Patterns of Distant Organ Metastasis and Risk Factors in Rectal Adenocarcinoma Patients: A Retrospective Cohort Analysis.

Background In this study, we aimed to analyze the metastatic patterns of rectal adenocarcinoma (RAC) to specific organs, assessing the incidence, associated risk factors, and prognostic implications of metastasis. Methodology We conducted a retrospective cohort study utilizing data from the Surveillance, Epidemiology, and End Results database, focusing on RAC patients diagnosed between 2010 and 2018. Analyses were performed to evaluate overall survival (OS) and cancer-specific survival (CSS). Results We included 13,564 patients with RAC. Significant risk factors for metastasis were age <50 years (odds ratio (OR) = 1.168), grade 4 (OR = 2.119), T4 (OR = 1.866), N2 (OR = 4.520), and patients without surgery (OR = 9.71). The median OS and CSS in metastatic RAC were 24 and 25 months, respectively. Variables significantly associated with decreased OS were old age, high-grade tumors, T4, N2, tumors >200 mm, no surgery, and multiple metastatic sites. The variables significantly associated with reduced CSS were old age, high-grade tumors, T4, N2, tumors larger than 200 mm, no surgery, and multiple metastatic sites. Conclusions The liver was the most common organ in which metastasis occurred. Significant risk factors observed in RAC patients for metastasis were age <50 years, grade 4, T4, N2, and patients without surgery. Old age, multiple metastatic sites, high-grade tumors, T4, N2, tumors larger than 200 mm, and no surgery were strongly linked to a lower OS rate.