Phase II study of vitamin E and pentoxifylline in patients with late side effects of pelvic radiotherapy

Abstract

Background and purpose: Radiation-induced tissue fibrosis is a common adverse effect of curative treatment for pelvic cancer. Pilot studies testing alpha-tocopherol and pentoxifylline provide evidence of clinical regression of superficial radiation fibrosis after radiotherapy.

Patients and methods: Twenty-seven eligible research volunteers with a minimum of one grade 3 or 4 disability (LENT SOMA) due to previous radiotherapy were entered into the study. Volunteers were given dl-alpha tocopheryl acetate 500 mg twice a day orally plus pentoxifylline 400mg twice a day orally over a period of 6 months. Clinical assessment of late side effects recorded using LENT SOMA scales was selected as the primary endpoint, taken at baseline and at 6 and 12 months post-registration. Patient self-assessment of function and quality of life was assessed as a secondary endpoint using the EORTC QLQ-C30 core questionnaire and the EORTC QLQ-CR38 pelvic module. Magnetic resonance imaging was undertaken in 13/23 evaluable volunteers before and after 6 months of therapy.

Results: At 12 months post-registration there were 4 out of 23 responders. At 6 months post-registration there was a statistically significant improvement (i.e. reduction) in the median of the LENT SOMA summed scores in all areas assessed apart from 'male sexual dysfunction', 'vulva' and 'vagina' which were unchanged at 6 months. The median total LENT SOMA score at baseline and 6 months was 49 and 34, respectively, with a median change in total LENT SOMA score between baseline and 6 months of 9 (IQR 7-18) (P<0.001). The maximum LENT SOMA scores improved over the study period, with a total number of 82 maximum grade 3 or 4 normal tissue scores at baseline (median of four complications per person) reduced to a total number of 67 maximum grade 3 or 4 scores at 6 months post-registration (median of 3 complications per person), i.e. a median reduction in severe complications of one per person. LENT SOMA scores at 12 months were similar to those observed at 6 month suggesting no further improvement nor deterioration in late side effects. These findings were, however, not reflected in the patient self-assessment of function and quality of life, raising question about the possibility of observer bias in recording LENT SOMA scores. No significant changes were reported on magnetic resonance images at 6 months from baseline.

Conclusions: Despite only seeing four a priori defined responders in this pilot study testing dl-alpha tocopheryl acetate plus pentoxifylline in patients suffering complications of pelvic radiotherapy, changes in LENT SOMA scores suggest beneficial effects. However, we are not convinced that these effects are real, since no significant changes in symptoms and functional status were recorded by detailed prospective patient self-assessments.