IMRT reduces side effects of breast cancer treatments
Washington: Treating early breast cancer patients with an advanced form of radiotherapy known as Intensity modulated radiotherapy (IMRT), gives better results than the standard treatment, according to a new study.
IMRT is an advanced, high-precision form of radiotherapy that can deliver an even dose of radiation, thus reducing the cosmetic problems that can often occur after breast radiotherapy.
"We believe that this study, the largest prospective trial in the world to test breast IMRT against standard two-dimensional radiotherapy, will be practice-changing at an international level," said Dr Charlottes Coles , from Addenbrooke`s Hospital Oncology Centre, Cambridge, UK. "Analysing the results five years after treatment, we saw significant benefits in patients who had received IMRT."
The researchers analysed the radiotherapy treatment plans of 1145 patients with early breast cancer who had previously had breast-conserving surgery. The plans were screened to see if they would produce an uneven radiation dose with standard two-dimensional radiotherapy (2DRT). A total of 71 percent of the plans fell into this category, and those patients were randomised between standard 2DRT and IMRT. The 29 percent of patients whose plans would not produce an uneven dose were treated with standard 2D RT, but still followed up within the trial.
One of the aims of external radiotherapy is to treat the target - in this case the whole breast - with an even dose distribution, i.e. within a range of 95 percent to 107 percent of the prescribed dose. Too low a dose can risk tumour recurrence, and too high a dose can cause undesirable side-effects such as skin changes.
"The problem with 2D breast radiotherapy is that the dose distribution is only recorded across the central part of the breast. Usually it meets the 95-107 percent constraints, but the shape of the breast changes, so if the same plan is looked at in 3D, then there may well be areas with overly high doses. By modulating the intensity of the radiation beam, IMRT can be used to correct for this and smooth out the dose," said Dr Coles.
The researchers set out to see whether the effect of using IMRT in those patients who would have received a dose greater than 107 percent to parts of their breast with 2DRT would translate into clinical benefit. IMRT planning uses results from scans to determine the dose intensity that will best treat the tumour, and therefore is more complex and time-consuming than 2DRT planning, so there was an important need to see a clear advantage to patients from the use of the procedure.
"We saw that fewer patients in the IMRT group developed skin telangiectasia (dilated blood vessels near the surface of the skin), and the overall cosmetic effect in the breast was better," she said. Although there was no significant difference between the two groups in breast shrinkage, breast oedema, breast induration (hardening), and pigmentation changes, the benefits of using IMRT in these patients were clear.
The researchers intend to follow up their work by analysing the patients` questionnaires to see whether IMRT has an influence on quality of life.
The study was presented to the 2nd Forum of the European Society for Radiotherapy and Oncology (ESTRO).