NEW YORK – Men who show signs that their disease has returned after prostate cancer treatment are still more likely to die of other causes, a new study in US veterans shows.
Nevertheless, researchers say the study underscores the need to find a better way to identify the minority of men who will die of prostate cancer after disease recurrence.
"We often don't know what to tell these men in terms of their risk of dying of prostate cancer," Dr. Timothy Daskivich of the University of California, Los Angeles, told Reuters Health.
Detecting prostate cancer is most often done with a blood test that measures concentrations of prostate-specific antigen, or PSA, a protein made in the prostate that becomes elevated in men with prostate cancer.
After treating prostate cancer with surgery or radiation, PSA levels are monitored. If PSA levels begin to increase, this can serve as an early indicator of disease recurrence. But the effect of a rising PSA after treatment — also known as "biochemical recurrence" — on men's subsequent risk of dying from prostate cancer is not clear.
To investigate, Dr. Edward M. Uchio of the VA Connecticut Healthcare System in West Haven and Yale University School of Medicine in New Haven and his colleagues looked at 623 men who had been diagnosed with prostate cancer between 1991 and 1995 and were followed for up to 16 years after treatment.
By the end of 2006, 387 of the men (62 percent) had died; 48 of these deaths, or 12 percent, were due to prostate cancer, the researchers report in the Archives of Internal Medicine.
Among the 225 men who had surgery to remove their prostate, 37 percent had biochemical recurrence (rising PSA) within 15 years of treatment. For these men, the risk of dying was 3 percent within 5 years of treatment, 10 percent within 10 years of treatment, and 21 percent at 15 years' follow-up.
Among the 398 men treated with radiation, 48 percent had experienced recurrence at 15 years. The risk of dying for these men was 11 percent at 5 years, 20 percent at 10 years, and 42 percent at 15 years.
The relatively low probability of dying from prostate cancer "may provide some reassurance, and perhaps improve the quality of life, among men facing this situation," Uchio and his team say.
They add: "The phrase 'most men die with prostate cancer, not of it,' applies to elderly veterans, even after failure of primary treatment."
Efforts, the researchers say, should focus on finding better ways to identify those men who are more likely to die of their disease, for example by looking at how quickly the PSA level doubles over time, the researchers note.
"We can't just look at these PSA levels and based upon those jump in and retreat the patient," Dr. Richard J. Ablin, of the University of Arizona College of Medicine in Tucson and co-author of an editorial published with the study, told Reuters Health.
The time it takes for the PSA level to double, rather than just whether those levels climb above a certain threshold, is a much better way to identify the highest risk men, he said.
A man's overall health should also be taken into account in deciding what type of treatment he receives for prostate cancer recurrence, according to Ablin.
Daskivich and his colleagues have developed and tested a questionnaire to do just that. "Our study is really looking at trying to help men who are very sick for other reasons to decide whether they want to pursue treatment in the first place," Daskivich explained in an interview with Reuters Health.
He and his colleagues followed for an average of 6 years 2,900 men who had completed the Total Illness Burden Index for Prostate Cancer, or TIBI-CaP, questionnaire, which takes just 15 minutes to complete.
During follow up, 420 men (14.5 percent) died, but only 86 (3 percent) died of prostate cancer.
The investigators found that men with the highest scores on the TIBI-CaP, meaning that they had illnesses that severely impacted their daily lives (for example, shortness of breath with exertion), were 10 times more likely to die of a cause other than prostate cancer than men with the lowest scores.
Forty-one percent of the men with the highest TIBI-CaP scores had died from other causes within 6 years of treatment, compared to just 6 percent of the healthiest men.
This is well before the benefits of aggressive treatment, for example radiation or surgery, would be apparent, the researchers note. These men "may wish to strongly consider conservative over aggressive treatment," Daskivich and his colleagues write in the Archives of Internal Medicine.
They conclude that men with other illness in addition to prostate cancer "ought to be offered this simple questionnaire to inform their decision making."