Significance of retropharyngeal lymph node dissection in hypopharyngeal cancer.

OBJECTIVE We investigated the risk factors for metastasis to retropharyngeal lymph nodes (RPLNs) and the significance of dissection of RPLNs in hypopharyngeal cancer. Metastasis to the RPLNs is an important prognostic factor in head and neck cancer, especially in hypopharyngeal cancer. METHODS Study subjects were 129 cases who received primary treatment at nine leading medical facilities in the field of head and neck cancer management in Japan. Focusing on RPLNs, we compared prognosis in RPLN-metastasis-positive, RPLN-metastasis-negative, RPLN-dissected and RPLN-non-dissected cases. RESULTS The 5-year survival rate for the entire study group was 41.1%. Metastasis to RPLNs occurred during the follow-up period in 13.2%. RPLN dissection was performed in 32 of the 129 cases at the time of primary treatment. In the RPLN-dissected group, the 5-year survival rate in the RPLN-metastasis-positive subgroup was 30.0%, whereas that in the RPLN-metastasis-negative subgroup was 41.2%, showing no statistically significant difference. Among 17 cases having RPLN metastasis, 30.0% in the RPLN-dissected group (n = 10) survived for 5 years versus none in the RPLN-non-dissected group (n = 7). The rate of RPLN metastasis was higher in primary hypopharyngeal cancer of the posterior wall/post-cricoid area (PC/PW) compared with that of the piriform sinus (P = 0.020). CONCLUSIONS We recommend RPLN dissection at the time primary of treatment of hypopharyngeal cancer, especially in cases with cancer at subsites PC/PW, as RPLN dissection is expected to improve prognosis. The primary subsites PC/PW are associated with a risk of RPLN metastasis.