Cancer Screenings: More Not Always Better
Women across the USA have been shocked and angered by new advice to get fewer mammograms. Yet experts have been debating the risks of mammograms and other cancer screenings for more than a decade.
There's growing evidence that cancer screenings aren't always helpful - and can sometimes be harmful, say Lisa Schwartz and Steve Woloshin of the Veterans Affairs Outcomes Group in White River Junction, Vt.
A number of medical groups also have scaled back their cancer screening guidelines:
The U.S. Preventive Services Task Force, an independent panel of government-appointed experts, two weeks ago advised most women ages 40 to 49 not to get "routine" mammograms because of concerns that the tests cause too many false alarms and even unnecessary treatment. While the panel advised that women 50 to 74 should get mammograms every other year, it said younger women should make up their own minds. In 2007, the American College of Physicians made similar recommendations for women in their 40s.
A few days after the task force's announcement, the American College of Obstetricians and Gynecologists revised its guidelines for cervical cancer screening.
The group recommended that women wait until age 21 for their first Pap smear and get follow-up exams every two to three years, depending on their age and medical history.
Last year, the task force said men over age 75 shouldn't be screened for prostate cancer, noting that men this age are more likely to die of something else before a prostate tumor could harm them. In March, two long-running and highly anticipated studies found that prostate cancer screening saves few, if any, lives but may hurt countless men by leading them to undergo therapies that can cause impotence, incontinence and even death.
Experts say they've revised their recommendations over the years as they've learned more about cancer - and the unintended side effects of treatment.
For instance, doctors treat cervical precancers much less aggressively today than they did 20 or 30 years ago, partly because they now know that many of these lesions go away by themselves, without treatment, says Alan Waxman of the University of New Mexico in Albuquerque, who helped develop the new guidelines. Though doctors shouldn't ignore cervical lesions, it's often safe to monitor them rather than remove them surgically.
In fact, treating the lesions can scar the cervix and impair a woman's future fertility. Studies show that women who have cervical lesions removed are more likely than others to give birth prematurely, Waxman says.
Waxman says there's overwhelming evidence, however, that Pap smears - when targeted to the right age groups - have a positive effect. Thanks to Pap smears, cervical cancer rates have plunged by more than 50% in the past 30 years. Screening women by age 21 gives doctors plenty of time to detect and treat cervical cancers, which typically don't develop until a woman is in her 40s.
Doctors are concerned about mammograms for different reasons. That's because mammograms and other screenings sometimes find cancers that are relatively harmless, with no potential to spread around the body and threaten a woman's life, Schwartz and Woloshin say.
According to the American Cancer Society's Otis Brawley, population-based studies suggest that 10% to 33% of early breast cancers may not actually need to be treated. Because doctors can't tell which early breast tumors will eventually turn deadly, they typically treat all of them, he says. Early tumors - those confined to the breast - are usually treated with surgery and may also require radiation and years of drug therapy, as well.
In spite of those risks, Brawley strongly believes mammograms are still worthwhile.
About 12,000 lives could be saved in the next decade if every woman in her 40s got regular mammograms, either annually or every other year, Brawley says. Providing regular mammograms to all women in their 50s and 60s, including the 30% who never get them, would save an additional 20,000 lives over the next decade.
"It's an imperfect test, but it's the best test we have," Brawley says. "There is evidence it saves lives, and therefore we should use it. Women deserve a better test, and we need to work hard and fund research to find a better test."
Explaining such complex information isn't easy, says Fran Visco, president of the National Breast Cancer Coalition.
"We need to take time to help people understand screening," she says. "More health care is not always better health care."
For many women, however, breast cancer is an emotional issue, not a scientific question.
After two or three decades of breast cancer awareness campaigns, most women have heard - and taken to heart - sound bites such as, "Early detection saves lives," Visco says. Relatively few women are familiar with mammography's limitations - partly because their doctors never mention them.
And - thanks to mammograms, which led to a large increase in the number of people diagnosed with breast cancer - many people have been touched by the disease, either directly or through relatives and friends. The growing incidence of breast cancer has made it seem even more frightening to women, who now sharply overestimate their risk, says Schwartz, of the Veterans Affairs Outcomes Group.
Women consistently say they fear breast cancer more than heart disease, even though heart problems are more likely to kill them, Schwartz says.
In a USA TODAY/Gallup Poll released last week, 40% of women surveyed estimated that a 40-year-old's chance of developing breast cancer over the next decade was 20% to 50%. The real risk is 1.4%, the National Cancer Institute says.
Many of the nation's 2 million breast cancer survivors credit the tests with their survival, Visco says.
Yet these women "can't really know if the mammogram saved their life," says Peter Bach, an epidemiologist at New York's Memorial-Sloan Cancer Center. "We don't know if the cancer would have metastasized. We don't know if you would have found it anyway six months later."