Efficacy of hydrolytic enzymes in preventing radiation therapy-induced side effects in patients with head and neck cancers.

Purpose: Based on in vitro and on clinical evidence of protection against acute side effects of radiation, a prospective randomized, open study was performed to determine the efficacy of an oral proteolytic enzyme preparation in patients with head and neck cancer receiving conventional fractionated radiation therapy.
Methods: Patients with stage T3/T4 head and neck cancer were eligible. One hundred patients from two centres were entered into the study. 60Co gamma-radiation was delivered at a standard daily radiation dose of 2 Gy in 25-35 fractions over a period of 6-7 weeks. Two lateral parallel opposing fields were used with a portal area of 10 x 15 cm. Patients assigned to the test group arm additionally received enzyme tablets orally t.i.d. starting 3 days prior to radiation therapy, and continuing up to 5 days after completion of the course of radiation therapy. Patients in the control arm were not given any drug or placebo. Acute radiation side effects were described as mucositis, skin reaction, dysphagia, and were graded at each visit during and after radiation therapy, following RTOG/EORTC criteria.
Results: The severity (maximum extent) of acute radiation therapy side effects was significantly less in enzyme-treated patients than in control patients: mucositis (mean: 1.3 vs 2.2, P < 0.001), skin reaction (1.2 vs 2.4, P < 0.001) and dysphagia (1.4 vs 2.2, P < 0.001). The duration of these side effects as well as the sum scores of side effects were also less in the study arm.
Conclusions: Combination of enzyme therapy with conventional fractionated radiation therapy was feasible and well-tolerated. There was significant protection against acute side effects of radiation therapy in the study arm. Not only was the severity of acute side effects less but the duration was shorter and the time to onset was also delayed. Prospective randomized double-blind studies would verify this role of an oral enzyme therapy as standard co-medication with radiation therapy to the head and neck region.