Date of Award

1-1-1998

Document Type

Thesis

Publisher

Edith Cowan University

Degree Name

Doctor of Philosophy

School

School of Nursing

Faculty

Faculty of Health and Human Sciences

First Supervisor

Professor Linda Krisijanson

Second Supervisor

Dr Sue Nikoletti

Third Supervisor

Dr Fiona Cameron

Abstract

Skin reactions are unavoidable side effects of radiotherapy for breast cancer that may limit the amount of treatment a patient is able to receive. As well, the discomfort associated with the treatment may negatively affect the patient's quality of life and their willingness to complete a course of treatment that typically extends over seven weeks. Prior literature suggests that variations in patients' tissue reactions to radiation may be related to Individual patient characteristics. Before health care providers can intervene to prevent or minimise skin reactions, a clinical model that helps predict which patients will experience more skin reactions is needed. The purpose of the study was twofold: firstly, to test the theoretical relationships between factors that impair healing and the severity of radiation skin reactions; and secondly, to develop a model to predict the severity of radiation skin reactions in women being treated for breast cancer. The theoretical framework for the study was based on two bodies of knowledge, radiobiology and wound healing. This framework specified three sets of potential predictors of radiation induced skin reactions. These were radiation factors (e.g. dose, fractionation), genetic factors (e.g. personal and family history or cancer, radiosensitive conditions) and personal factors (e.g. age, smoking history, nutritional status). It was hypothesised that the severity of the skin reaction was a function of the relationship between these constructs. A sample of 126 women was recruited to the study over a 14-month data collection period. All the women had undergone lumpectomy and were commencing a standard radiation protocol of 45 Gray to the whole breast delivered in daily fractions of 1.8 Gray over five weeks, and a 20 Gray electron boost to the lumpectomy site delivered in daily fractions of 2 Gray over two weeks. After obtaining written informed consent, data on potential factors were collected by interview at the commencement of treatment and from the medical records. Weekly observations of the skin using the Radiation Therapy Oncology Group scoring system were recorded throughout the seven weeks of treatment. The breast was divided into eight anatomical sites to increase specificity in the final analysis. The mean inter-rater reliability of RTOG scoring between the three observers was 0.85. Chi square analysis revealed that several factors were associated with a more severe reaction. Significant factors from the "personal construct" included smoking, chemotherapy, history of skin cancer, reaction of the skin to UV radiation, lymphocele aspiration, condition of the lumpectomy scar at the commencement of treatment, weight, and the size of the breast. Stepwise logistic regression analysis revealed the relative risk and predictive value of the factors. A predictive model was developed for each of the eight anatomical Sites of the breast for weeks three to seven of radiation treatment. The principal predictors were a large breast size, smoking during the treatment period, and having had a lymphocele aspirated on at least one occasion prior to radiotherapy. The results show that it is possible to predict the severity of skin reactions in individual patients. The research contributes to theory development in radiation skin reactions and to the practice of radiation oncology nursing. Practice implications centre on individualising the preparation, education and management of women undergoing radiation therapy for breast cancer. Further research with larger samples and using different anatomical sites will contribute to the development of a skin reaction risk assessment tool for general use in radiation oncology nursing.

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