Background: Shortening the duration of radiation therapy would benefit women with early breast cancer treated with breast conservation. It may also improve access to radiation therapy by improving efficiency in radiation oncology departments globally. This can only happen if the shorter treatment is as effective and safe as conventional radiation therapy.
Objectives: To assess the effects of altered fraction size on women with early breast cancer who have undergone breast conserving surgery.
Search strategy: We searched the Cochrane Breast Cancer Group Specialised Register (June 2006), MEDLINE (November 2006), EMBASE (November 2006), reference lists for articles, and relevant conference proceedings. No language constraints were applied.
Selection criteria: Randomised controlled trials of unconventional versus conventional fractionation in women with early breast cancer who had undergone breast conserving surgery.
Data collection and analysis: Data extraction was performed independently by the authors with disagreements resolved by discussion. Missing data was sought by contacting the authors concerned.
Main results: Two trials were included and reported on 2644 women. The women were highly selected with node negative tumours smaller than 5 cm and negative pathological margins; 46% of the women had a cup separation size of less than 25 cm. The studies were of high quality. Data for local recurrence and breast appearance were not available in a form which could be combined. Unconventional fractionation (delivering radiation therapy in larger amounts each day but over fewer days than with conventional fractionation) did not appear to affect: (1) local-recurrence free survival (absolute difference 0.4%, 95% CI -1.5% to 2.4%), (2) breast appearance (risk ratio (RR) 1.01, 95% CI 0.88 to 1.17; P = 0.86), (3) survival at five years (RR 0.97, 95% CI 0.78 to 1.19; P = 0.75), (4) late skin toxicity at five years (RR 0.99, 95% CI 0.44 to 2.22; P = 0.98, or (5) late radiation toxicity in sub-cutaneous tissue (RR 1.0, 95% CI 0.78 to 1.28; P = 0.99).
Authors' conclusions: We have evidence from two high quality randomised trials that the use of unconventional fractionation regimes (greater than 2 Gy per fraction) does not affect breast appearance or toxicity and does not seem to affect local recurrence for selected women treated with breast conserving therapy. These are women with node negative tumours smaller than 5 cm and negative pathological margins. Two new trials have been published in March 2008. Their results are consistent with our findings. The results of these trials will be incorporated in the next update of this review.