Response assessment by combined PET-CT scan versus CT scan alone using RECIST in patients with locally advanced head and neck cancer treated with chemoradiotherapy.

PURPOSE

RECIST have limitations when applied to potentially curable locally advanced squamous cell carcinoma of the head and neck (SCCHN). [¹⁸F]fluorodeoxyglucose-positron emission tomography (PET) scan may be useful in assessing treatment response and predicting patient outcome.

PATIENTS AND METHODS

We studied patients with previously untreated stages III-IVb SCCHN treated with primary concurrent chemoradiotherapy on five prospective clinical trials. Response was assessed by clinical exam, computed tomography (CT), and PET portions of combined PET-CT scan ∼8 weeks after completion of chemoradiotherapy.

RESULTS

Fifty-three patients were analyzed. Complete response (CR) was demonstrated in 42 patients (79%) by clinical exam, 15 (28%) by CT, and 27 (51%) by PET. CR as assessed by PET, but not as assessed by clinical exam or CT using RECIST, correlated significantly with progression-free status (PFS) (P < 0.0001). The 2-year PFS for patients with CR and without CR by PET was 93% and 48%, respectively (P = 0.0002).

CONCLUSIONS

A negative PET scan on combined PET-CT after chemoradiotherapy is a powerful predictor of outcome in patients receiving curative chemoradiotherapy for SCCHN. PET-CT is indicated for response evaluation in this setting to improve the accuracy of post-treatment assessment by CT.