Patterns of lymph node metastasis and long-term outcomes of splenic flexure colon cancer: a descriptive study from a Japanese high-volume center.

PURPOSE

The pattern of lymph node metastasis and the appropriate extent of lymph node dissection in splenic flexure colon cancer remain unclear. This study aimed to describe the clinical characteristics, lymph node metastasis patterns, and oncological outcomes of patients with splenic flexure colon cancer.

METHODS

The data of patients with splenic flexure cancer diagnosed with pathological stages I-III were extracted from a hospital database. Lymph nodes were mapped and numbered according to the guidelines of the Japanese Society for Cancer of the Colon and Rectum. Five-year disease-free survival (DFS) and overall survival (OS) rates were estimated using the Kaplan-Meier method.

RESULTS

Among 151 patients, 37.1% had lymph node metastasis. The proportion of lymph node metastasis were 30.1% at station 221, 5.1% at station 222, 2.8% at station 223, 19.8% at station 231, 2.7% at station 232, and 0% at station 253. Among the 59 patients with an accessory middle colic artery, 19 had lymph node metastasis only at stations 221 (14/47) and 231 (5/47). The 5-year estimated DFS rates were 100% for stage I, 94.4% (95% CI, 83.6-98.2) for stage II, and 79.9% (95% CI, 65.6-88.8) for stage III. Ten patients experienced distant recurrence: liver (n = 5), peritoneum (n = 2), para-aortic lymph node (n = 2), and lung metastasis (n = 1). No local recurrence was observed.

CONCLUSION

In splenic flexure colon cancer, lymph node dissection around the IMA route may be omitted. Similarly, dissection along the left branch of the middle colic artery or the left colic artery may be unnecessary in the presence of an accessory middle colic artery.