Results from the large, randomized PIVOT clinical trial that were published in 2012 initially showed that at a median follow-up of 19 years, radical prostatectomy neither improved overall survival nor reduced death related to prostate cancer compared with “watchful waiting” in men with low-risk disease.
However, when these results were published, there was a concern about the generalizability of the results, because of the poorer-than-average overall health of the patients who participated in the PIVOT trial.
Stephen A. Mihalcik, MD, PhD, Clinical Fellow, Harvard Radiation Oncology Program, Boston, analyzed the impact of the previously reported PIVOT results by looking at oncology practice patterns before and after the publication of the results from the trial. He reported his new study results at the 2016 Genitourinary Cancers Symposium.
“The study did not directly ask whether doctors are using PIVOT results to guide practice. We looked at practice patterns 15 years before PIVOT and 1 year after PIVOT,” Dr Mihalcik explained.
Dr Mihalcik’s study showed that during the period after the publication of the PIVOT trial results, men with low-risk or favorable intermediate-risk prostate cancer whose health was poorer than the national average were less likely to undergo curative treatment than other men with prostate cancer, whereas men at higher risk for harboring occult high-grade prostate cancer, despite favorable-risk characteristics, were more likely to undergo curative treatment.
“The use of curative therapy was lower among low-risk men who may not benefit from curative treatment, but there is a risk of undertreating men who may be at high risk,” said Dr Mihalcik.
“And there is the possibility that you may overtreat patients who are at risk to die from other causes, such as cardiovascular disease. We want to be sure we are not undertreating high-risk men or overtreating low-risk men. These results are consistent and reassuring, because they are in line with results of PIVOT,” he said.
The new study was based on 6818 men with low-risk (75%) or favorable intermediate-risk (25%) prostate cancer who were treated with curative intent at the Prostate Cancer Foundation of Chicago. The investigators compared the proportion of men with ≥2, 1, or 0 comorbidities, which were restricted to cardiovascular (CV) comorbidities, including myocardial infarction, congestive heart failure, diabetes mellitus, and coronary heart disease.
Of the 6818 men, 5208 had CV comorbidities; 4.3% had ≥2 CV comorbidities, 19.2% had 1 CV comorbidity, and 76.5% had 0 CV comorbidities.
Before the publication of the results of PIVOT, an increasing proportion of men with ≥2 comorbidities received curative treatment over time, whereas 1 month after the study’s results were published, a decline was observed in the proportion of men with the greatest comorbidity (5.4% vs 2.9%; P = .005).
Men who received curative treatment after the publication of PIVOT were significantly more likely to be younger (P = .04), be black or Hispanic (P = .003), and have favorable intermediate-risk prostate cancer than low-risk prostate cancer (P = .007).