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(HealthNewsDigest.com) – SAN ANTONIO — Twenty years of screening for breast and prostate cancer – the most diagnosed cancers for women and men respectively – have not brought the anticipated decline in deaths from these diseases, argue experts from the University of California, San Francisco and The University of Texas Health Science Center at San Antonio in an opinion piece published in the Journal of the American Medical Association.
Instead, overall cancer rates are higher, many more patients are being treated, and the incidence of aggressive or later-stage disease has not been significantly decreased, the authors conclude. Current screening programs are leading to “potential tumor over-detection and over-treatment,” they write in the Oct. 21, 2009, issue of JAMA.
“People will think that we’re saying screening is bad, and nothing could be further from the truth,” said Ian Thompson, M.D., professor and chairman of the Department of Urology at the UT Health Science Center. “What we are saying is that if you want to stop suffering and death from these diseases, you can’t rely on screening alone.”
The authors said that breast cancer and prostate cancer screening has not led to a more significant drop in deaths in the U.S. for two primary reasons: Screening increases the detection of slow growing and idle tumors, and it often misses the most aggressive cancers because many may not be detected early enough for cure.
“The basic assumption that screening programs that find and treat early-stage disease will then prevent late-stage disease, or prevent cancer from spreading, may not always be correct,” added Dr. Thompson. “If a tumor is aggressive, finding it early may not prevent death.”
Dr. Thompson holds the Glenda and Gary Woods Distinguished Chair in Genitourinary Oncology at the Cancer Therapy & Research Center at the UT Health Science Center at San Antonio, and the Henry B. and Edna Smith Dielmann Memorial Chair in Urologic Science at the UT Health Science Center. He led the Prostate Cancer Prevention Trial, a study of 18,882 men from around the U.S., which demonstrated that the drug finasteride reduces a man’s risk of prostate cancer by 24.8 percent.
“Screening does provide some benefit, but the problem is that the benefit is not nearly as much as we hoped and comes at the cost of over-diagnosis and over-treatment,” said Laura Esserman, M.D., M.B.A., professor of surgery and radiology, director of the UCSF Carol Franc Buck Breast Care Center, and co-leader of the breast oncology program at the UCSF Helen Diller Family Comprehensive Cancer Center.
“We need to focus on developing new tools to identify men and women at risk for the most aggressive cancers, to identify at the time of diagnosis those who have indolent or ‘idle’ tumors that are not life-threatening,” she added. “If we can identify groups of patients that don’t need much treatment, or don’t need to be screened, wouldn’t that be great? Screening is by no means perfect. We should want to make it better. For both breast and prostate cancer, we need to invest in changing our focus from the cancers that won’t kill people to the ones that do.”
Otis Brawley, M.D., chief medical officer of the American Cancer Society, said the paper is right on target. “In the case of some screening for some cancers, modern medicine has overpromised. Some of our successes are not as significant as first thought,” said Dr. Brawley, professor of hematology, oncology and epidemiology at Emory University. “Cancer is a complicated disease, and too often we have tried to simplify it and simplify messages about it, to the point that we do harm to those we want to help.”
Breast cancer, the most common cancer in women, is a devastating and costly disease, striking more than 200,000 women annually and killing more than 40,000 women each year, reports the American Cancer Society. Prostate cancer is the most common form of cancer in men and the second most common cause of cancer death after lung cancer. This year, an estimated 192,280 men will be diagnosed with the disease and 27,360 men will die from it, according to estimates from the American Cancer Society.
The two diseases account for 26 percent of all cancers in the U.S., with an estimated 386,560 patients diagnosed annually.
Because of remarkable survival rates when the diseases are treated before they spread, screening for both cancers has been promoted on the assumption that early detection and treatment is the best way to reduce deaths. Consequently, much of the U.S. population undergoes routine screening for the cancers: About half of at-risk men have a routine prostate-specific antigen test, and 75 percent have previously had a PSA test. About 70 percent of women older than 40 report having had a recent mammogram. More than $20 billion is spent annually screening for the two diseases in the U.S.
The screenings have resulted in a “significant increase” in early cancers being detected, according to the article authors. Because of PSA testing, the chances of a man being diagnosed with prostate cancer have nearly doubled: In 1980, a white man’s lifetime risk of the cancer was one in 11; today it is one in six. Similarly, a woman’s lifetime risk of breast cancer was one in 12 in 1980; today it is one in eight. And, if ductal carcinoma in situ is included, the risk of being diagnosed with breast cancer, like prostate cancer, has nearly doubled as well.
But the authors found that while deaths have dropped for both cancers over the last 20 years, “the contribution from screening is uncertain.” They also found that many patients are undergoing treatment from cancers that actually pose minimal risk.
A comparison of prostate cancer incidence rates in the U.S. to the United Kingdom, where PSA screening has not been widely adopted, “did not result in significant differences in mortality,” the authors write. For breast cancer the relative reduction in deaths from screening has also been limited.
Yiwey Shieh, a medical student at the UCSF Medical School and former research assistant with Esserman, is a co-author of the article.
To learn more, visit www.ucsfbreastcarecenter.org .
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