Correlates and trends of IMRT use in locally advanced rectal cancer

Three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT) are both utilized in rectal cancer treatment. We investigated the impact of demographic and clinical factors for the selection of each modality utilizing the National Cancer Database. Adult patients with stage II and stage III adenocarcinoma of the rectum diagnosed from 2004 to 2013 were included. Chi-squared analysis was used to compare demographic and clinical variables in the 3DCRT and IMRT treatment groups. Univariate and multivariate logistic regression modeling was used to identify factors predictive of receipt of each radiation therapy (RT) modality. A total of 9027 patients were identified: 8141 in the neoadjuvant RT group and 886 in the adjuvant RT group. In both cohorts, the utilization of IMRT increased over the study period (p < 0.01). Factors predictive of receiving IMRT on multivariate analysis include non-white race (OR 1.28, 95 % CI 1.12-1.48 for neoadjuvant RT, OR 1.72, 95 % CI 1.08-2.72 for adjuvant RT) and West, Northeast, and South geographic regions. Other factors predictive of receiving IMRT in the neoadjuvant setting include treatment at an academic institution (OR 1.15, 95 % CI 1.03-1.28) and radiation dose > 5400 centigray (cGy) (OR 2.07, 95 % CI 1.69-2.53). The use of IMRT for locally advanced rectal cancer is increasing and surpassed 3DCRT as the most common radiation modality at the beginning of 2010. Intensity-modulated radiotherapy was given more commonly for adjuvant treatment than for neoadjuvant treatment and was associated with higher RT doses and treatment at an academic institution in the neoadjuvant setting.