A distinct form of colorectal cancer: signet ring cell carcinoma

Colorectal signet ring cell carcinoma (SRCC) is a rare histological subtype of colorectal cancer (CRC), accounting for about 1% of all cases. Due to its rarity, many pathological aspects of SRCC have not been fully clarified. This study set out to characterize the clinicopathology of SRCC and to create a superior nomogram, ultimately to inform treatment selection and prognosis with new evidence.

The patients for our research were collected from the Surveillance, Epidemiology, and End Results (SEER) database. χ² tests were used to compare data significance. The best cut-off value was determined by X-tile software. The Kaplan-Meier method with log-rank test served to compare survival among groups. The Cox proportional hazard regression model functioned to analyze prognostic factors for survival. Univariate and multivariate analyses were utilized to filtered out the independent risk factors. The nomogram model was developed a by R software.

A total of 49,405 patients were included, with 842 SRCC patients (1.7%) and 48,563 colorectal adenocarcinoma (COAD) patients (98.3%). In SRCC, patients were of younger age, more poorly differentiated tumor grade (62.71% vs. 14.12%), more advanced American Joint Committee on Cancer (AJCC) stage (37.88% vs. 31.35% in III; 45.25% vs. 25.94% in IV), more common in the right colon (56.89% vs. 32.12%), and more bone and distant lymph node metastasis (3.3% vs. 3.1%, P=0.002; 63.7% vs. 47.6%, P<0.001, respectively) than patients with COAD. SRCC patients had shorter median survival time than COAD patients (17 vs. 59 months) and lower 1-, 3-, and 5-year survival rates (83.49% vs. 57.83%; 63.53% vs. 30.99%; 46.9% vs. 5.9%). Comprehensive treatment including surgery, chemotherapy and radiotherapy was still the best treatment of SRCC patients. By incorporating absorbed lymph node positive rate (LNR) grouping and treatment strategy, we developed a more advantageous nomogram model.

SRCC is a distinct entity, and its unique clinicopathological features should be considered more in the diagnosis and treatment process. With LNR and treatment strategy taken into account, the nomogram model had better predictive ability and stability.