Rectosigmoid Junction Cancer; The Role of Preoperative and Postoperative Radiation With Novel Nomogram in Predicting Survival in the United States.

Background: There is controversy and limited data the management of rectosigmoid junction cancer (RSJC), especially the role of radiation. We aim to investigate the role of preoperative and postoperative radiation in RSJC and whether this cancer should be treated as a colon cancer or as a rectal cancer.

Methods: The data were extracted from the Surveillance, Epidemiology, and End Results (SEER) database and identified from 2000 to 2018.

Results: Of the 50,779 patients, 87% were ≥50 years old, 56.2% were male, 80.8% were White. Regarding tumor characteristics, 76% were Grade II, while 22.7% had distant-stage. 16.4% of patients were treated with multimodal therapy (surgery with chemoradiation), 47.9% surgery alone, 6.5% of patients received preoperative radiation, and 9.9% received postoperative radiation. Regarding prognostic significance of pre-operative and postoperative radiation factors, we evaluated factors, such as age, gender, race, tumor size, histologic variants of adenocarcinoma, and tumor grade. Patients with distant-staged tumors who received preoperative radiation had lower mortality compared to those who received postoperative radiation (95% CI, 0.73 - 0.97, (hazard ratio (HR) = 0.85, p = 0.04). There were no survival differences for localized or regional disease regarding pre and postoperative radiation, or when sub-stratifying for any other significant demographic or tumor characteristics.

Conclusion: Surgery with adjuvant chemoradiation had the best prognosis for all demographic and tumor characteristics. Preoperative radiation had a good prognosis only in distant disease. However, further randomized evidence is required to demonstrate the efficacy of pre-and post-operative radiation in rectosigmoid junction cancer.