Exposure of the oesophagus in breast cancer radiotherapy: A systematic review of oesophageal doses published 2013–2018

Background: Breast cancer radiotherapy has been shown to increase the risk of subsequent primary oesophageal cancer. It is unclear if avoidance of the oesophagus is being considered routinely during radiotherapy treatment planning. This study aims to describe exposure of the oesophagus from modern breast cancer regimens.

Material and Methods: A systematic review of oesophageal doses from breast cancer radiotherapy regimens published during 2008–2018 was undertaken. Average mean oesophageal doses and average maximum oesophageal doses were described for different anatomical regions irradiated and techniques used. Oesophageal exposure from current modern regimens was compared to that received in previous decades.

Results: Seventy-three regimens from 16 countries reporting oesophagus doses were identified. The average mean oesophagus dose was 0.2 Gy (range 0.1–0.4) for partial breast irradiation, 1.5 Gy (Range 0.1–10.4) for whole breast/chest wall radiotherapy and 14.2 Gy (range 1.1–29.3) with the addition of regional nodal irradiation. For regimens that included regional nodal irradiation, the average mean oesophageal dose was higher for IMRT (21.6 Gy static IMRT, 13.6 Gy rotational IMRT) than tangential radiotherapy (5.5 Gy) (p < 0.001). Overall, average oesophageal exposure from modern regimens was similar to that estimated from regimens used in previous decades.

Conclusions: Exposure of the oesophagus remains an issue in modern breast cancer radiotherapy. Routine avoidance of the oesophagus during treatment planning may reduce the number of women developing a subsequent primary oesophageal cancer in the future.