The use of radiation therapy in the management of minor salivary gland tumors.

Between 1964 and 1985, 52 patients were treated with curative intent by radiation therapy alone or in combination with surgery for malignant tumors of minor salivary gland origin. All patients had a minimum follow-up of 2 years, and 80% had a minimum follow-up of 5 years. Twenty-six (50%) were adenoid cystic carcinomas; the remaining histologies included adenocarcinoma, mucoepidermoid carcinoma, and malignant mixed tumors. The most common sites of origin were in the oral cavity/oropharynx (49%) and the nasal cavity or paranasal sinuses (40%). Twenty-seven patients (52%) presented with an advanced or unresectable stage (AJCC Stage III or IV, extensive bone or nerve invasion, or tumor greater than 5 cm). Treatment was highly individualized; 50% of the patients received radiation therapy alone, and 50% received combined treatment with either postoperative or preoperative radiation therapy. Early-stage minor salivary gland tumors were controlled equally well with radiation therapy alone or with a combined approach. For the advanced tumors, a combined approach yielded significantly superior absolute local control rates as compared with radiation therapy alone (10/13 vs. 2/13). For adenoid cystic carcinoma, the local control rate at 10 years was 45% (actuarial); the tumor was not controlled locally in any patients with advanced/unresectable stage who were treated with radiation therapy alone. The absolute local control rate was 75% for 4 early-stage tumors treated with radiation therapy alone and 60% for 5 advanced tumors treated with a combined approach. The average time to local recurrence was 67 months for adenoid cystic carcinoma. Severe complications of radiation therapy occurred in 11 (27%) of 40 evaluable patients, with unilateral blindness being the most common. Seven of 9 patients who became blind had unresectable disease with close proximity to or invasion of the orbit. A time-dose analysis is also presented.