On the heels of the American Cancer Society's recent controversial response to breast and prostate cancer screenings guidelines, a new study from the Mayo Clinic has emerged analyzing the correlation between prostate-specific antigen (PSA) levels and prostate size. The study discovered that routine annual evaluation of prostate growth does not predict the development of prostate cancer. The study also suggests that a rapidly rising PSA level should automatically prompt a biopsy to determine the possibility of prostate cancer.
Dr. David B. Samadi, Chief of Robotics and Minimally Invasive Surgery at The Mount Sinai Medical Center in New York City, agrees. To date, Dr. Samadi has performed over 2,100 robotic prostatectomy procedures, making him one of the most experienced prostate cancer surgeons in the world. He believes that the change in prostate size should not determine the decision to biopsy the gland for cancer. "It's the rising, or rapidly fluctuation PSA level, among other indicators, that should prompt the decision to investigate the possibility of cancer further," stated Dr. Samadi.
The study, based on data in the Olmsted County Study of Urinary Health Status among Men, followed the prostate examinations of 616 men between the ages of 40 and 79, who did not have prostate disease, every two years for 17 years. Out of the study group, 9.4 percent of the subjects developed prostate cancer. Those who were diagnosed had a faster rise in PSA levels, at an increase of 6 percent per year. Those who were not diagnosed with cancer only experienced an increase of 3.3 percent per year. Interestingly, the increase in prostate size was similar between these two groups, with a change of 2.2 percent per year.
"What the study seems to demonstrate is that there is no relationship between the growth rate of the prostate and the rise in PSA levels," concluded Dr. Samadi. However, the study indicated that a rising PSA level alone prompted the need for a biopsy to determine the likelihood of cancer. "Of course rising PSA levels are a great concern, but the amount of fluctuation between the numbers is what I look for when determining the need for a biopsy in my patients," said Dr. Samadi.
Dr. Samadi, an experienced oncologist and robotic surgeon, takes into account not only three sets of recent PSA screenings, but also a digital rectal exam (DRE) and Gleason scores (which classifies the stage and grade of prostate cancer). The disease progresses differently in every patient. Therefore, these three numbers, factored in with age and family history, are what give Samadi a clearer picture of what kind, stage, level and progression of prostate cancer he is dealing with.
Additionally, the study followed the subjects on their prostate exams every two years. "It's no surprise that a PSA level should rise so high in two years, which is why I use a variation of testing factors to determine a baseline for fluctuations, as well as recommending screenings annually, sometimes bi-annually for patients with high risk factors," said Dr. Samadi.
This method appears to be upheld in another recent international study by the Fox Chase Cancer Center in Philadelphia. The findings showed that patients who had undergone radiotherapy and experienced a rapid PSA level rise within 18 months were more likely to die from the disease. Early PSA failure predicted more than a 25 percent decline in five-year survival rate of the group compared with failure after 18 months. In a separate analysis for this particular study group, the time to PSA failure overrode Gleason score, tumor stage, age and PSA doubling time as a predictor of mortality. Even though the study group had been diagnosed with cancer and treated with radiotherapy, the findings indicated that it is not advisable to wait until the PSA rises or other clinical evidence manifests itself. Initiating treatment sooner without waiting for other signs or symptoms of prostate cancer is the best course of action.
"The take-away message for both of these studies is first that PSA levels and prostate growth rates work independently of each other, and second that the length of time that PSA levels are not actively monitored, and allowed to fluctuate and rise, can deeply impact mortality," concluded Dr. Samadi.