LOS ANGELES – A study of 11,453 men diagnosed with local prostate cancer from 1999 to 2001 found that brachytherapy reduced their relative risk of dying from the disease by 55%, compared with watchful waiting.
Radical prostatectomy was the best option and hormone therapy was the worst in the complex analysis reported by Dr. Esther H. Zhou at the annual meeting of the American Society for Therapeutic Radiology and Oncology. External beam radiation therapy also was better than watchful waiting (sometimes known as active surveillance), but the difference was not statistically significant.
“The results indicate brachytherapy is better than watchful waiting for the patient, even after we adjust for age, comorbidity, and… Gleason score,” Dr. Zhou, an epidemiologist at Case Western Reserve University, Cleveland, told reporters at a press briefing. “We want to emphasize that brachytherapy is as good as radical prostatectomy and better than watchful waiting.”
She described the study as the first large, population-based comparison of brachytherapy with watchful waiting, and said the researchers were surprised to find that brachytherapy produced a higher rate of disease-specific survival. The best choice among prostate cancer treatments is highly controversial, with options ranging from surgically removing the prostate to doing nothing while monitoring the slow-moving disease for signs of progression.
Brachytherapy involves small radioactive seeds that are placed into the prostate by a radiation oncologist. Unlike external beam radiation therapy, the procedure can be done in one visit. It also is less arduous and has a faster recovery than does radical prostatectomy, which is often reserved for patients who are relatively young and physically fit.
Dr. Zhou and her colleagues examined the records of newly diagnosed prostate cancer patients aged 65 years and older in the Ohio Cancer Incidence Surveillance System and linked them with Medicare and death certificate files. She said that the Ohio database is comparable to the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registry. The investigators assigned patients who did not receive a curative therapy within 6 months of diagnosis to the watchful waiting category.
At 7 years, disease-specific survival–the percentage of patients who didn't die of the disease–was highest for radical prostatectomy (97.9%), followed closely by brachytherapy (96.6%) and external beam radiation (94.2%). Watchful waiting (89.8%) and androgen deprivation therapy (88.1%) were not as effective, according to Dr. Zhou.
When the investigators conducted a multivariate analysis taking into account age, disease stage, comorbidities, and Gleason score, they found that radical prostatectomy (hazard ratio 0.25) and brachytherapy (HR 0.45) were significantly better than watchful waiting, which was assigned a hazard ratio of 1. “For the same age of patient with the same Gleason score with the same stage, [those who receive brachytherapy] tend to have better survival” than do those treated with watchful waiting, Dr. Zhou said.
External beam radiation therapy also was better than watchful waiting (HR 0.66), she added, but the difference was not statistically significant. Again, androgen-deprivation therapy produced the worst results (HR 1.32), compared with watchful waiting.
Dr. Zhou noted, however, that the database did not include information on prostate-specific antigen levels, which would be a factor in the choice of treatment.
The investigators had no disclosures.