Prostate tests raise dif­fi­cult ques­tions

Times Colonist - - Comment -

The predica­ment of a Vic­to­ria res­i­dent who was di­ag­nosed with Stage 3 prostate can­cer af­ter be­ing de­nied a blood test has gen­er­ated both sym­pa­thy and con­tro­versy. Grant McKen­zie was re­fused a prostate spe­cific anti­gen test at age 53. Two years later, his can­cer was found.

McKen­zie be­lieves that had he been granted the test, his can­cer would have been di­ag­nosed at an ear­lier stage. The pro­vin­cial health min­istry funds PSA tests only when or­dered by a clin­i­cian, and not for men with no symp­toms.

This is a hotly con­tested is­sue. Some ex­perts are con­vinced that PSA tests are ben­e­fi­cial be­cause they find some early-stage can­cers that might oth­er­wise have gone un­no­ticed.

On the other side of the de­bate, the Cana­dian Task Force on Pre­ven­tive Health Care has rec­om­mended do­ing away with PSA screen­ing al­to­gether (mean­ing tests of men in good health), be­cause it does more harm than good.

How can th­ese op­pos­ing views be ex­plained? It comes down to a value judg­ment. Is it bet­ter to help the few, even if it means harm­ing the many?

The task force ar­gued that PSA tests are known to pro­duce large numbers of false pos­i­tives. An Amer­i­can study found that 75 per cent of pa­tients who had high PSA scores were can­cer-free.

But that’s a prob­lem, be­cause some­one with an el­e­vated score will likely un­dergo a bat­tery of fol­lowup pro­ce­dures. Th­ese might in­clude dig­i­tal rec­tal ex­ams, ul­tra­sound imag­ing and a nee­dle biopsy. Un­avoid­ably, this con­sumes scarce re­sources and causes — in most cases — need­less anx­i­ety.

There is also the con­cern that surgery to re­move a prostate tu­mour might not be as ben­e­fi­cial as once be­lieved. With­out ques­tion, an op­er­a­tion can be life­sav­ing for pa­tients with an ag­gres­sive form of the dis­ease.

Yet a U.S. study fol­lowed 731 prostate can­cer pa­tients for 20 years. By the end of that pe­riod, the mor­tal­ity rate among those who had surgery was just four per cent lower than for those who did not. And there was a price to be paid for that rel­a­tively mod­est gain.

While es­ti­mates vary, up to 40 per cent of men who have this op­er­a­tion sub­se­quently ex­pe­ri­ence in­con­ti­nence, and as many as 75 per cent suf­fer im­po­tence.

Although in some cases th­ese side-ef­fects are tem­po­rary, in oth­ers they are not. Is it worth risk­ing such lifeal­ter­ing in­juries when the ben­e­fits of surgery are lim­ited?

A fur­ther com­pli­cat­ing fac­tor when de­cid­ing whether to screen is the fact that the ma­jor­ity of prostate tu­mours are slow-mov­ing. About 50 per cent of men age 70 have prostate can­cer cells in their body, but most die with­out ever know­ing they had the dis­ease.

That’s why many pa­tients who are di­ag­nosed in the early stages are ad­vised to post­pone treat­ment, and in­stead con­duct what’s called “watch­ful wait­ing.” That means hav­ing check­ups ev­ery six months. But this im­poses a sig­nif­i­cant psy­cho­log­i­cal strain, even if the tu­mour doesn’t progress.

There is, of course, an­other side to this. While the fiveyear sur­vival rate for prostate can­cer av­er­ages 95 per cent, more than 4,000 men die of this dis­ease each year in Canada. As the third lead­ing cause of can­cer mor­tal­ity in males, it de­mands our full at­ten­tion.

For men with­out symp­toms, per­haps the de­ci­sion comes down to a mat­ter of per­sonal choice.

One pa­tient’s qual­ity of life might be harmed sig­nif­i­cantly by years of watch­ful wait­ing. Bet­ter to leave things alone, and ac­cept what­ever risk that en­tails.

An­other would gladly put up with any in­con­ve­nience to buy a de­gree of cer­tainty.

Given the con­flict­ing opin­ions among ex­perts, prob­a­bly the best ad­vice is that men over 50 should dis­cuss their op­tions fully with a GP.

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