Study finds risks of radiotherapy outweigh benefits

Radiotherapy, a mainstay of breast cancer treatment for decades, may do more harm than good for many women.

Radiotherapy, a mainstay of breast cancer treatment for decades, may do more harm than good for many women.

An analysis of 40 scientific trials involving 20,000 women has found that although irradiating the breast reduces the risk of local recurrence of cancer, it increases the risk of death from other causes, especially of the circulation.

The finding - from the same group that reported the remarkable 30 per cent fall in breast cancer deaths in the UK, which has saved 20,000 lives over the past decade - highlights the importance of directing treatment at the right patients. The hormone-based drug Tamoxifen is thought to be the chief reason for the improvement in survival but radiotherapy, while saving the lives of some, may have hastened the deaths of others.

More than 30,000 women a year develop breast cancer and most receive radiotherapy. It is used widely on women having less extensive surgery - lumpectomy rather than mastectomy - to try to control any remaining cancer cells.

For older women, and those at low risk of local recurrence of their breast cancer, researchers from the Imperical Cancer Research Fund Clinical Trial Service Unit in Oxford say the net effect of radiotherapy given 20 years ago appears to have been "unfavourable". Only younger women with a high risk of recurrence of breast cancer have benefited.

Delivering radiation to the breast area after surgery to reduce the risk of the cancer returning has been practised for almost 50 years. But this exposes the heart and major arteries to radiation, increasing the risk of circulatory disease.

The study, published in The Lancet, shows that after the second year of survival, before which radiotherapy has little effect, the treatment cuts deaths from breast cancer by 13.2 per cent but increases deaths from other causes by 21.2 per cent.

After 20 years, the researchers found 37 per cent of women who had radiotherapy were still alive compared with 36 per cent of those who did not have it - a 1 per cent difference.

Professor Rory Collins, one of the authors of the study, said yesterday that the findings should be seen positively. "Targeting treatment is a good thing and now we have the data to do that. The findings relate to radiotherapy in the past. The hope is that with newer radiotherapy regimens we can avoid the hazards by closer targeting to the tumour, away from the heart and arteries."

The findings show that women under 50 with breast cancer that has spread to the lymph nodes gain the most from radiotherapy, as they have the highest risk of a recurrence. After 20 years they had a 5 per cent survival advantage.

But for other women the position is less clear. Professor Collins said: "For women with low risk of recurrence the benefits of radiotherapy are very small - 1 per cent or less at 20 years. It would be reasonable for them to ask whether it is worth it even if it were possible to avoid all the hazards."

Modernradiotherapy techniques focus the beam more tightly on the affected area, reducing the hazards and benefiting more patients. Results from a Danish study using these techniques published last year showed substantial protection against recurrence of breast cancer with no increase in deaths from other causes.

But Professor Collins warned: "The patients have been followed up for only 10 years - too short to detect any hazard. At the moment the argument is theoretical."