John: Hello, I'm John Hilton, editor of the Cochrane Editorial unit. For many women with breast cancer, the use of post-operative radiotherapy will allow them to undergo less extensive surgery. In July 2016, Brigid Hickey from the Princess Alexandra Hospital in Brisbane Australia and colleagues published an update of their Cochrane Review examining the research on the size of the doses in which the radiation is given. She tells us what they found in this Evidence Pod.

Brigid: Most women with early breast can choose to keep their breast. If the tumour is removed (with negative margins), and a course of radiation therapy delivered (called breast conservation) this is as effective as a mastectomy. Conventionally fractionated radiation therapy entails 25-30 visits to a Radiation Therapy Department, with treatments delivered in 1.8-2Gy Gy fractions over 5-6 weeks. We assessed whether using fewer radiation therapy treatments (hypofractionation) delivered at more than 2Gy per fraction over 21-26 days is as safe and effective. For fewer radiation treatments to be as effective as conventionally fractionated radiation therapy, the new treatment must provide the same cancer-related outcomes and comparable cosmetic outcome.
We searched systematically and found 9 randomised controlled trials addressing this issue.
The population studied included 8228 women with small-medium breasts and completely excised, node negative breast cancer.
We found high quality evidence that the use of fewer treatments had no clinically meaningful effect on local recurrence-free survival, cosmetic outcome or overall survival.
Acute radiation toxicity was decreased with hypo-fractionation and we found high quality evidence that late subcutaneous toxicity (fibrosis) did not differ. Breast cancer-specific survival and relapse-free survival did not differ. We found no data with respect to mastectomy rate with hypofractionation.
Patient and physician-reported fatigue was reduced with fewer treatments at six months and other patient-reported measures of quality of life did not differ.
In selected women with early breast cancer (with negative margins and size 3 cm or less, with small to medium sized breasts), shortened fractionation regimens are not detrimental for cancer-related outcomes. There still remains uncertainty about the effect of altered fraction size on ischaemic heart disease, although new radiation techniques, which avoid treating the heart, mean this is of less importance.

John: For fuller information on the different outcomes studied in this review and the technical details on the types of radiotherapy that were compared, go to Cochrane Library dot com and search ‘fraction size and breast radiation’.