Effects of Tumor Localization, Age, and Stage on the Outcomes of Gastric and Colorectal Signet Ring Cell Adenocarcinomas

SIMPLE SUMMARY: Signet ring cell adenocarcinomas are an extremely rare type of cancer that arise primarily in the stomach and colon. These cancers tend to present at an earlier age with more advanced disease. It is, however, not known if disease progression depends on the location within the stomach or the colon from where it arises. Across both sexes and all ages, these cancers occur more often in the distal rather than the proximal stomach, compared to regular gastric cancers. For early disease stages, younger patients have similar outcomes to regular gastric cancers, but there are worse outcomes in older patients. In colorectal cancer patients with signet ring cells, outcomes are worse universally across all ages and stages, and most of these cancers arise in the right colon. Mortality, however, is worse in cancers arising from the left colon and rectum. This work offers insights into factors that better characterize their pathology. ABSTRACT: Signet ring cell adenocarcinomas (SRCCs) are a rare histological adenocarcinoma subtype, classically thought to have a worse prognosis than conventional adenocarcinomas. The majority of these cancers occur in the stomach, colon, and rectum. Their rarity means that most epidemiological studies into their pathology are often underpowered, and interpretations from these reports are mixed. In this study, we use the Surveillance, Epidemiology, and End Results Program (SEER) database to examine the effects of tumor localization, age, and stage on gastric and colorectal cancer outcomes. For early onset localized and regional gastric cancers, SRCCs have the same overall risk of mortality compared to conventional adenocarcinomas. Over the age of 50 years, SRCCs have worse outcomes across all stages. Gastric SRCCs are 2–3-fold more likely in younger patients, and more heavily favor the distal stomach. Like conventional adenocarcinomas, proximal gastric SRCCs have decreased survival. Across all ages, stages, and locations, colorectal SRCCs have worse outcomes. SRCCs favor the right colon, but outcomes are significantly worse for the left colon and rectal cancers. Relative to adenocarcinomas, colorectal SRCCs have the worst outcomes in younger patients. Overall, these results provide insights into SRCC disease patterns that cannot be surmised outside of population-level data.