• Frequency of moist desquamation (grade 3) acute skin reaction scored as worst reaction within allocated skin care area [ Time Frame: 12 weeks ]
  

• Skin toxicity area under the curve (AUC) being sum of maximum skin reaction per week over 12 weeks [ Time Frame: 12 weeks ]
  

Skin reactions are a common and undesirable result of radiation treatment. Preventative measures are often used although there are few controlled trials. Commonly employed agents for established reactions have included sorbolene (10% Glycerine), silver sulphadiazine, hydrocolloid dressings, topical steroids, salt water or bicarbonate of soda water solution bathing and hydrogen peroxide. One trial found that Cavilon No-Sting Barrier film reduced Grade 3 skin reaction compared to sorbolene, although this film did not contain any moisturising agents.

General Hypothesis: That in a paired double blind randomised study peak and overall skin reactions experienced by post mastectomy breast cancer patients receiving radiotherapy may be reduced by Cavilon Durable Barrier Cream (CDBC) compared to Sorbolene.

Alternative Hypothesis of primary outcome: the frequency of grade 3 or more skin reaction will be reduced from 35% to 25% for skin care using sorbolene or CDBC respectively.

Alternative Hypothesis of secondary outcome: the mean area under the curve (AUC) of total skin reaction will be reduced from 9 to 8 for skin care using sorbolene or CDBC respectively.