Specimens were obtained from 262 rectal cancer patients who underwent surgery in the SWLHD from 2000–2011. Clinicohistopathological data were collated and are summarized in Table 1. Standard radiotherapy treatments were at a dose of 25 Gy in 5 treatment fractions when performed alone or at 50.4 Gy in 28 treatment fractions when combined with 5 fluoro-uracil based chemotherapy. Short-term response to radiotherapy was measured by tumor regression grade (TRG) per the 7th edition of the American Joint Committee on Cancer (AJCC) manual  on a scale of 0 to 3: 0, complete response with no viable malignant cells; 1, moderate response with single or small groups of malignant cells; 2, minimal response with residual malignancy outgrown by fibrosis; 3, poor response with extensive residual malignancy. TRG 0, 1 and 2 were categorized as responders and TRG 3 as non-responders. Long-term response to radiotherapy was measured by survival outcomes including DFS and OS. Specimens obtained from primary surgery for rectal or rectosigmoid cancers were obtained from the South-Western Area Pathology database, Australia. Surgery consisted of total mesorectal excision, with anterior or abdominoperineal resection. Variables of interest included age, gender, pathological TNM stage, grade, vascular invasion, perineural invasion, tumor-infiltrating lymphocytes, and treatment. Outcomes of interest were DFS, OS and histologic TRG in the resected bowel for cases treated with neoadjuvant chemoradiation. DFS was defined as the time from diagnosis to first recurrence, if any. OS was defined as the time from diagnosis to last follow-up or death. Follow-up consisted of regular clinic visits, colonoscopy, blood tests, and imaging at the discretion of the treating specialist.