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 the update of a Cochrane Review in July 2016, Brigid Hickey and colleagues from the Princess Alexandra Hospital in Brisbane Australia examined the research on the use of partial breast irradiation and she tells us what they found in this Evidence Pod.

Brigid: “For most women diagnosed with early breast cancer, breast conserving therapy in which surgery to remove the tumour is followed by a course of radiation therapy has been shown to be as safe as mastectomy, in which the whole breast is removed. This allows most women to choose to keep their breast if they wish to do so.
Radiation therapy, delivered to the whole breast and requiring 21-30 visits to a Radiation Therapy Department reduces the risk of cancer recurring in the treated breast. Most of these local recurrences would occur at the site of the original tumour bed and it’s uncertain whether radiation therapy can prevent so called “elsewhere” primaries, which are new tumours in other parts of the same breast.
We did this Cochrane Review to investigate whether confining the radiation treatment to the tumour bed results in similar cancer-related and cosmetic outcomes as whole breast irradiation. This partial breast irradiation can be delivered in fewer treatments, with a resultant decrease in the volume treated.
We were able to include data from nearly 7600 women in seven randomised trials, done over the last couple of decades. We found no data with respect to costs, quality of life and patient preference; but findings were mixed for the effects of partial breast irradiation on other outcomes. There was low quality evidence that local recurrence-free survival and cosmetic outcomes were worse, high quality evidence that overall survival did not differ between the different types of radiotherapy and moderate quality evidence that late radiation toxicity (subcutaneous fibrosis) was worse with partial breast irradiation. Acute toxicity was reduced with the use of partial breast irradiation, but elsewhere primaries were more common. Breast cancer-specific survival, distant metastasis-free survival, relapse-free survival and loco-regional recurrence-free survival did not appear to differ.
In summary, it appears that there is a small increase in local recurrence and 'elsewhere primaries' (new primaries in the same breast as the original tumour) when partial breast irradiation is used, but we found no evidence of detriment on other oncological outcomes. It appears that cosmetic outcomes and some late effects are worse with partial breast irradiation, but its use was associated with less acute skin toxicity. The limitations of the data currently available mean that we cannot make definitive conclusions about the efficacy and safety or ways to deliver of partial breast irradiation, and this needs to await the completion of ongoing trials.

John: If you’d like to read more about the current evidence and watch for updates of this review as the findings of those ongoing trials get added to future updates, you can find it at Cochrane Library dot com with a search for ‘partial breast irradiation’.