Increasing utilization of regional nodal irradiation in elderly node-positive women and declining emphasis on demographic factors

To evaluate the practice patterns for the use of regional nodal irradiation (RNI) in treatment of elderly women with low volume node-positive breast cancer in the setting of breast conservation surgery (BCS).

Women aged 70-89 diagnosed with unilateral, pathologic T1-2N1M0 breast cancer from 2004 to 2013, who underwent BCS and received radiotherapy were identified from the National Cancer Database. In 2011, two major trials were presented that helped define indications for RNI. Patients were dichotomized into "early", i.e. diagnosed up to 2010, and "late" cohorts. Patient and treatment characteristics were compared between the cohorts and logistic regression used to determine independent factors associated with the receipt of RNI.

7228 women met inclusion criteria; 4330 (59.9%) in early and 2898 (40.1%) in late cohorts. Utilization of RNI increased from 33.9% in early to 42.5% in late cohorts (P ≤ 0.001) and was independent of a general increase in RNI utilization. RNI in the early and late cohorts was not different between the study population and younger women (P > 0.05). RNI utilization increased in both cohorts with increasing number of positive lymph nodes. In the early cohort, RNI was also associated with higher grade, white race and lower income. In the late cohort, RNI increased with the presence of multiple, predefined risk factors.

There was an increase in utilization of RNI for elderly patients from 2004 to 2013. In more recent years, the primary factors associated with receipt of RNI were tumor related with declining importance of demographic factors.