London, Mar 19 : Lesser use of radiation therapy, but higher doses appear to be just as effective as conventional doses for women recovering from breast cancer, suggests a new research which involved two studies.
Trials involving nearly 4,500 women with early breast cancer have shown a lower total dose of radiotherapy, delivered in fewer, larger treatments, has been shown to be as effective as the international standard of a higher total dose delivered over a longer time.
Currently, the internationally accepted standard for treating early breast cancer is to give 50 Gray of radiation in 25 separate "fractions", of 2 Gray each, over five weeks.
The decade-long research results, published in the Lancet and Lancet Oncology, confirm long-held beliefs of some cancer specialists in the UK who have been using shorter treatment schedules for some time.
The trials, called Start A and Start B, short for UK Standardisation of Breast Radiotherapy Trial, were jointly funded by Cancer Research UK, the Medical Research Council and the Department of Health. In START A, John Yarnold at the Institute of Cancer Research in Sutton, UK and colleagues recruited 2236 women with early breast cancer from 17 centres around the UK.
After surgery, the women were randomly assigned to one of three groups: either 39 Gray in 13 fractions, 41.6 Gray in 13 fractions, or the standard 50 Gray in 25 fractions. All treatments lasted five weeks.
"We wanted to isolate the effect of fraction size," New Scientist quoted Yarnold, as saying.
After five years, tumour relapse was as good in the 41.6 Gray group, in which each dose was 3.2 Gray, as in the standard treatment group which got 2 Gray per dose. A second study, START B, led by the same team of researchers, divided 2215 women into two groups. One group got the standard treatment and the other got just 40 Gray in 15 fractions over three weeks. The experimental group not only showed fewer adverse effects after six years of follow up, but they also had a lower rate of tumour relapse - 2.2percent versus 3.3 percent.
A small difference, but statistically significant. The authors write that this regimen is "at least as good as" the international standard.