Researchers at the Oregon Health & Science University Cancer Institute and the Portland Veterans Affairs Medical Center have found a way to identify which men need a second prostate biopsy because they may be harboring one of the more life-threatening prostate cancers even though they were given a clean bill of health after their first biopsy.
Shane Rogosin, M.D., one of the lead study investigators will present the research on Saturday, June 2 at 1:45 a.m. CDT at the 43rd annual meeting of the American Society of Clinical Oncologists in Chicago. Rogosin is a resident in general internal medicine, OHSU School of Medicine.
"There are several known limitations to the prostate biopsy procedure, all of which can give a falsely negative result. These factors include the inability to see the cancer on imaging, the presence of benign prostate enlargement and the small amount of tissue taken during the needle biopsy," Rogosin said.
Also involved in the research is Mark Garzotto, M.D., the director of urologic oncology at the Portland Veterans Affairs Medical Center, Associate professor of surgery (urology) in the OHSU School of Medicine, and member of the OHSU Cancer Institute.
"Until now we've really had no clear and consistent method to recommend further follow up or diagnostic procedures for men who have a negative biopsy. We have derived a simple marker so clinicians can identify who is at risk for high-grade prostate cancer," Garzotto said.Rogosin studied what is considered a large group, 511 male subjects, at the Portland Veterans Affairs Medical Center from 1992 to 2006. All had been referred for a suspicion of prostate cancer. All patients had one prior negative prostate biopsy. In all, the study included 1,319 biopsies. The study was designed to determine which factors predicted that a man would have one of the more life-threatening cancers (or high-grade) on a repeat biopsy. A host of factors were examined including age, family history, body weight, prostate–specific antigen (PSA) levels and prostate size. What the researchers found to be the most powerful indicator for a repeat biopsy was a high PSA adjusted for prostate size, also known as PSA density.
"What we worry about is which men may have high-grade cancer. Now we can prescribe a second biopsy for a few months later. We know that this is a judicious use for a biopsy," Garzotto said.
Besides identifying which men may have a deadly form of prostate cancer this new finding could also reduce the rates of cancer overtreatment and the number of unnecessary biopsies.
Prostate biopsies can cause patient anxiety, pain, bleeding and infection, and can lead to a significant increase in medical and non-medical costs to health care systems and patients.
This study is particularly meaningful because of the large sample size of patient cases, and it is longitudinal, which means researchers were able to study the patients for many years.
Prostate cancer is the most common visceral cancer and the second leading cause of cancer-related death in men in the United States. It is estimated that there will be 218,890 new cases diagnosed in 2007, and 27,050 men will die from prostate cancer this year in the United States.
More than 1 million prostate biopsies are performed each year. Of those, only about 25 percent test positive for cancer. However, another 25 percent are given a false negative, meaning that no cancer is detected even when later it is found that the patient does have cancer.
The OHSU Cancer Institute is the only cancer center designated by the National Cancer Institute center between Sacramento and Seattle. It comprises some 120 clinical researchers, basic scientists and population scientists who work together to translate scientific discoveries into longer and better lives for Oregon's cancer patients. In the lab, basic scientists examine cancer cells and normal cells to uncover molecular abnormalities that cause the disease. This basic science informs more than 200 clinical trials conducted at the OHSU Cancer Institute.