The Cambridge breast intensity modulated radiotherapy trial

Radiotherapy (RT) following conservation surgery for breast cancer has been proven to improve both local control and survival. Currently, the challenge is to minimise RT-induced side effects without losing efficacy. Conventional 2D RT breast plans can lead to substantial dose inhomogeneities, which may cause a worse cosmetic result. This is important to patients, as a poor cosmetic result can cause significant psychological morbidity. Planning studies have shown that breast dose homogeneity can be improved with 3D planning and intensity modulated radiotherapy (IMRT). However, there is very little evidence regarding the clinical benefit of IMRT for breast cancer. This unique NCRN-adopted randomised controlled trial will test the clinical benefit of IMRT for women with early breast cancer.

The primary question is: does correction of dose homogeneity using forward-planned IMRT improve the cosmetic outcome in patients with early breast cancer? Patients with significant dose inhomogeneities with 2DRT are randomised to IMRT or standard 2D RT. High-quality normal tissue toxicity and cosmesis data are being collected, including a novel analytical method of breast volume measurement using a 3D laser camera.

Eight hundred and eighty-five patients have been recruited to date, and accrual of 1,000 patients is on target for January 2007. A high-quality radiographer-led 3D breast radiotherapy service has developed as a direct result of the trial. Blood DNA samples from trial patients will enable investigation of individual genetic variation in normal tissue radiosensitivity within a multicentre translational radiogenomics study.

The results from this trial could provide impetus to improve the quality of breast radiotherapy for many women worldwide. The DNA database will greatly contribute to the ultimate aim of individualised radiotherapy based on genetics.