PURPOSE
Study clinical characteristics of Rectal Mucinous Adenocarcinoma (RMA).
BACKGROUND
RMA is a rare histological subtype with an impaired response to chemoradiotherapy and an overall poor prognosis. High-grade tumors are associated with older age. Previous studies have shown conflicting results on prognosis.
METHODS
Retrospective analysis of National Cancer Database was conducted from 2004-2020 for subjects with histology code 8480 in primary sites C19 and C20 (rectosigmoid-junction and rectum, n = 14,044), using multivariate analysis with Cox regression.
RESULTS
Median age of diagnosis was 65 years with 69.5% were in the 45-75 years age range. 59.2% were male while 40.8% were female. 84.7% were White, 9.7% were Black, 0.4% were American Indian and 3.4% were Asian. 6.9% were Hispanic. 33.9% were in the upper-income quartile. 40.6% were seen at community cancer programs while 33% went to academic programs. 36.5% had stage III RMA. Out of the 14,044 patients with RMA, 10,546 received surgery, 5,179 received chemotherapy, 233 received immunotherapy and 55 received hormone therapy. Patients >75 years had significantly lower overall survival (OS) compared to those <45 years (HR 0.67). Female patients had significantly higher OS than male (HR - 0.07). Black patients had significantly lower OS than White (HR 0.08). Hispanic patients had significantly higher OS than non- Hispanic (HR - 0.14). Patients with private and government insurance had significantly higher OS than noninsured patients (HR - 0.35 and - 0.26 respectively). Patients with median higher-income quartiles had significantly higher OS than lower quartiles (HR - 0.13). Academic facilities had significantly higher OS than community programs (HR - 0.13). Patients who received surgery had significantly higher OS than those that did not (HR - 0.67); median survival for patients who received surgery was 71 months vs 28 months for non-surgical candidates.
CONCLUSIONS
Surgery is the most important treatment modality in RMA. Uninsured, older Black male patients from lower-income quartiles had significantly lower OS. Access to academic centers also contributed to differences in OS outcomes which throws light on healthcare disparities.
IMPLICATIONS
Additional studies need to be conducted for viable solutions to assist with social determinants of healthcare in RMA.