Radiotherapy with chemotherapy for rectal cancer reduces local recurrence risk. Of 113 patients (59 male, 54 female) undergoing treatment at New York Presbyterian Hospital, 1998-2007, 6 discontinued radiotherapy; all were female. Females were also more likely to have a treatment interruption (35% vs 12%, p = .004). Other factors associated with treatment interruption included adjuvant versus neoadjuvant therapy (OR 14.08, 95%CI 1.55-127.87), use of capecitabine versus 5-fluorouracil (OR 75.90, 95%CI 3.33->999), and development of any adverse event (OR 20.66, 95%CI 1.76-242.12). While radiotherapy discontinuation was uncommon in our cohort, for unknown reasons, females were more likely to discontinue or interrupt treatment.