Trial shows that partial breast irradiation can result in greater damage to the breast

A clinical trial comparing a shorter course of partial breast irradiation with standard whole breast irradiation has found that those who received the faster partial treatment were more likely to report side effects and poorer cosmetic outcomes.

New Zealand women were involved in the RAPID clinical trial which compared partial breast irradiation given twice daily over five to eight days with whole breast irradiation given daily over three to five weeks.

The latest results come after a three-year follow-up in which nurses, oncologists and the women concerned were asked to rate the cosmetic outcome of the treatment as excellent, good, fair or poor.

Those who had partial breast irradiation were deemed more likely by all three groups to have a ‘fair or poor’ cosmetic result, when compared with those who had full breast irradiation.

Oncologists rated 35 per cent of those who had partial breast irradiation as having a ‘fair or poor’ cosmetic result, compared with 19 per cent for those who received full breast irradiation.

Nurses rated 32 per cent of the women who had partial breast irradiation as having a ‘fair or poor’ cosmetic result, compared with 19 per cent of the women who had full breast irradiation.

Women who received the partial breast irradiation were also reported to have a mild to moderate increase in side effects such fibrosis (hardening of breast tissue) and telangiectasia (small, visible blood vessels on the skin of the breast).

Severe side effects were rare in both groups and there were no life-threatening side effects.

BCAC chair Libby Burgess says the results are an important step in setting the standard for world class radiation treatment for breast cancer.

“While it would have been nice to have this shorter more convenient course of radiation treatment, the results of this study suggest the side effects are unacceptable.  Women who have the less intensive longer course of radiation treatment will suffer less damage to their breast and end up with a better cosmetic result.”

The trial researchers will continue to monitor the more than 2000 women involved in the trial to determine whether partial breast radiation is as effective as whole breast radiation in preventing the recurrence of breast cancer.

The RAPID trial is run by the Ontario Clinical Oncology Group.

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