Impact of neoadjuvant therapy on the lymph node yield after surgery for rectal cancer.

INTRODUCTION : The number of lymph nodes harvested from the surgical specimen after total mesorectal excision (TME) is a key factor in the contemporary management of rectal cancer. In 1931, Ernest Miles identified the upward zone of lymphatic spread of rectal cancer along the superior haemorrhoidal vessels and the inferior mesenteric vein as being the most constant and therefore the most important route of rectal cancer spread. Subsequently, Grinnell2 and Dukes reported that both the number of lymph node metastases and their location affects the prognosis in patients with rectal cancer. The number of lymph nodes retrieved indirectly reflects the quality of both surgical and pathologic procedures. In 1990, the Working Party Report to the World Congress of Gastroenterology in Sydney suggested that a minimum of 12 lymph nodes should be recovered for colorectal cancer staging. This was adopted in 1999 by the American Joint Committee on Cancer. The examination of fewer than 12 LNs is considered a surrogate marker of inadequate surgery and/or pathologic examination and is a relative indication for adjuvant therapy. Removal of fewer lymph nodes is also associated with a poorer survival and higher rates of local recurrence. If the nodal status is not determined accurately, the prognosis may be difficult to determine and it may be incorrect. Many factors influence the number of lymph nodes retrieved. These factors may be related to the patient (sex, obesity), to the surgeon (specimen size and type of lymphadenectomy) to the tumour (size, stage, and localization) and to the pathologist (experience and technique used for harvesting the specimen). AIMS AND OBJECTIVES : 1. To evaluate the influence of neoadjuvant therapy on lymph nodal yield. 2. To evaluate the various factors influencing the lymph nodal yield after neoadjuvant therapy 3. To evaluate the impact of nodal yield following neoadjuvant therapy on survival. MATERIALS AND METHODS : A retrospective analysis of 331 patients who underwent curative resection for rectal cancer in the Department of Surgical Oncology, Cancer Institute (WIA), Chennai between January 1, 1991, and December 31, 2005 was done. Basic demographics, tumour location, type of surgery and postoperative staging were retrospectively recorded. The rectum was defined as follows: low rectum (0 to 5 cm from the anal verge), mid rectum (5 to 10 cm), and high rectum (10 to 15 cm). 225 patients received NCRT during the study period. 106 patients underwent straight surgery. NCRT was administered in patients with clinical stage of cT3/cT4 or cN+ disease. Diagnosis was based on the findings clinical examination, endoscopy and computed tomographic scans. CONCLUSION : 1. Patients with rectal cancer undergoing NCRT had a reduced nodal yield after surgery. 2. The factors co‐related with nodal yield were age and type of neoadjuvant therapy. 3. The cut‐off of 12 nodes had no prognostic significance after NCRT. 4. Patients in whom no nodes were harvested had survival better than patients in whom nodes were harvested. 5. For node negative patients harvest of 6 nodes for early pT0 to pT2 tumours had prognostic significance