Lateral pelvic lymph node metastasis has a prognostic role in rectal cancer

This study investigated the prognostic role of extramural tumor deposits (clusters of cancer cells not attached to the main tumor) in the pelvic area in rectal cancer. Researchers suggested that tumor deposits near the pelvic lymph nodes was a useful predictor of prognosis.

Colorectal cancer is one of the most common cancers worldwide. Although, there have been rapid developments in diagnostic and treatment, a significant number of patients experience tumor recurrence (when the cancer comes back) and metastasis (spread to other parts of the body). Therefore, it is important to investigate ways to predict the outcomes of the cancer in order to improve the treatment plan.

Prior studies have reported that the incidence of lateral pelvice lymph node (LPLN) metastasis is 10-25% in rectal cancer patients. The presence of this type of metastasis is a poor prognostic factor. However, there is no information about the prognostic role of extramural tumor deposits (EX) in the LPLN area (LP-EX).

The objective of this study was to clarify the role of LP-EX in predicting rectal cancer outcomes. This study includes information about 172 patients with stage 2 and 3 rectal cancer who underwent rectal surgery and LPLN removal. The average follow-up period was 49.5 months. 

In 54 nodes found in 32 (18.6%) patients, LPLN metastasis (LP-LNM) was detected. 27 of these patients had only lymph node metastsis (LP-LNM group) while 14 also had extramural tumor deposits (LP-EX group).

The 5-year overall survival (time from treatment until death from any cause) was 61.1% for the LP-LNM group and 34.9% for the LP-EX group. The 5-year recurrence-free survival (time from treatment until disease recurrence) was 33.8% for the LP-LNM and 14.3% for the LP-EX. Moreover, distant metastases were more common in the LP-EX group than in the LP-LNM.

This study determined that LP-EX patients have worse prognosis, and that extramural tumor deposits are a useful predictor of outcomes in patients with rectal cancer that has spread to the pelvic lymph nodes.