Increased utilization of postmastectomy radiotherapy in the United States from 2003 to 2011 in patients with one to three tumor positive nodes.

Abstract

There have been few recent studies that have examined the use of postmastectomy radiotherapy (PMRT) for patients with 1-3 positive nodes. We utilized the National Cancer Data Base to examine trends in PMRT for 346,218 patients with Stage I-III breast cancer from 2003 to 2011. Neoadjuvant therapy cases were excluded. Log linear models examined trends in PMRT and logistic regressions were used to examine factors related to PMRT. The proportion of pT1-2N1 patients receiving PMRT increased from 23.9% in 2003 to 36.4% in 2011 with an annual percent change (APC) of 6.2% (P < 0.001). There were significant increases in the use of PMRT amongst patients with one (APC = 7.7%), two (APC = 6.7%), and three (APC = 4.2%) positive nodes. In 2011, 27.8%, 43.8%, and 57.8% of patients with one, two or three positive nodes underwent PMRT, respectively. The number of positive nodes and tumor size were the strongest independent predictors of PMRT in the 1-3 node group; lymphovascular invasion, invasive lobular histology, and triple negative phenotypes were also associated with PMRT use. PMRT for patients with pT1-2N1 disease has increased with the greatest increase seen in those with one tumor positive node. Tumor factors remain strong independent predictors of PMRT.