Transverse colon cancer has a higher rate of major lymph node metastasis

Routine prophylactic extended lymphadenectomy to the superior mesenteric artery (SMA) may not be required for cecal and ascending colon cancer due to slower metastatic rates. In cases of transverse colon cancer, dissection around the SMA may be more necessary due to higher rates of metastasis to major lymph nodes, according to a study published in the journal 2019. Annals of Gastrointestinal Surgery.

Research has found that complete mesocolic excision (CME) can reduce the risk of colon cancer recurrence and help improve outcomes. CME includes central vascular litigation (CVL) as well as mesenteric resection and pericolonic lymph node dissection. Lymph node metastasis information is important for CVL, but the level of detail is low. The SMA and the superior mesenteric vein (SMV) are the two main areas for lymph node dissection. However, it is difficult to dissect the lymph nodes surrounding the right colon cancer with SMA.

This study aimed to evaluate the frequency and location of lymph node metastases and the short-term outcomes of lymphadenectomy surgery.

The study was conducted at 5 hospitals in Japan that perform lymphadenectomy. Patients were eligible if their tumors were located on the right side of the cecum, ascending colon, or transverse colon. If they have stage II or III disease, primarily lymph nodes around the SMA and SMV are available for dissection, and bowel resection more than 10 cm beyond the planned tumor will also be considered. History of chemotherapy or multiple cancers were exclusion criteria.

All patients underwent D3 lymphadenectomy for right-sided colon cancer. This was defined as removal of at least the major lymph nodes surrounding the aortic root of the tumor. Major lymph nodes were divided into lymph nodes surrounding SMA and lymph nodes surrounding SMV to evaluate the frequency of metastasis.

The primary endpoint was metastasis rate per lymph node station based on tumor location and major feeding arteries. Postoperative complications served as secondary endpoints.

A total of 208 patients were enrolled from April 2018 to August 2021, of which 25.0% tumors were located in the cecum, 54.8% in the ascending colon, and 20.2% in the transverse colon. The ileocolic artery (ICA) was the main artery, accounting for 62.5%, the right colic artery (RCA) accounted for 13.0%, and the middle colic artery (MCA) accounted for 24.5%. RCA was found during surgery in 37.5% of patients, and no pathological lymph node metastasis occurred in 60.6% of patients.

A total of 22.6% of patients underwent laparotomy and 77.4% underwent laparoscopic surgery, with right hemicolectomy (82.7%) being the most commonly performed procedure. Median (range) operative time was 213 (102-447) minutes, and median number of lymph nodes harvested was 38 (12-107).

Six patients (2.9%) with cecal cancer had major lymph node metastasis, and the major lymph node metastasis rate was 3.8%. 6 patients had metastasis. The mean (range) number of metastatic lymph nodes from major lymph nodes was 12 (5-32), all from pericolonic or intermedial lymph nodes.

Four of the patients had major lymph nodes located around the SMV, while 1 of the remaining 2 patients had metastases around the SMA, and the other patient had metastases around both the SMA and the SMV. After 189 cases of right hemicolectomy, one case each had metastasis in the pericolonic and middle lymph nodes, but no metastasis was found in the main lymph nodes.

Only 4.8% of patients with cecal cancer developed lymph node metastasis involving 2 of the ICA, RCA, and MCA. However, metastases were found in 39.6% of patients with ascending colon cancer and 30.8% of patients with transverse colon cancer. A total of 17% of tumors with ICA as the main blood supply artery developed lymph node metastasis, compared with 66.7% of tumors with RCA as the main blood supply artery and 41.2% of tumors with MCA as the main blood supply artery.

This study has several limitations. SMA or SMV and colon cancer subtypes involved fewer lymph node metastases. No lymph nodes from other regions were dissected except the mesentery. Preoperative imaging and intraoperative findings were not collected.

The researchers concluded that transverse colon cancer has higher metastatic rates than cecal and ascending colon cancer when dealing with major lymph nodes surrounding the SMV and SMA. Patients with transverse colon cancer or MCA aorta may require dissection around the SMA.

refer to

Tsukamoto S, Ouchi A, Komori K, et al. A multicenter prospective observational study of lymph node metastasis patterns and short-term outcomes of extended lymphadenectomy in right-sided colon cancer. gastrointestinal surgery. 2023;7:940-948. doi:10.1002/ags3.12703