Making Sense of Cancer Screening Updates
TUESDAY, Dec. 20 -- As experts alter course on guidelines for cancer screenings such as mammograms and the prostate-specific antigen test, the general public is understandably confused.
Women at age 40 wonder if they should have a mammogram to look for breast cancer or wait until 50, as one U.S. organization suggests. Men of an age when prostate cancer develops may be told to forgo the prostate-specific antigen (PSA) test, contrary to standard past practice. And sexually active women may not feel safe from cervical cancer if they wait years between Pap tests.
"It's difficult to accept that having less testing is either as good or even better than having more," said Dr. Robert Mayer, faculty vice president for academic affairs at the Dana-Farber Cancer Institute in Boston.
Based on new research, some major cancer groups are advising the medical profession to be more judicious about who gets tested and when.
"I don't think the data are as conclusive that screening is as bad or as good as we had hoped," said Dr. David Penson, professor of urologic surgery and director of surgical quality and outcomes research at Vanderbilt University in Nashville.
Probably the most controversial recommendation came from the U.S. Preventive Services Task Force (USPSTF), a government body that publishes screening guidelines. It set off a furor two years ago when it announced that mammograms may not benefit women in their 40s, while women aged 50 to 74 could safely undergo screening once every two years instead of annually.
This year, the Canadian Task Force on Preventive Health Care came out with similar recommendations on breast cancer screening, suggesting that women aged 40 to 49 at average risk for breast cancer not get routine mammograms.
This, of course, runs counter to long-standing conventional wisdom that all women over the age of 40 should undergo a yearly mammogram.
These organizations reasoned that mammograms can result in false positives and unnecessary biopsies, harm that in some instances may outweigh the benefits of this type of screening. Soaring health costs may also weigh in the decision-making.
However, the American Cancer Society and the American College of Obstetricians and Gynecologists still advocate screening starting at age 40.
"I don't see a trend of backing away from endorsement for screening among many organizations," said Robert Smith, senior director of cancer control at the American Cancer Society. "Frankly, I see it in one."
But the medical establishment is backing away from PSA screening for prostate cancer, because the test is far from perfect, resulting in many unnecessary biopsies.
Increased PSA levels can indicate cancer, but they are not a foolproof measure. PSA levels rise naturally as men age, explained Mayer. Levels can also rise if men have had two or three sexual experiences in the prior few days.
"There are an enormous number of false positives," Mayer added. "How does one then say what's good for everybody?"
And not all prostate cancers are created equal, some being highly aggressive and others very slow-growing. Invasive treatment may be more harmful than watching and waiting, some doctors say.
"We know that less than 10 percent of men with prostate cancer ever die of the disease," Mayer said. "That's very different from colon cancer, where 40 to 50 percent die from it, or breast cancer, where 30 to 40 percent die from it."
The bottom line for both breast and prostate cancers: Check with your health care provider on what is the best screening schedule for you.
Cervical cancer screening guidelines have also evolved over the years.
In October, three groups, including the American Cancer Society, jointly created guidelines calling for women to get fewer cervical cancer screenings over their lifetime.
The guidelines also call for combination Pap testing and HPV (human papillomavirus) testing in women aged 30 and older, placing stronger emphasis on HPV testing than guidelines officially released at the same time from the USPSTF.
But the issue here is less controversial. "We have more sensitive tests in our ability to detect what is a slow-growing disease," said Smith.
Visit the U.S. National Cancer Institute for more on cancer screening tests.
Posted: December 2011
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