Importance of Radiation Oncologist Experience Among Patients With Head-and-Neck Cancer Treated With Intensity-Modulated Radiation Therapy

Abstract

Purpose: Over the past decade, intensity-modulated radiation therapy (IMRT) has replaced conventional radiation techniques in the management of head-and-neck cancers (HNCs). We conducted this population-based study to evaluate the influence of radiation oncologist experience on outcomes in patients with HNC treated with IMRT compared with patients with HNC treated with conventional radiation therapy.

Methods: We identified radiation providers from Medicare claims of 6,212 Medicare beneficiaries with HNC treated between 2000 and 2009. We analyzed the impact of provider volume on all-cause mortality, HNC mortality, and toxicity end points after treatment with either conventional radiation therapy or IMRT. All analyses were performed by using either multivariable Cox proportional hazards or Fine-Gray regression models controlling for potential confounding variables.

Results: Among patients treated with conventional radiation, we found no significant relationship between provider volume and patient survival or any toxicity end point. Among patients receiving IMRT, those treated by higher-volume radiation oncologists had improved survival compared with those treated by low-volume providers. The risk of all-cause mortality decreased by 21% for every additional five patients treated per provider per year (hazard ratio [HR], 0.79; 95% CI, 0.67 to 0.94). Patients treated with IMRT by higher-volume providers had decreased HNC-specific mortality (subdistribution HR, 0.68; 95% CI, 0.50 to 0.91) and decreased risk of aspiration pneumonia (subdistribution HR, 0.72; 95% CI, 0.52 to 0.99).

Conclusion: Patients receiving IMRT for HNC had improved outcomes when treated by higher-volume providers. These findings will better inform patients and providers when making decisions about treatment, and emphasize the critical importance of high-quality radiation therapy for optimal treatment of HNC.

Fig 1.

Patient selection process. HNC, head-and-neck cancer; NPI, National Physician Identifier; UPIN, Unique Physician Identification Number.

Fig 2.

Overall survival for patients with head-and-neck cancer receiving intensity-modulated radiation therapy stratified by high- versus low-volume providers.

Fig 3.

Impact of radiation provider volume on survival and toxicity after radiation stratified by (A) conventional radiation (n = 3,970) or (B) intensity-modulated radiation therapy (n = 2,242). The points on the plot represent adjusted hazard ratios and subdistribution hazard ratios for the impact of provider experience. *In the case of all-cause mortality, the adjusted hazard ratio is presented, whereas for all other outcomes the adjusted subdistribution hazard ratio is presented. Horizontal bars represent 95% CIs and P-values are reported on the right. Numbers in parentheses represent number of events.

Fig A1.

Impact of radiation provider volume on overall survival of patients treated with intensity-modulated radiation therapy (n = 2,242). Relative change in overall survival associated with providers who treat more or fewer patients with head-and-neck cancer. These numbers represent an extrapolation of the hazard ratio for provider volume in the multivariable Cox proportional hazards regression model for overall survival. For example, for every 10 additional patients treated by a radiation oncologist, the relative risk of death decreases by 37%.

Fig A2.

Subgroup analysis evaluating the impact of radiation provider experience on the cohort of patients with head-and-neck cancer treated with intensity-modulated radiation therapy ( = 2,242). Plot represents the results of multivariable Cox proportional hazards regression models for overall survival among select subgroups. Each dot on the plot represents the adjusted hazard ratio for provider experience. Hazard ratios less than 1 imply that higher provider volume was associated with a decreased risk of death.