Nov. 1, 1999 (Cleveland) -- Patients with prostate cancer whose prostate-specific antigen (PSA) blood levels return to normal range and stay there for at least 5 years after radiation therapy have a high likelihood of being cured of their cancer, according to this study that appears in the Oct. 15 issue of Cancer, a journal published by the American Cancer Society.
Prostate cancer is the most common cancer in men, and the second most fatal. According to figures from the American Cancer Society, 179,300 men will be diagnosed with prostate cancer in 1999, and 37,000 will die from the disease. Although prostate cancer has few, if any, symptoms in its early stages, it is highly treatable. Therefore, the American Cancer Society recommends annual PSA screening and digital rectal examinations in all men aged 50 and older.
In patients who are diagnosed with prostate cancer and undergo treatment, including surgery or radiation therapy, PSA testing is used to determine the effectiveness of treatment. PSA levels below 4.0 are considered normal.
These authors found that patients have a high likelihood of cure if their PSA levels remain normal for about three and a half years following treatment, and rarely have treatment failure if they do well for four years after radiation therapy. In those patients in whom radiation treatment failed, 95% had increasing PSA levels during the first four years after treatment.
"When we treated patients for prostate cancer in the past, we were not able to tell them whether or not they were cured. We could tell them, at treatment initiation, how effective the treatment could be, but we never really knew at what point we could tell them that they were cured," says study co-author Frank A. Vicini, MD, who is at the William Beaumont Hospital in Royal Oak, Michigan, where he performed this study with his colleagues.
But before confirming that treatment has been completely successful, physicians must follow these patients for a sufficient time, Vicini cautions WebMD, especially those with lower PSA levels. Surprisingly, patients with higher PSA levels, which are associated with more advanced cancer, showed treatment failures sooner than those with lower levels, which are associated with cancers that are not as advanced. The authors, therefore, recommend longer follow-up for patients who have a more favorable outlook before radiation therapy to make sure the cancer does not recur.
"[If patients] started out with a very aggressive cancer (high PSA), it will take less time to determine whether they are cured. Conversely, if they have a less aggressive cancer (a lower PSA), it may take a little bit longer before we can say to them that we're 95% certain that they are cured," Vicini tells WebMD.
Furthermore, the longer it took to achieve normal PSA levels, the better the prognosis, according to these results. Patients who took at least 2 years or more to achieve these normal PSA levels after treatment had the best chance of being completely cured of their cancer.
These results give doctors something more concrete to tell patients, says Vicini, who is a professor of radiation oncology. "This is important in terms of what you can tell your patients, and in terms of evaluating treatment effectiveness. We always wondered how long you have to follow patients after a particular treatment before you can tell them that it works. So this is now giving us a very good idea of how long you have to follow up people. We now have the ability to tell patients with a reasonable degree of certainty that if their PSA has remained at the right level for four or five years, it means that they are probably cured," he concludes.