Failure patterns of head and neck squamous cell carcinoma treated with radical radiotherapy by intensity modulated radiotherapy technique using focal volume and dosimetric method

Labeling locoregional failures in head and neck cancer (HNC) as "local" and "regional" becomes incomplete when treating with intensity modulated radiotherapy (IMRT). Target delineation and delivery errors, dose in-homogeneity complicate the assessment of failures. A combination of focal point and dosimetric method might attempt at simplifying failure analysis.

One hundred eleven patients with locally advanced HNC treated with chemoradiation using IMRT were enrolled. Patients with documented failure had their recurrence volume assessed using focal point and dosimetric method.

With a median follow-up of 20 (range 0-39) months and median locoregional control (LRC) of 30 (range 24.8-34.5) months, the patients had a 3-year overall survival and LRC of 70.6% and 48.9%, respectively. Of 39 failures, there were 69.2%, 7.6%, 5.1%, 12.8%, and 5.1% type A, B, C, D, and E, respectively using the focal point and dosimetric method.

With the current classification, majority of the recurrences were high dose failures suggesting inherent radioresistance. While minority of failures were potentially preventable and needed modifying existing IMRT workflow.