Abstract
Radiation skin reactions are a common side effect of radiation therapy and can be distressing and painful for patients. Head and neck cancer patients receive a high dose of radiation to the skin and are therefore at high risk of acute skin toxicity. There have been many clinical trials investigating topical agents to reduce or prevent these reactions but the evidence to date is lacking and many centres still base their practice on anecdotal evidence. Recently clinical trials in breast cancer patients have shown that using Mepitel Film® (Mölnlycke Health Care AB, Gothenburg, Sweden) reduced skin reaction severity and stopped the development of moist desquamation when used prophylactically (from the first day of radiation therapy). Mepitel Film and other soft silicone dressings that adhere very closely to the folds of the skin, have been hypothesized to decrease skin reaction severity by stopping friction by clothing and allow the radiation damaged skin to repair itself.
The aim of this randomised controlled feasibility study in this thesis was to investigate whether Mepitel Film dressings were superior to Sorbolene cream in reducing or managing radiation-induced skin reactions in patients with head and neck cancer Head and neck cancer patients are prescribed a higher dose than breast cancer patients, have an uneven surface for the Mepitel Film to adhere to and have complex non-homogenous dose distributions, This means that testing the effect of Mepitel Film in this cohort would be challenging. Despite this, it was hypothesised that Mepitel Film was superior to standard Sorbolene cream in decreasing the severity of acute radiation-induced skin reaction in patients receiving radiation therapy for head and neck cancer.
In order to test this hypothesis a randomised, controlled, multi-centre, international, open label intra-patient feasibility study was conducted in New Zealand and China. This thesis analyses a subset of 12 patients recruited at the Canterbury Regional Cancer and Haematology Service (CRCHS) at Christchurch Public Hospital. For the first six patients, the study area was chosen as the area of first erythema which was divided into equal halves. Each half was randomised to either Mepitel Film or Sorbolene cream. Mepitel Film was applied as soon as erythema was visible (management protocol). For the next six patients, the study area was chosen at the planning stage to include an area of relatively uniform high dose (>40Gy). This area was divided into two equal halves; one half was randomised to Mepitel Film the other half to Sorbolene cream. Mepitel Film was applied from day one of radiation therapy treatment (prophylactic protocol). Sorbolene cream was applied twice a day by the patient. The Modified Radiation-induced Skin Reaction Assessment Scale (RISRAS) and the Modified Radiation Therapy Oncology Group (RTOG) skin toxicity score were used to assess skin reaction severity three times a week. Patients also filled out the New Zealand validated Distress screening tool once a week and completed exit questionnaires at the end of the follow-up period. Thermoluminescent dosimeters (TLDs) were used to measure the actual dose to the skin underneath Mepitel Film and the control cream for all patients.
When results of all 12 patients were combined, there was a statistically significant decrease in skin reaction severity in favour of Mepitel Film of 29% for combined scores, of 15% for researcher scores and of 49% for patients’ scores (p= 0.001, 0.002 and 0.004 respectively). The difference in peak RISRAS score between skin covered with Mepitel Film and control skin covered in cream was also significantly lower (p=0.02). The results were disappointing compared to those reported by the breast cancer trial where skin reaction severity was reduced by more than 90% when Mepitel Film was used prophylactically. Several factors may explain the lack of effectiveness of the Mepitel Film in this patient cohort. Dose to the skin was significantly higher in head and neck cancer patients and Mepitel Film did not adhere well to skin with heavy beard stubble, which meant Mepitel Film needed to be replaced almost daily for the first few weeks of radiation therapy. The latter may also explain why there was no difference in the Mepitel Film effect between the skin of patients on the management protocol and those on the prophylactic protocol which should have had the strongest skin protective effect. In addition, compared with skin covering the breast area, skin in the neck area may be “tougher” and less likely to benefit from “friction protection”.
The results suggest that Mepitel Film does reduce skin reaction severity in head and neck cancer patients but the increase in skin folds, beard growth and high skin dose mean that the protective effects of Mepitel Film are limited, particularly in men with heavy beard growth. Mepitel Film appeared to be more effective in women but there were too few women in this trial to perform a statistically meaningful analysis. Future research should include clinical studies in different cohorts of head and neck patients, such as in women and men with less beard growth.