Lateral pelvic recurrence: do numbers matter?

This study pinpointed factors that can predict cancer recurrence in the pelvis in patients treated with chemoradiotherapy before surgery.

In locally advanced rectal cancer the cancer has grown from the rectum (the lowest part of the large bowel) into surrounding tissues and organs, or has spread beyond the bowel. The standard treatment is a combination of surgery and medication. The most common surgical approach is to remove the tumor along with a significant length of bowel around the tumor (total mesorectal excision). Chemotherapy and radiotherapy (chemoradiotherapy) are also given before surgery to decrease the chance of the tumor returning.

Unfortunately, some patients will experience return of the cancer even after this treatment. One common location for the cancer to return is in the surrounding pelvis (lateral pelvic recurrence; LPR). Patients with LPR have poorer quality of life and increased risk of mortality (death). Therefore, pinpointing risk factors that can predict recurrence would benefit patient care. Previous research has suggested that examining the lateral pelvic lymph nodes (lymph nodes in the area surrounding the rectum) could help predict LPR.

443 patients with locally advanced rectal cancer who received chemoradiotherapy before surgery were included in the study. Cancer returned in 24.2% of patients during the 52 month follow-up. For 12% of patients the cancer returned close to the original rectal location. Over 50% of those patients developed LPR.

Statistical analysis showed that the number of affected lateral pelvic lymph nodes and the ratio of lymph nodes testing positive for cancer compared to  the total number tested were linked to the chance of experiencing LPR. Increased numbers of lateral pelvic lymph nodes increased the odds of LPR by 70%. The ratio lateral pelvic lymph nodes with cancer versus no cancer also increased the odds of LPR by 70%.

The authors concluded that the ratio of cancerous lymph nodes and the number of lymph nodes could be linked to LPR and poor survival in the patients. They suggest that analyzing these lymph nodes could help predict patient outcome.