Photo by Todd McNaught
New research from the Public Health Sciences Division finds that African- American men with prostate cancer are half as likely to receive annual blood tests to monitor their disease compared to Caucasian men, a factor that may contribute to the poor survival rates among black men with the disease.
The analysis of more than 650 men with localized prostate cancer is the first to show that frequency of prostate-specific antigen (PSA) test surveillance following diagnosis is associated with race. The study adds to a growing body of evidence indicating that disparities in health-care access likely contributes to differences in prostate-cancer mortality rates between black and whites. On average, the researchers found that African-American men received three PSA tests for every four tests received by Caucasian men.
Steven Zeliadt and Dr. Ruth Etzioni led the study, which they designed originally to describe the patterns and frequency with which PSA surveillance is used to monitor progression or recurrence of prostate cancer in men with localized disease, a practice for which no established guidelines currently exist. Although surveillance has become routine, the value of such testing is unknown.
Greater need, fewer tests
As the researchers began to analyze their data, they were struck by significant differences in testing frequency among African-Americans and Caucasians, said Zeliadt, a graduate student at the University of Washington School of Public Health and Community Medicine who is conducting his thesis research with Etzioni.
"What was shocking to us is that it is known that African-American men typically present with more advanced disease," he said. "Because of that, we would have expected to see more frequent testing in those men."
The study was published in the August 1 issue of Cancer and involves collaborators from the Veterans Affairs Puget Sound Health Care Systems of Seattle and West Haven, Conn.; the UW Department of Urology and Yale University.
The PSA test measures the blood level of the prostate-specific antigen, a protein released by prostate tumors. Men diagnosed with cancer, regardless of their initial treatment, undergo follow-up PSA testing to monitor for evidence of disease progression or recurrence. The test also is commonly used to screen healthy men for prostate cancer, although previous studies from Etzioni and others have found that the test likely "overdiagnoses" men who otherwise would never develop symptoms of the disease.
Although the PSA test was originally designed to track disease progression, researchers haven't demonstrated whether such surveillance affects a patient's survival. For that reason, guidelines regarding testing frequency have been difficult to establish.
Zeliadt's doctoral research attempts to address how PSA surveillance impacts such outcomes as survival and initiation of androgen-deprivation therapy, a treatment that inhibits the production of male hormones that stimulate tumor growth.
"There are many questions regarding the outcomes of PSA surveillance," Etzioni said. "A rise in PSA often leads to secondary treatment, and it is not known whether such treatment improves a man's survival or quality of life. We do know that it takes a long time-about eight years-from the time a man's PSA level rises until he develops symptoms of recurrence."
The study was based on medical data for 658 men from New Haven and Hartford, Conn., collected by study co-author Dr. David Penson at the Veterans Affairs Puget Sound Health Care Systems of Seattle. The men were diagnosed with localized prostate cancer and treated either with radical prostatectomy (removal of the prostate) or radiation therapy or had received no therapy and were undergoing "watchful waiting" to determine whether the cancer would progress. Forty-five providers at four area hospitals treated the men.
Patients' medical records were examined to determine age at diagnosis, race, disease stage, PSA level at diagnosis, treatment and dates and results of PSA tests subsequent to diagnosis. African-American men, who made up 7 percent of the study population, tended to have more advanced disease at diagnosis than Caucasian men.
After a median follow-up period of 6.6 years, researchers found that the average time to the first PSA test after diagnosis was 6.2 months for the surgery group, 10.8 months for the radiation-therapy group and 13.7 months for the watchful-waiting group. More than 70 percent of the men received at least one test annually, although the researches noted considerable variation in PSA-testing practice after diagnosis. Men who received more frequent testing were more likely to subsequently receive secondary therapy.
African-American men were found to be half as likely as Caucasians to receive annual PSA monitoring. Overall, blacks received three PSA tests for every four tests given to whites.
Etzioni said that although the impact of post-diagnostic PSA surveillance on survival is unclear, the study results are consistent with other research that suggests that disparities in health-care access may contribute to the poorer survival of black prostate-cancer patients compared to whites. Other research has found similar trends for disparity between races for post-diagnostic surveillance of breast cancer.
"Research shows that African-Americans appear to receive aggressive treatment less frequently, and our data is certainly consistent with that," she said. "We need to be working hard to eliminate these disparities."
Etzioni and Zeliadt next plan to conduct a much larger study of PSA surveillance that will involve data collected from 11 cancer registries around the country linked with Medicare treatment records.