Finding new ways to predict if hormone treatment is working

Hormone treatments, such as tamoxifen, can be very effective at treating oestrogen receptor (ER) ‑positive breast cancers. However, the treatment unfortunately does not work for all women, as some breast cancers are either resistant from the start or become resistant over time. We need to find ways to tell as early as possible whether these treatments are working, to ensure that the women who they are not working for can avoid the unpleasant side effects of drugs that are not helping them, and can instead be given something more effective for them.

A recent study has found that the chance of breast cancer coming back was lower in women who, whilst taking hormone therapy, had seen a reduction in their breast density, measured using mammograms. This suggests that the change from high breast density to lower density could be preventing women from seeing their cancer return – but studies investigating this link have so far have been too small to give conclusive evidence.

Jane is leading a large, multi-centre study to confirm whether a change in breast density can be used to determine how well hormone therapy is working, and how likely it is to be stopping the cancer from returning.

Her team are gathering mammogram images from 2,000 women who have had breast cancer and are being treated with hormone therapy. The women will have mammograms at their initial diagnosis as well as 1 year and 3 years after breast conservation surgery. From these images, she is determining the amount of dense tissue in the breast, and its pattern of distribution, and how these change over the course of their treatment. She is then following up with the participants in 10 years’ time to see whether any changes in their breast density can be linked to whether they saw their breast cancer come back.

The current recommendation for women who have had ER‑positive breast cancer is to take hormone therapy for five years, but this can be raised to 10 years in cases where a woman has a high chance of her cancer returning. This project could provide a new method to predict which women would greatly benefit from continuing with their hormone therapy for longer. It will also allow doctors to identify women for whom the therapy is not effective at an early stage, and therefore find an alternative treatment that could help improve their chances of survival as soon as possible.