Pathologic complete response implies a fewer number of lymph nodes in specimen of rectal cancer patients treated by neoadjuvant therapy and total mesorectal excision

Abstract

Studies have suggested that the use of neoadjuvant chemoradiation results in a lower lymph nodes yield in rectal cancer patients. Objective: To evaluate factors associated with less than 12 lymph nodes harvested on patients with rectal cancer treated with preoperative chemoradiotherapy followed by total mesorectal excision. Patients: This was a cohort/retrospective single cancer center study. Low and mid locally advanced rectal cancer or T2N0 under risk of sphincter resection underwent chemoradiotherapy followed by total mesorectal excision with curative intent. Chemotherapy consisted of 5-FU and leucovorin IV. Total dose of pelvic radiation was 5040 Gys. All patients were staged and restaged by digital rectal examination, proctoscopy, colonoscopy, CT of abdomen and chest, and MRI of the pelvis. Patients were stratified in two groups: ≥12 and < 12 L N retrieved. The possible factors affecting number of LN were analyzed. Results: 95 patients met the inclusion criteria. Mean LN harvest was 23.2 (3–67). 81 patients (85%) had ≥12 L N. Gender, age, tumor size, tumor stage, tumor location, length of specimen, presence of LN involvement, type of surgery, and surgical access showed no association with number of LN retrieved. Only pathological complete response showed a statistically significant association with <12 L N on univariate (p = 0.004) and multivariate analyses (p = 0.002). Limitations: Data were collected retrospectively. The number of patients disparity between the two groups. Conclusions: Complete pathologic response is associated with <12 L N harvested. Thus, the number of lymph nodes should not be used as a surrogate for oncologic adequacy of resection in patients with pathologic complete response.