Two decades after the explosion in cancer screening fueled by reimbursement for mammography and prostate specific antigen (PSA) testing, a new analysis suggests that it is time to rethink the push for early detection of these two cancers.
There is no argument that more cancers are being detected and at a much earlier stage, but that increase has not resulted in a decrease in metastatic disease, according to Laura Esserman, MD, MBA, of the University of California, San Francisco, and colleagues, who made their case in a special communication published in the Oct. 21 issue of the Journal of the American Medical Association.
In broad strokes they painted a picture of increased detection and costly treatment of cancers that pose minimal risk, without making a dent in killer cancers.
The researchers touched a nerve with the commentary, and the American Cancer Society has already gone on record saying that it is reconsidering its position on the risks and benefits of breast and prostate cancer screening.
Otis Brawley, MD, chief medical officer of the society told The New York Times, that the benefits of screening have been exaggerated.
In the JAMA paper, Esserman wrote that the screening push seemed like a logical way to reduce cancer mortality. For both breast and prostate cancer "there are remarkable differences between outcomes of localized versus advanced disease (breast cancer: five-year relative survival rates of 98.1% versus 27.1%; prostate cancer: 100% versus 31.7%)."
And the penetration of the screening has been significant -- 70% of women 40 or older say they have had a recent mammogram, and 50% of at-risk men have routine PSA testing.
But when prostate cancer mortality in the U.S. was compared with the rate in U.K. -- where PSA screening is not recommended -- there was no difference, although the incidence of prostate cancer was dramatically higher in the U.S.
For breast cancer, seven randomized trials found a relative reduction in mortality ranging from 20% to 30%, but the "observed decrease in mortality is attributable to both screening and adjuvant therapy, with an estimated decrease of 7% to 23%, and 12% to 21%, respectively."
Esserman suggested that the problem may be that early detection "may not be the solution for aggressive cancers because many may not be detected early enough for a cure."
What is an effective screening technique is the detection of premalignant lesions, which is exactly what occurs with both colonoscopy and pap smears, two screening strategies that have significantly decreased invasive colorectal and cervical cancers.
Esserman argued that it is time to develop new screening strategies -- possibly new biomarkers -- that will be able to differentiate between "significant- and minimal-risk cancers."
At the same time, she recommended new strategies to "reduce treatment for minimal-risk disease" and called for the development of "clinical and patient tools to support informed decisions about prevention, screening, biopsy, and treatment, and offer treatments tailored to tumor biology."
Primary source: Journal of the American Medical Association
Source reference: Esserman L et al "Rethinking Screening for Breast Cancer and Prostate Cancer" JAMA 2009; 302: 1685-1692.