6 Things You Need To Know About Health Screen­ing Tests

Wellness Update - - Front Page - By Michael Rabovsky, MD

Re­cently, dur­ing her an­nual “well woman” exam, Mary, a healthy 50-year-old school­teacher, asked me about screen­ing her for ovar­ian can­cer.

Trag­i­cally, one of Mary’s friends re­cently died from ovar­ian can­cer. Mary has no risk fac­tors for ovar­ian can­cer and no fam­ily history of ovar­ian or other can­cers. I ex­plained to Mary that, un­for­tu­nately, there are no re­li­able screen­ing tools to di­ag­nose ovar­ian can­cer.

We went on to have a dis­cus­sion about screen­ing and the char­ac­ter­is­tics of re­li­able med­i­cal screen­ing tests. The pur­pose of screen­ing is to iden­tify an un­rec­og­nized dis­ease or con­di­tion in peo­ple who feel well and have no symp­toms.

6 WAYS TO EVAL­U­ATE A SCREEN­ING TEST

Screen­ing tests should be ap­plied to those con­di­tions that meet the fol­low­ing cri­te­ria:

1 Con­sider the treat­ment op­tions. Ac­cept­able meth­ods of treat­ment must be avail­able.

2 Look at the im­pact of the ill­ness. The dis­ease or con­di­tion must have a sig­nif­i­cant ef­fect on the qual­ity of life and life ex­pectancy.

3 De­ter­mine whether treat­ing asymp­to­matic dis­ease will help. The dis­ease must have a pe­riod dur­ing which there are no symp­toms, when de­tec­tion and treat­ment will sig­nif­i­cantly re­duce ill­ness and/or death. Fur­ther­more, treat­ment in this asymp­to­matic phase must yield a ther­a­peu­tic re­sult su­pe­rior to that ob­tained by de­lay­ing treat­ment un­til symp­toms ap­pear.

4 The dis­ease in­ci­dence must be high. The in­ci­dence, or the num­ber of new cases iden­ti­fied, must be sig­nif­i­cant to jus­tify the cost of screen­ing to a pop­u­la­tion of peo­ple.

5 Screen­ing must be easy to do. The screen­ing tests must be sim­ple to per­form, sim­ple to in­ter­pret and rel­a­tively com­fort­able to peo­ple.

6 The costs must be rea­son­able. The tests must be avail­able at a rea­son­able cost. This not only ap­plies to the mon­e­tary cost of per­form­ing the tests, but also to the eval­u­a­tion of false pos­i­tive tests, the psy­cho­log­i­cal im­pact on a per­son of a false­pos­i­tive test, and con­sid­er­a­tion of the med­i­cal risk in­curred in per­form­ing the test as well as fur­ther test­ing re­quired in the workup of a pos­i­tive test.

OVAR­IAN CAN­CER SCREEN­ING: WHY YOU MAY NOT NEED IT

Ovar­ian can­cer is the lead­ing cause of gyne­co­logic can­cer deaths in the United States. Ap­prox­i­mately 22,000 U.S. cases of ovar­ian can­cer are di­ag­nosed an­nu­ally, with 14,000 deaths each year.

If di­ag­nosed in an ear­lier stage, the five-year sur­vival rate (the per­cent­age of peo­ple alive five years af­ter di­ag­no­sis) can be as high as 90 per­cent. The five-year sur­vival rate drops to 25 per­cent if the di­ag­no­sis is made at a later stage.

The goal of screen­ing would, there­fore, be to di­ag­nose ovar­ian can­cer in its ear­lier stages, when treat­ment would have a ben­e­fi­cial ef­fect on out­comes. Sev­eral tests have been used to screen for ovar­ian can­cer. But three large stud­ies failed to show that screen­ing re­sulted in ear­lier di­ag­no­sis of ovar­ian can­cer.

So, although there is ev­i­dence to show that di­ag­nos­ing ovar­ian can­cer at its ear­lier asymp­to­matic stages leads to bet­ter sur­vival, there have been no tests shown to de­tect ovar­ian can­cer in these ear­lier stages.

Fur­ther­more, pos­i­tive tests for ovar­ian can­cer gen­er­ally lead to sur­gi­cal pro­ce­dures. One study re­vealed that 15 per­cent of women un­der­go­ing a sur­gi­cal pro­ce­dure for a false-pos­i­tive screen ex­pe­ri­enced a se­ri­ous com­pli­ca­tion re­lated to the surgery.

So I ex­plained to Mary that not only was there no ev­i­dence that screen­ing led to bet­ter out­comes, but that with the tests cur­rently avail­able to di­ag­nose ovar­ian can­cer, screen­ing could lead to sig­nif­i­cantly more po­ten­tial harm than good.

COL­OREC­TAL CAN­CER SCREEN­ING: WHY YOU NEED IT

In con­trast, col­orec­tal can­cer is a con­di­tion that meets the afore­men­tioned screen­ing cri­te­ria.

Most col­orec­tal can­cers de­velop slowly over sev­eral years; be­fore a can­cer de­vel­ops, a growth of tis­sue or tu­mor usu­ally be­gins as a non-can­cer­ous polyp on the in­ner lin­ing of the colon or rec­tum.

A polyp is a be­nign, non-can­cer­ous tu­mor. Some polyps can progress into a can­cer but not all do. There are gen­er­ally no symp­toms as­so­ci­ated with polyps. When a pre­can­cer­ous polyp is iden­ti­fied by a screen­ing test, pro­gres­sion to can­cer is pre­vented, and there is no ef­fect on health or life ex­pectancy.

How­ever, when col­orec­tal can­cer is di­ag­nosed af­ter symp­toms de­velop, the five-year sur­vival rate can range from 6 per­cent to 74 per­cent, depend­ing on the stage of the can­cer at the time of di­ag­no­sis.

Colon can­cer af­fects a sig­nif­i­cant num­ber of peo­ple, there are ac­cept­able screen­ing meth­ods and treat­ments, and iden­ti­fy­ing and treat­ing pre­can­cer­ous or early-stage can­cer in the asymp­to­matic pe­riod leads to bet­ter out­comes.

Be­cause it meets screen­ing cri­te­ria and the in­ci­dence of col­orec­tal can­cer starts to in­crease at age 50, I rec­om­mended that Mary get screened.

OTHER SCREEN­ING TESTS THAT ARE CRIT­I­CAL

In ad­di­tion to screen­ing for col­orec­tal can­cer, I also ad­vised Mary to be screened for breast can­cer with an an­nual mam­mo­gram and for cer­vi­cal can­cer with a Pap smear and HPV, or hu­man pa­pil­lo­ma­tous virus, test ev­ery five years. We re­viewed the warn­ing signs of skin can­cer as well. I also coun­seled Mary to have a blood test to check her lipid pro­file, and a fast­ing blood sugar test as a screen for di­a­betes.

The mes­sage here is that screen­ing rec­om­men­da­tions vary, and it’s im­por­tant to dis­cuss the ap­pro­pri­ate screen­ing tests with your doc­tor.

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