Scientists have found that testing for a biomarker of the oestrogen receptor protein helps with prognosis in pre-invasive breast cancer.
This biomarker is routinely tested in patients with invasive breast cancer as part of the process of predicting long-term outcomes and deciding on treatment. The value of testing it for ductal carcinoma in situ was unclear.
So, Dr Mangesh Thorat of Queen Mary University of London, UK, carried out a trial to investigate.
They tested tissue samples from 181 patients with recurrent breast cancer and compared them to 362 similar people without breast cancer. This showed oestrogen receptor expression patterns were indicative of the patient’s risk level.
The study was published in Clinical Cancer Research yesterday (16 March).
"Oestrogen receptor expression is a strong prognostic factor with greater than three-fold risk of ipsilateral recurrence in oestrogen receptor-negative ductal carcinoma in situ," they write.
"Oestrogen receptor-positive ductal carcinoma in situ with distinct oestrogen receptor-negative clones has a recurrence risk similar to oestrogen receptor-negative ductal carcinoma in situ."
They conclude: "Oestrogen receptor protein should be routinely assessed in ductal carcinoma in situ and oestrogen receptor scoring should take clonality of expression into account."
Dr Thorat says: “It is unlikely that such a study could currently be reproduced elsewhere in the world, and the robustness of these results means we can rely on them to make changes to clinical practice.
"Routine testing of oestrogen receptor protein will help to avoid both overtreatment and undertreatment in this type of breast cancer. The insights from this study will also help improve future breast cancer research through use of new scientific models, particularly in areas of drug resistance and the use of targeted therapies.”
Thorat, M. A. et al. Prognostic value of ER and PgR expression and the impact of multi-clonal expression for recurrence in ductal carcinoma in situ: Results from the UK/ANZ DCIS trial. Clinical Cancer Research 16 March 2021; doi: 10.1158/1078-0432.CCR-20-4635
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