Less than 12 nodes in the surgical specimen after total mesorectal excision following neoadjuvant chemoradiation: it means more than you think!

BACKGROUND: A minimum of 12 examined lymph nodes (LN) is recommended to ensure adequate staging and oncologic resection of patients undergoing proctectomy for rectal adenocarcinoma. However, a decreased number of LN is not unusual in patients receiving neoadjuvant chemoradiation.
PURPOSE: We hypothesized that a decreased number of LN in the proctectomy specimen of these patients may be an indicator of tumor response and be associated with improved prognosis.
METHODS: A single-center colorectal cancer database was queried for c-stage II-III rectal cancer patients undergoing neoadjuvant chemoradiation followed by proctectomy between 1997 and 2007. Patients were categorized into two groups according to the number of LN retrieved from the proctectomy specimen: <12 LN versus ≥12 LN. Groups were compared with respect to demographics, tumor and treatment characteristics, and the following oncologic outcomes: overall-survival (OS), cancer-specific-mortality (CSM), cancer-free-survival (CFS), distant (DR), and local recurrences (LR).
RESULTS: The query returned 237 patients. There were 173 (73 %) males, and the median age was 57 years [interquartile range (IQR) 49-66 years]. The median number of LN retrieved was 15 (IQR 10-23) and 70 (30 %) patients had less than 12 nodes examined. The <12 nodes group was older [60 (IQR 51-71 years) vs. 55 (IQR 48-65 years), p = 0.009] and had more pathologic complete responders (36 vs. 19 %, p = 0.01). No <12 nodes patient experienced a LR, whereas the 5-year LR rate was 11 % in the ≥12 nodes group (p = 0.004). Other oncologic outcomes were not significantly different.
CONCLUSIONS: Retrieval of less than 12 nodes in the proctectomy specimen of rectal cancer patients treated with neoadjuvant chemoradiation does not affect OS, CSM, CFS, or DR and may be a marker of higher tumor response and, consequently, decreased LR rate.