Causes of urban-rural disparities in adjuvant chemotherapy (AC) for rectal cancer (RC).

568 Background: While urban-rural differences in cancer care are well described, the etiology for such disparities is unclear. Our aim was to determine whether differences in AC use are mediated through variations in community size (CS) and whether differences in AC use translated into differences in patient survival outcomes (SO). Methods: Patients with stage II/III RC from 1999 to 2009 and referred to any 1 of 5 regional cancer centers in British Columbia were reviewed. Communities were classified as rural (R), small urban (SU), moderate urban (MU), and large urban (LU) based on census data. Using zip codes and a distance matrix application interface, driving distance (DD) to patients’ respective cancer center (CC) was determined and categorized into quartiles. Stepwise logistic regression was used to explore AC use based on urban-rural communities, controlling for DD. Cox regression was used to identify whether variations in CS translated into differences in SO. Results: A total of 2618 patients were i...