A0092 - Pattern of Distant Organ Metastasis and Effects on Survival in Rectal Adenocarcinoma: A Population-Based Study

Diana Franco, MD¹, Mohammad Rehman, MBBS², Faizan Fazal, MBBS², Saad Tahir, MBBS², Jawad Basit, MBBS², Sajeel Saeed, MBBS^2
1Loyola Medicine/MacNeal Hospital, Berwyn, IL; ²Rawalpindi Medical University, Rawalpindi, Punjab, Pakistan

Introduction: Metastasis to distant organs is associated with a poorer prognosis in patients with rectal adenocarcinoma (RAC). Identification of risk factors for metastasis is crucial for early detection. We used the Surveillance, Epidemiology and End-Results (SEER) database to determine the frequency, risk factors, and prognosis of metastasis in RAC patients.

Methods: Data on sociodemographic and tumor characteristics of RAC patients from 2010 to 2018 were retrieved from the SEER database. Patients with a histologically confirmed diagnosis of RAC were included. Patients diagnosed at autopsy and those with incomplete survival data were excluded. Overall survival (OS) was defined as the time from diagnosis to death from any cause or end of follow-up. Cancer-specific survival (CSS) was defined as the time from diagnosis to death due to rectal adenocarcinoma or end of follow-up. Descriptive statistics, multivariate logistic regression, and Cox regression were applied using SPSS version 25. Kaplan Meier survival curves were constructed.

Results: We included 13,564 patients with RAC. Metastasis to any site, liver, lung, bone, and brain, was reported in 11.5%, 9.6%, 4.1%, 0.8%, and 0.1% of patients, respectively. Sociodemographic and tumor characteristics of patients with and without metastasis are reported in Table 1. On logistic regression, significant risk factors for metastasis were age< 50 years (adjusted odds ratio (aOR) 1.168), grade 4 (aOR 2.119), T4 (aOR 1.866), N2 (aOR 4.520), and patients without surgery (aOR 9.71). The median OS and CSS in metastatic RAC were 24 and 25 months, respectively. Median OS of one, two, and three metastatic sites were 27, 15, and 8 months, respectively (P< 0.001) (Figure. 1). On Cox regression, variables significantly associated with decreased OS were age greater than 75 years (adjusted hazard ratio (aHR) 2.13), grade 4 (aHR 1.436), T4 (aHR 1.31), N2 (aHR 1.257), and tumors >200mm (aHR 1.229). Variables significantly associated with decreased CSS were age greater than 75 years (aHR 2.009), grade 4 (aHR 1.487), T4 (aHR 1.278), N2 (1.304), and tumors >200 mm (aHR 1.259).

Discussion: Metastasis was reported in 11.5% of patients, most commonly in the liver (9.6%). The site-specific risk factors for metastasis reported in our study may facilitate the identification of high-risk groups that need careful surveillance.




Disclosures:


Diana Franco, MD¹, Mohammad Rehman, MBBS², Faizan Fazal, MBBS², Saad Tahir, MBBS², Jawad Basit, MBBS², Sajeel Saeed, MBBS². A0092 - Pattern of Distant Organ Metastasis and Effects on Survival in Rectal Adenocarcinoma: A Population-Based Study, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.