Atlanta-Patients who undergo radical prostatectomy for clinical stage T4 prostate cancer have a higher survival rate than do patients who receive radiation or hormone therapies alone, and surgical prostate cancer patients' survival is comparable to that of patients who receive both hormone and radiation therapies.
Despite this evidence, radical prostatectomy is recommended only for a select group of cT4 patients, and surgery should not be considered the standard of care, according to the authors of a new study in Cancer (2006; 106:2603-9).
Researchers had yet to answer that question in the literature, so Dr. Johnstone and colleagues turned to the Surveillance, Epidemiology and End Results (SEER) database. They reviewed data from 1995 to 2001 of 1,093 patients presenting with cT4 disease. Using follow-up data from 2002, they analyzed post-diagnosis survival in five treatment groups: radical prostatectomy alone or in combination with other therapy; radiation therapy alone; hormone therapy alone; RT plus hormone therapy; and no treatment. Results were expressed as 1-, 3-, and 5-year observed survival and corresponding relative survival.
Researchers used a Cox proportionate hazards model to compare mortality across treatment categories. The model controlled for age, race, year of diagnosis, tumor grade, regional lymph node involvement, clinical tumor extension, and SEER registry.
"The number one finding is that relatively few patients with cT4 disease do undergo surgery, which is basically keeping with the standard of care," Dr. Johnstone said. "Of the hundreds of thousands of men who were diagnosed with prostate cancer during the study period, only 72 men underwent radical prostatectomy for cT4 disease."
Qualified survival benefit
The authors found that relative survival rates were lowest in the no-treatment group and highest in the RP group, and adding adjuvant radiation or hormone therapy to surgery offered no survival benefit.
The particular group of patients for whom the surgery increased survival most significantly was a small group who had positive regional lymph nodes. They represented nine of the 72 patients (13%) who had radical prostatectomy, according to Dr. Johnstone.
"What was also very interesting was that, at the time of surgery, about a third of the patients did not have cT4 disease when the actual prostatectomy specimen was reviewed," Dr. Johnstone said. "They actually had less disease, pathologically, than had been anticipated."
Of the 72 patients who had surgery, 31 had pathologic stage T4 disease, 24 had T3 or lower-stage disease, and 17 patients had an unknown pathology. The findings suggest that physicians are generally practicing evidence-based medicine when it comes to treating cT4 patients.
"There may be some patients for whom surgery makes sense, clinically, and, if that is the case and the patient is completely resected, this paper shows that there is no survival benefit to adding radiation or hormonal therapy at that point," Dr. Johnstone said.
He added that research examining the effects of combination therapies will help to resolve remaining questions surrounding the optimum treatment of cT4 patients.