Clinical Characteristics and Outcomes in Patients with Early-Onset Locally Advanced Rectal Cancer.

70 Background: Despite a reduction in both the incidence and mortality of CRC in the elderly population, recent studies have highlighted an increase in the incidence of early-onset CRC (EO-CRC). Clinical and prognostic data in this context are limited and conflicting. The aim of our study was to evaluate the clinical differences and outcomes of patients with early onset locally advanced rectal cancer. Methods: We retrospectively collected data from 305 patients affected by LARC treated in Italy at the Medical Oncology Units of the University Hospital of Cagliari, Istituto Nazionale dei Tumori Milan, and AOU Ospedali Riuniti Ancona. All patients underwent neoadjuvant chemoradiotherapy. The primary objective was overall survival (OS) while while secondary objectives were overall response rate (ORR) and major TRG. Results: Twenty five (8,2%) pts were EO-RC and 280 (91,8%) were LO-RC. In EO-RC the locations were distributed as follows: 9 (36%) lower rectum, 13 (52%) medium rectum, and 3 (12%) upper rectum. Pathologic responses were as follows: 3 (12%) TRG-0, 6 (24%) TRG-1, 10 (40%) TRG-2, and 6 (24%) TRG-3. While the radiological responses were as follows: 2 (8%) CR, 15 (60%) PR, 7 (28%) SD, and 1 (4%) PD. In LO-RC the locations were: 78 (27,8%) lower rectum, 153 (54,6%) medium rectum, and 49 (17,6%) upper rectum. Pathologic responses were as follows: 29 (10,4%) TRG-0, 60 (21,4%) TRG-1, 159 (56,8%) TRG-2, and 32 (11,4%) TRG-3. Radiological responses were as follows: 25 (8,9%) CR, 155 (61,4%) PR, 64 (22,9%) SD, and 19 (6,8%) PD. The 10 year overall survival was significantly higher in LO-RC patients compared to EO-CRC patients: 92.54% versus 70.83% (p = 0.0005). Conclusions: Compared to LO-RCs, EO-RC patients had more frequent low rectal tumors and higher rates of major pathological responses. Despite this, 10-year OS was found to be inferior in EO-RC. Further studies and insights will be necessary to better understand the biological and clinical characteristics of early-onset tumors.