Intraoperative high-dose-rate brachytherapy for paranasal sinus tumors

Advanced and recurrent tumors of the paranasal sinuses can be difficult to irradiate to high doses with standard external beam radiotherapy (EBRT), conventional brachytherapy, or intraoperative electron beams. We, therefore, explored the role of intraoperative high-dose-rate brachytherapy (IOHDR) as a boost to EBRT in primary tumors or as sole adjuvant treatment in recurrent disease.

Between 1992 and 1998, 34 patients with locally advanced tumors arising in the paranasal sinuses were treated with IOHDR after maximal surgical excision. Twenty-seven patients with new primaries underwent gross resection and 10-12.5 Gy IOHDR followed by 45-50 Gy EBRT. Seven previously irradiated (45-63 Gy) patients with recurrent disease were treated with 15-20 Gy of IOHDR alone after gross excision. Local control and overall survival were analyzed using the Kaplan-Meier method and compared using the log-rank test.

After a mean follow-up of 6 years (range 34-120 months), the 1-, 3-, and 5-year actuarial survival rate was 80%, 62%, and 44%, respectively. The overall local control rate at 1 and 5 years was 75% and 65%, respectively, and distant failure was documented in 44% of patients. Subgroup analysis revealed that the presence of gross disease after surgical resection was the strongest prognosticator, with a 5-year survival and local control rate of 17% and 50%, respectively, compared with 60% and 68%, respectively, for microscopic disease. The local control rates of patients with new primaries were similar to those of patients treated for recurrent disease (63% vs. 71%), probably because gross residual disease occurred only in the group of patients with new primaries. The addition of EBRT to IOHDR increased the 5-year disease-free survival rate from 27% to 44% but had no effect on local control (64% vs. 65%).

IOHDR can be safely used to deliver a high radiation dose to locally advanced and recurrent tumors in the paranasal sinuses. In an attempt to improve outcome, we are now adding limited-dose EBRT (20-30 Gy) after 17.5 Gy of IOHDR in previously irradiated patients and increasing the EBRT dose for both microscopic (50-54 Gy) and gross residual disease (60-65 Gy) after 15 Gy of IOHDR in previously unirradiated patients. Chemosensitization should also be considered in previously irradiated patients and in those with gross residual disease. Interstitial boosting techniques, which can deliver higher doses at depth, should also be considered in patients with gross residual disease.