report indicates that these chemicals are more reliable than PSA in detecting prostate cancer. But the bad news is that it will be several years before this test is perfected and marketed for everyday use.

In the meantime, we have to rely on “the old finger” and PSA test. Findings from a new national research study released recently by the Prostate Cancer Research Foundation of Canada (PCRF) found very few Canadian men are willing to discuss prostate cancer and PSA test with their family doctors. PCRF has launched a campaign with a slogan “Don’t Get Scared. Get Tested.” More information can be found on PCRF website, www.prostatecancer.ca.

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