Minority of Older Patients With Low-Risk Prostate Cancer Managed by Observation


Key Points

  • A minority of patients had low-risk prostate cancer managed by observation.
  • Numerous factors affected the likelihood of upfront treatment, including whether diagnosing urologists performed the specific treatment.

Most older men with low-risk prostate cancer receive upfront treatment, despite absence of clear survival benefit and potential for morbidity. In a retrospective cohort study reported in JAMA Internal Medicine, Hoffman et al found that use of observation as management in this setting varied widely among urologists and radiation oncologists. Patients diagnosed by urologists who treat prostate cancer were more likely to receive upfront treatment, which was also likely to be a treatment that the urologist performed.

Study Details

The study involved 12,608 patients with low-risk prostate adenocarcinoma diagnosed between 2006 and 2009. Patient and tumor data were obtained from Surveillance, Epidemiology, and End Results (SEER) cancer registries. Data on diagnosing urologist, consulting radiation oncologist, cancer-directed therapy, and comorbid medical conditions were obtained from linked Medicare claims. Physician characteristics were obtained from the American Medical Association Physician Masterfile. Observation was defined as no cancer-directed therapy within 12 months of diagnosis.

Multivariate analysis of use of observation included age, race/ethnicity, comorbidity, clinical tumor category, and prostate-specific antigen (PSA) level. Medicaid coverage, SEER registry data, and urologist characteristics of decade of graduation, training location, degree, board certification, diagnosis volume, and treatment of prostate cancer were considered in the analysis using backward selection with a P value cutoff of .10.

Patients had a median age of 72 years and most were white (79.7%), had cT1 disease (73.4%), and were seen by a radiation oncologist (67.8%). Diagnoses were made by 2,145 urologists, of whom 88.2% treated low-risk prostate cancer. Overall, 80.1% of patients received upfront treatment and 19.9% received observation. Upfront treatments included prostatectomy in 15.4%, brachytherapy in 23.0%, external-beam radiation therapy in 29.1%, external-beam radiation therapy and brachytherapy in 6.2%, cryotherapy in 2.8%, and androgen-deprivation therapy in 3.6%.

Urologist and Patient Factors

The case-adjusted rate of observation among urologists ranged from 4.5% to 64.2% of patients. In multivariable analysis adjusted for patient-level and urologist-level characteristics, use of observation was less likely for urologists graduating before 1980 (odds ratio [OR] = 1.17, P = .04, for those graduating between 1980 and 1989; OR = 1.26, P = .004, for those graduating after 1989), for urologists with DO vs MD degrees (13.4% vs 20.1%, OR = 0.66, P = .01), and for those who treated low-risk prostate cancer (18.8% vs 25.0%, OR = 0.71, P = .01). Management with observation was not associated with urologist diagnosis volume on univariate analysis.

Use of observation increased with patient age, from 13.8% in those aged 66 to 70 years to 45.1% in those aged > 80 years (P < .001 for all age groups vs 66–70 years), was more likely in those with cT2 vs cT1 disease (24.4% vs 18.4%, OR = 1.23, P < .001), and was more likely in those diagnosed in 2008 (OR = 1.36, P < .001) or 2009 (OR = 1.76, P < .001) vs 2006. Patients seen only by urologists were more likely to undergo observation than those seen by a radiation oncologist and a urologist (43.8% vs 8.6%, P < .001). Overall, 70.8% of men who underwent observation saw only a urologist.

Multilevel analysis estimating the relative contributions of the diagnosing urologist and patient-level fixed effects to variance in the rate of observation indicated that the diagnosing urologist accounted for 16.1% of the variation in upfront treatment vs observation and that patient and tumor characteristics accounted for 7.9% of the variation.

Effect of Urologists’ Offering Treatment

Patients who received upfront treatment were more likely to undergo prostatectomy (23.8% vs 12.4%, P < .001), cryotherapy (22.0% vs 1.0%, P < .001), and brachytherapy (47.5% vs 21.0%, P < .001) if their urologist performed that treatment for non–low-risk disease. Patients with cancer diagnosed by urologists who billed for external-beam radiation therapy were more likely to receive external-beam radiation therapy (52.7% vs 42.9%, P = .005). Of 1,855 patients undergoing prostatectomy, 1,449 (78.1%) had the procedure performed by the diagnosing urologist.

Radiation Oncologist Factors

Overall, 7,554 patients met with 870 radiation oncologists. Of patients meeting with a radiation oncologist, 91.5% received upfront treatment and 8.5% underwent observation. For radiation oncologists treating ≥ 10 patients, case-adjusted rates of observation varied from 2.2% to 46.8%.

In multivariate analysis, radiation oncologists with MD vs DO degrees were more likely to use observation (P = .02). There was no association between observation and radiation oncologist treatment volume or decade of graduation. In multilevel analysis, 19.0% of the variance in upfront treatment vs observation choice was attributable to the radiation oncologist and 3.2% to patient characteristics.

The investigators concluded, “Rates of management of low-risk prostate cancer with observation varied widely across urologists and radiation oncologists. Patients whose diagnosis was made by urologists who treated prostate cancer were more likely to receive upfront treatment and, when treated, more likely to receive a treatment that their urologist performed. Public reporting of physicians’ cancer management profiles would enable informed selection of physicians to diagnose and manage prostate cancer.”

Karen E. Hoffman, MD, MHSc, MPH, of The University of Texas MD Anderson Cancer Center, is the corresponding author for the JAMA Internal Medicine article.

The study was supported by grants from the Cancer Prevention and Research Institute of Texas, National Cancer Institute, American Cancer Society, Duncan Family Institute, and The University of Texas MD Anderson Cancer Center. Benjamin D. Smith, MD, receives research support from Varian Medical Systems. Dr. Hoffman receives research support from the American Society for Radiation Oncology.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.