Background: The yield of lymph nodes (LN) in abdominoperineal resection (APR) specimen is notoriously low, which may be related to preoperative radiation therapy (XRT). This has important implications for tumor staging, especially in patients with squamous cell carcinoma of the anus (SCCA), who are commonly treated with a higher dose (60-70 Gy) than patients with rectal cancer (45-50 Gy). We hypothesized; 1) that the yield of LN retrieval in APR specimen was radiation dose-dependant and 2) that LN retrieval was consequently inferior in patients with SCCA by comparison with patients with rectal cancer.
Methods: We performed a retrospective study on 102 patients who underwent APR in a single institution between 1980 and 2004. Pathological reports were reviewed and the number of lymph nodes retrieved in APR specimens was correlated with: 1) Location (anal or rectal) of cancer; 2) Dose of pelvic irradiation; 3) Time interval between the end of XRT and surgery. Results: There were 61 men and 41 women, with a median age of 66 (range 25-89) years. There were 12 patients operated for SCCA and 90 for rectal cancer. 83% and 46% of patients with anal and rectal cancer respectively underwent neoadjuvant radiotherapy. The mean±SD number of LN in APR specimen was 9.2±5.9. The mean number of LN in APR specimen was significantly lower in patients who underwent preoperative XRT (8±5.5 vs. 10.5±6.1, Mann-Whitney test p=0.02). The mean number of LN was also lower in patients with SCCA than in patients with rectal cancer (6.2±5.3 Vs. 11.5±5.9, t test p=0.01). Finally, there was a inverse correlation between the yield of LN and the time elapsed between XRT and surgery (linear regression coefficient r=-0.32, p=0.03). Conclusion: Our data indicate that: 1) radiation therapy affects the yield of LN retrieval in APR specimen; 2) this impact is dose- and time-dependent. These findings have important implications as regard to postoperative staging of anal and rectal cancers and subsequent decision-making regarding adjuvant chemotherapy.
500 Cummings Center
+1 978-927-8330
+1 978-524-0498
