Prognostic significance of lymph node yield after long‐course preoperative radiotherapy in patients with rectal cancer: a systematic review

Aim A literature review was performed to elucidate whether long‐course preoperative radiotherapy for patients with rectal cancer affects lymph node yield, and whether this influences prognosis. Method Cochrane Database, PubMed/MEDLINE, Scopus, Web of Knowledge, Embase and CINAHL databases and reference lists from published journal articles published between 1 January 1990 and 30 June 2011 were searched. Studies examining lymph node yield and prognosis were selected for review. Results One thousand and twenty‐nine articles were found, of which 11 met the inclusion criteria. None was a randomized controlled trial and all were cohort studies. Four studies showed that long‐course preoperative radiotherapy reduced lymph node yield; however only one demonstrated a statistically significant survival benefit in patients with higher lymph node yields. Five‐year survival was 48% in patients with fewer than and 69% in those with more than 11 lymph nodes identified in the operative specimen (P = 0.04). Conclusion Whilst long‐course preoperative radiotherapy appears to reduce lymph node yield in patients with rectal cancer, no causal relationship between lymph node yield and survival can be established in this group of patients.