Lymph node retrieval after preoperative chemoradiotherapy for rectal cancer

Area of Science:

• Oncology
• Surgical Pathology
• Cancer Research

Background:

• Current rectal cancer staging guidelines recommend retrieving at least 12 lymph nodes.
• Neoadjuvant chemoradiotherapy (nCRT) is increasingly used for rectal cancer but may impact lymph node yield.
• This study examines the effect of nCRT on lymph node retrieval in rectal cancer patients.

Purpose of the Study:

• To investigate the impact of neoadjuvant chemoradiotherapy on lymph node yield in rectal cancer.
• To determine if lymph node count after nCRT is a reliable indicator of oncologic adequacy.
• To assess the correlation between lymph node retrieval and patient survival outcomes.

Main Methods:

• Retrospective analysis of 162 rectal cancer patients undergoing curative surgery (2005-2010).
• Comparison of lymph node yield between patients receiving nCRT (n=71) and those not receiving nCRT.
• Multivariate analysis to identify factors affecting lymph node retrieval and survival.

Main Results:

• Neoadjuvant chemoradiotherapy was the sole independent factor reducing lymph node yield (14.2 vs. 19.4 nodes, P < 0.001).
• A higher percentage of patients receiving nCRT had fewer than 12 lymph nodes retrieved (29.6% vs. 9.9%, P = 0.003).
• Lymph node retrieval post-nCRT was inversely correlated with tumor regression grade; survival was similar regardless of node count.

Conclusions:

• Neoadjuvant chemoradiotherapy significantly decreases lymph node retrieval in rectal cancer surgery.
• Histopathologic response to chemoradiation influences the number of retrieved lymph nodes.
• Lymph node count should not be used as a surrogate for oncologic adequacy after nCRT for rectal cancer.