Lymph node-positive head and neck cancer treated with definitive radiotherapy: can treatment response determine the extent of neck dissection?

BACKGROUND: The purpose was to determine if postradiotherapy (RT) neck dissection can be limited to the neck levels of residual adenopathy on post-RT computed tomography (CT).
METHODS: In all, 274 patients with lymph node-positive head and neck squamous cell carcinoma were treated with definitive RT. All patients had a contrast-enhanced CT performed 4 weeks after completing RT to evaluate tumor response. Two hundred eleven heminecks were dissected, either planned pre-RT or because of residual adenopathy on post-RT CT. CT images were reviewed to determine the presence and location of residual adenopathy. Radiographic complete response (rCR) was defined as lymph node size < or =1.5 cm and normal radiographic morphology (no filling defects or calcifications). For each neck level the CT findings were correlated with neck dissection pathology.
RESULTS: Correlation of CT nodal response with neck dissection pathology revealed the following negative predictive values of rCR: level I, 100%; level II, 95%; level III, 98%; level IV, 96%; and level V, 96%. A subset analysis was performed on 61 neck levels with initially positive lymph nodes that completely responded to RT that were in a hemineck with residual lymphadenopathy elsewhere in the neck. Correlation of nodal response on CT to pathology indicated a negative predictive value of an rCR of 95% for this high-risk scenario. In 71 heminecks that underwent a selective neck dissection (defined as dissection of less than levels I-V) the 5-year neck control rate was 100%.
CONCLUSIONS: rCR on post-RT CT has a negative predictive value of > or =95% for each neck level. This suggests that limiting neck dissection based on post-RT CT is safe.