Biggest Risk of Aggressive Prostate Cancer Falls on Older and African American Men
February 12, 2013
Hong Zhang, M.D., Ph.D.
Even for people diagnosed with asymptomatic, early prostate cancer, the odds that their disease is high- or intermediate-risk and thus more aggressive is increased for people 75 and older and for African American men, according to a large, population-based study led by the University of Rochester Medical Center.
The findings represent the first suggestion that these two demographic groups might benefit the most from PSA (prostate-specific antigen) testing, which is designed to detect the cancer at an early stage, described in clinical terms as T1cN0M0. Physicians usually cannot feel tumors at this point, and they do not show up on imaging studies or cause symptoms. The URMC study indicates that a significant number of elderly and black men might be harboring an aggressive cancer that can only be diagnosed through a PSA test.
Lead author Hong Zhang, M.D., Ph.D., associate professor of Radiation Oncology at URMC and chief of Radiation Oncology at Highland Hospital, was invited to present the data at a Genitourinary Cancers Symposium organized by the American Society of Clinical Oncology (ASCO) in conjunction with the American Society of Radiation Oncology and the Society of Urologic Oncology, on Feb. 14-16, 2013, in Orlando. ASCO chose to showcase the URMC research at the meeting’s press program.
PSA screening is a controversial issue. In 2012 the U.S. Preventive Services Task Force recommended against PSA screening in all men – although a subsequent report from ASCO said that for men with a life expectancy of more than 10 years, the test has benefits that might outweigh the drawbacks.
Wrong assumptions about the life expectancy of older men have contributed to confusion among doctors and patients, however. In fact, nearly two-thirds of otherwise healthy elderly men can expect to live another decade once they reach age 75, perhaps making the test more relevant for them, said Edward M. Messing, M.D., study co-author, chair of Urology at URMC, and president of the Society of Urologic Oncology.
“If we stop PSA testing altogether we’d have no other way to detect aggressive prostate cancer sufficiently early in this group of high-risk patients,” Zhang said. “The findings of our study will help physicians and patients make more informed decisions on whether they want to proceed with PSA testing. However, more research and longer follow-up is needed to determine the effect of early detection and intervention on survival in these patients.”
Researchers analyzed data for 70,345 men in the United States with T1cN0M0 prostate cancer, which is believed to be the largest analysis of PSA-detected prostate cancer in the U.S. in the era of widespread PSA testing. They found that 47.6 percent had low-risk disease, 35.9 percent had intermediate-risk disease, and 16.5 percent had high-risk cancer. About 40 percent of all patients with high-risk disease were men older than age 75. In fact, in older men the odds of developing intermediate risk cancer were four times higher, and those of developing high-risk disease were nine times higher, compared to patients age 50 or younger.
African-Americans in all age groups were nearly twice as likely to develop high-risk disease, compared to white men.
Earlier research from the University of Rochester Medical Center also showed that more than 50 percent of prostate cancer deaths occurred in men who were initially diagnosed when older than 75, and that African Americans of all ages were twice as likely to face death from the disease.
Since the U.S. Task Force published its recommendations against testing, researchers have tracked a decline in PSA screening for all ages. ASCO’s decision aid for patients explains the available data and important considerations about PSA testing in lay language.
Prostate cancer is the second leading cause of cancer death among men; prognosis depends on whether the cancer has spread outside the prostate gland and the degree to which the cancer cells are abnormal. Risk levels are defined based on clinical stage at diagnosis, PSA level, and Gleason score. Patients have many treatment options, from actively watching the disease to surgery, radiation, and/or androgen deprivation therapy. Average 10-year survival rates are 91 percent for low-risk disease, 84 percent for intermediate, and 80 percent for high risk.
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