HDR Interstitial Brachytherapy in the Management of Lip Malignancies

Abstract

Brachytherapy is an appealing alternative to external beam radiotherapy in the management of early stage primary lip cancers. Historically LDR brachytherapy and recent HDR brachytherapy has been shown to provide at least equivalent local control and improvement in the therapeutic ratio compared to external beam radiation. We report our department experience over the last 3 years. Since 2013, HDR interstitial brachytherapy has been offered to patients with squamous cell carcinoma involving the non-hair bearing lip. It has been offered as monotherapy in the definitive setting for early stage lesions as well as adjuvant therapy in post-operative patients with known pathologic risk factors (+ margins, + PNI) or as a boost after external beam radiotherapy in locally advanced patients requiring nodal irradiation. Since April 2013 through December 2016, 17 patients with Tis-T2 N0 M0 SCCA have been treated with interstitial brachytherapy. 14 patient patients were treated with definitive radiotherapy. 10 of those patients received brachytherapy has monotherapy, while 4 others received external beam radiotherapy followed by a brachytherapy boost. 1 patient received brachytherapy for a recurrence after prior external beam radiation and surgical salvage for recurrence. 2 patients received it as adjuvant therapy after primary surgical resection for known pathologic risk factor of PNI. Brachytherapy dose was 42.5-47.5 Gy in 10 fractions given BID over 1 week in the setting of definitive monotherapy, 17-24 Gy in 5-6 fractions given BID in the setting of a boost after external beam radiation and 35-36 Gy in 9-10 fractions given BID over 1 week in the setting of post-surgical adjuvant therapy for microscopic disease. The median time to follow-up for this cohort is 18 months (3-38 months). The local control rate is 94.1%. There has been one local failure which was then salvaged with single agent Cetuximab. There has been one regional failure along the path of ipsilateral CN V3 which was then treated with chemoradiation. There have been no nodal failures. HDR Interstitial brachytherapy is an excellent radiotherapeutic option for early stage lip SCCA. It offers a very convenient alternative to patients with early stage disease allowing their treatment time to be condensed to 1 week in lieu of a 6-7 week course of external beam radiation.