Metastatic cutaneous squamous cell carcinoma to parotid nodes: the role of bolus with adjuvant radiotherapy.

INTRODUCTION

Information regarding the addition of tissue equivalent bolus to adjuvant radiotherapy (RT) for intra-parotid metastatic head and neck cutaneous squamous cell carcinoma is lacking. This study aimed to evaluate the effect of bolus versus no bolus on the patterns of regional and distant recurrence, regional control (RC), cancer-specific survival (CSS), overall survival, RT toxicity and RT interruption.

METHODS

A retrospective study was performed on consecutive patients diagnosed between 1994 and 2008 with metastatic head and neck cutaneous squamous cell carcinoma who were treated with parotidectomy ± selective neck dissection and adjuvant RT ± parotid bolus.

RESULTS

Seventy-five patients were identified: 64 males and 11 females, with median age of 79 years (range 40-96) of which 39 had bolus during RT. Median follow up was 48 months (range 4-177). There were 23 regional recurrences - 14 dermal, six dermal + nodal and three isolated nodal - and only two systemic recurrences. Nine patients had RT interruption >6 days due to acute skin toxicity. Bolus was associated with increased grade ≥3 radiation dermatitis (P = 0.02). RT interruption >6 days was significantly associated with inferior RC and hazard ratio, 2.83 (95% confidence interval: 1.04-7.71, P = 0.042). Lympho-vascular space invasion, positive margins and nodes >2 cm were adversely significant on CSS multivariate analysis. RC, CSS and overall survival at 5 years were 67, 66 and 52%, respectively.

CONCLUSIONS

Dermal involvement dominated the pattern of regional recurrence. Bolus was associated with significantly worse skin reaction. Bolus use was not associated with a significant overall benefit on RC. This analysis does not support the use of bolus as applied in this cohort.