Intensity-modulated radiation therapy (IMRT) (photo: Jan Chlebik/the ICR)
Small skin samples can be used to predict the likelihood of rare but severe side-effects that can occur years after radiotherapy for breast cancer, according to new research.
The results could help to identify the small number of women at risk of a severe reaction after radiotherapy.
Around 1 in 10 women treated with radiotherapy for primary breast cancer experience breast shrinkage, hardness and pain many months or years after treatment. In a minority of these women the reactions are severe, significantly affecting quality of life.
Some studies have suggested that radiation damage to fibroblasts – specialist cells that help to rebuild tissue during healing – may be the cause, but research has not been conclusive.
Scientists from The Institute of Cancer Research, London, working with colleagues across Europe, took tiny skin biopsies from women treated for breast cancer and viewed the women’s fibroblast cells using advanced microscope techniques.
Left: Fibroblasts in the lab, harvested from breast skin sections. Right: Cells stained to highlight p53-binding protein 1 (seen as dots, or foci) – each dot represents an area of damage to the cell’s DNA that is attempting repair (photo: the ICR)
They analysed the amount of damage to the cells after they were exposed to radiation. They were looking for a specific protein called p53-binding protein 1 (53BP1), which helps to ensure correct DNA repair and forms clusters called ‘foci’ where a cell’s DNA is damaged.
Hope for validated test
The researchers found that the number of 53BP1 foci remaining in tissue exposed to radiation was related to the side-effects that women experienced after radiotherapy. This suggests that the levels of 53BP1 foci remaining in an individual’s fibroblast cells could be used to predict if a woman would experience late toxicity from radiotherapy.
Dr Navita Somaiah from the ICR’s Division of Radiotherapy and Imaging said: “These fibroblast cells derived from women with breast cancer are helping us to determine if they will suffer the long-term side-effects of breast shrinkage and hardening following radiotherapy – it could even tell us how severe these might be. We hope further research will help to provide a validated test that could be used in the clinic.”
The findings were published in Cancer Letters and received support from The Royal Marsden Hospital Charity, as well as NHS funding to the National Institute for Health Research Biomedical Research Centre at The Royal Marsden and the ICR, and to the Centre for Research in Health Protection at Public Health England.