Salivary glands radiotherapy to reduce sialorrhea in amyotrophic lateral sclerosis: dose and energy

Purpose: This retrospective study evaluated the effectiveness of salivary gland radiotherapy for reducing sialorrhea in patients with amyotrophic lateral sclerosis (ALS).

Patients and methods: From August 2001 to February 2008, 21 patients with amyotrophic lateral sclerosis (six men, 15 women; mean age 61.2 years, range 39-81) received external beam radiotherapy for sialorrhea (evaluation by the ALS Functional Rating Scale). All patients had previously received pharmacological treatments with unsatisfactory results or side effects. The mean dose was 19.1Gy (range 3-48), delivered in five fractions (range 1-16) on 17 days (range 1-77). Eight patients received 3D-conformal and 13 received 2D-conformal radiotherapy. Clinical target volumes included the parotids and submandibular glands (18 patients), submandibular glands and one parotid (one patient), or parotids (two patients). Thirteen patients were treated with 5.5-6MV photons and eight were treated with 6-15MeV electrons. A satisfactory salivary response was defined as complete or partial improvement. The median follow up was 10.4 months (range 0.4-26). One patient was lost to follow up.

Results: A positive response was observed in 65% of patients during a mean of 7 months (range 1-23). Four patients (20%) treated with photons and no patients treated with electrons experienced acute toxicity. Half (50%) the patients treated with photons and 87.5% of patients treated with electrons responded positively (P=0.09). Positive responses were more common with a high total dose (≥16Gy; 78.6%) than a low total dose (<16Gy; 33%; P=0.07). No differences were observed in tolerance (P=0.27). Age and sex did not impact the response.

Conclusion: Salivary gland radiotherapy effectively reduced sialorrhea in patients with amyotrophic lateral sclerosis. An adequate compromise between toxicity and efficiency was achieved with 3D-conformal radiotherapy delivered with electrons to parotids and submandibular glands in a total dose of 16Gy or more (mean: 20Gy in five fractions).