Clinicopathological Features and Prognostic Impact of Colorectal Signet-Ring Cell Carcinoma: The Prognostic Impact of Metastatic Lymph Node Histology.

Objectives: Colorectal signet-ring cell carcinoma (SRCC) is a rare histological subtype, accounting for only 0.2-0.9% of all colorectal cancers, and is often diagnosed at an advanced stage with a poor prognosis. However, the clinicopathological and prognostic characteristics of colorectal cancers with SRCC components remain poorly defined. Methods: We retrospectively analyzed 35 patients who underwent surgical resection for primary colorectal cancer containing SRCC components between September 2002 and December 2022 at the Shizuoka Cancer Center. The patients were divided into two groups according to the predominant histological subtype: SRCC (n = 7) and adenocarcinoma with a signet-ring cell component (AC with SRC; n = 28). Clinicopathological features and survival outcomes were compared between the groups. Among the patients with lymph node metastasis, survival was compared according to the presence of SRCC in the metastatic lymph nodes (LNM SRCC+, n = 13; LNM SRCC-, n = 13). Results: Of the 35 patients, 7 were classified as having SRCC and 28 as having AC with SRC. Most cases were T3 or deeper tumors (85.7%), with frequent lymphatic invasion (82.9%) and lymph node metastasis (74.3%). The prognosis did not differ between SRCC and AC with SRC, whereas the presence of SRCC in metastatic lymph nodes was associated with significantly poorer overall and relapse-free survival (P = 0.048 and 0.012, respectively). Conclusions: Colorectal cancers with SRCC components are typically advanced and aggressive. The presence of SRCC components confers a poor prognosis, and SRCC in metastatic lymph nodes represents an important adverse prognostic indicator.