Sep. 14, 2009 Appropriately selected prostate cancer patients, including older men and men with small, low-risk tumors, may safely defer treatment for many years with no adverse consequences, according to a new study in the Journal of Clinical Oncology (JCO). Led by researchers at Beth Israel Deaconess Medical Center (BIDMC), the study appears online today.
"With the advent of PSA [prostate antigen] screening nearly 20 years ago, we started to detect prostate cancers at much earlier stages," explains corresponding author Martin Sanda, MD, Director of the Prostate Cancer Center at BIDMC and Associate Professor of Surgery at Harvard Medical School.
"Consequently, while PSA testing has enabled us to successfully begin aggressive treatment of high-risk cancers at an earlier stage, it has also resulted in the diagnosis of cancers that are so small they pose no near-term danger and possibly no long-term danger," he adds.
Sanda, together with coauthors from Brigham and Women's Hospital, the Harvard School of Public Health and the University of California, San Francisco, looked at the Health Professionals Follow-Up Study, a large cohort study comprising 51,529 men who have been followed since 1986. Every two years, the participants respond to questionnaires inquiring about diseases and health-related topics, including whether they have been diagnosed with prostate cancer.
A total of 3,331 men reported receiving a diagnosis of prostate cancer between 1986 and 2007. Further analysis found that among this sub-group, 342 men – just over 10 percent – had opted to defer treatment for one year or longer. Ten to 15 years later, half of the men who had initially deferred treatment still had not undergone any treatment for prostate cancer.
"We wanted to find out how this group of men fared in the long-term," explains Sanda. "So we looked at the data they provided us at an average of eight years after their initial diagnosis, and compared it with data provided by prostate-cancer patients who had opted for aggressive treatment, such as surgery, radiotherapy or hormonal therapy.
"We found that the deaths attributed to prostate cancer were very low among the men with low-risk tumors," explains Sanda. "Our analysis showed that only two percent of the men who deferred treatment eventually died of the disease, compared with one percent of the men who began treatment immediately following their diagnosis. This is not a statistically significant difference."
There are three types of prostate cancer: High risk, which are large, faster-growing cancers; intermediate risk; and low-risk, which are small and slower growing cancers. While there is ample evidence that treating intermediate and high-risk cancers with either surgery, radiation or hormone therapy can save lives, whether and how best to care for low-risk cancers remains uncertain.
"These findings showed that men diagnosed with low-risk tumors who deferred treatment were still doing fine an average of eight years -- and up to 20 years -- following their diagnosis.
"Only half of these men wound up undergoing any treatment 10 to 15 years post-diagnosis," says Sanda. "This means that they were able to avoid the disruption in their quality of life which might have occurred had they undergone immediate treatment.
"If this approach was more broadly accepted as a standard care option for suitable low-risk prostate cancers, it might help us avoid throwing the baby out with the bathwater when it comes to the PSA test," he adds. "Instead of just abandoning the PSA test because it might be leading to an overdiagnosis of prostate cancer, we could conduct PSA screening in a way that allows more aggressive prostate cancers to be treated, while less aggressive tumors could initially be monitored. This would avoid problems due to treatment of 'overdiagnosed' low-risk cancers, while preserving the lifesaving benefits of treating aggressive cancers that have been detected through PSA testing."
Study coauthors include BIDMC investigator William V. Shappley III; Stacey A. Kenfield, and Julie L. Kasperzyk of the Harvard School of Public Health (HSPH); Weiliang Qiu and Meir J. Stampfer of Brigham and Women's Hospital and HSPH; and June M. Chan of the University of California, San Francisco.
This study was funded by grants from the National Institutes of Health.
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