Lymph node stations in the neck
Combined chemoradiotherapy is a standard therapy for the treatment of locally advanced squamous cell carcinoma of the head and neck (SCCHN) (webinar on both curative radiation and curative chemoradiotherapy to come within the next few months). Response rates are high, and cure rates surpass 50%, even for stage III and IV disease. Head and neck cancer tends to spread to the lymph nodes in the neck, and the neck is typically covered in the radiation field. Those patients with cancer remaining in the neck after chemoradiotherapy clearly need these nodes removed surgically to elicit a cure. But what about those who have a complete response, as judged by CT imaging? Are outcomes improved by elective lymph node dissection after successful chemoradiotherapy (as judged by CT) or is this just unnecessary surgery?
I think that the majority opinion right now leans towards neck dissection for most patients with N2 or N3 disease at presentation. Those who feel this way argue that neck dissection can improve local control and point to series showing that neck dissections find residual disease in about a quarter of patients. Older data showed advantages both in local control and disease-free survival for neck dissection and ASCO guidelines for larynx cancer endorse this perspective.
But have things changed with better chemoradiotherapy? In more modern series, the disease control advantage is less clear. Isolated neck recurrence has become rare in patients with complete response to chemoradiotherapy-it’s now under 5%. A JCO paper in 2006 showed a lack of survival advantage for elective lymph node dissection for patients with complete response on CT. Investigators at the University of Florida looked back at 550 patients with node positive SCCHN treated with radiation therapy (76%) or chemoradiotherapy (24%); 62% also had elective lymph node dissection. All patients had CT imaging a month after the completion of therapy. Of those patients who had neck dissection, the negative predictive value of being NED on CT imaging was 94%. Of 32 patients with radiographic complete response and no elective lymph node dissection, the five year neck-control rate was 100% and cause-specific survival was not different from patients with neck dissection. NCCN guidelines follow this perspective, listing active observation as a treatment option.
Why am I blogging about this now? A new study presented this week (6/4/10) at ASCO studied this question in a very large series from MD Anderson Cancer Center. They looked back at their experience over a decade from 1994 to 2004. During this period, the institutional policy was to not perform elective neck dissection for patients with a complete nodal response to irradiation. They looked back at 935 patients and found that half had a complete nodal response in the neck as judged by CT. The key finding was that among patients with complete nodal response and no elective neck dissection, there was only a 4% incidence of neck-only recurrence. This suggests that those patients with complete nodal response on CT from chemoradiotherapy can safely forgo elective neck dissection. One subgroup was notable-hypopharynx patients with big nodes at presentation had high failure rates, even when they had a complete nodal response, suggesting that this group may benefit from additional therapy, such as elective nodal dissection. One final finding was of note from this study, and it is consistent with previous literature. Among patients who did have a nodal dissection, prognosis was better when there was a pathologic complete response (no residual living cancer cells in the nodes taken out). This makes common sense-if the main therapy kills all your cancer cells, you do better! What’s harder is to know what to do with those patients with residual cancer on elective node dissection. Should they be given additional therapy to try to improve their cure rates? Or, has their cancer demonstrated that it is not sensitive to our therapies, meaning that this extra therapy would only cause toxicity without added cancer control?