Radiotherapy after breast conserving surgery reduces the risk of the disease returning to the same breast over the following ten years but does not improve overall survival rates long term, a conference will hear today.
Clinicians behind the one of the longest and most up-to-date follow-ups of randomised controlled clinical trials of breast conserving therapy say their findings provide important information for long-term survivors of breast cancer.
Professor Ian Kunkler, honorary professor of clinical oncology at the University of Edinburgh, UK, today presented results from the Scottish breast conservation trial to the 13th European Breast Cancer Conference, in Barcelona, Spain.
It followed 585 women aged 70 or younger for 30 years who were diagnosed with early breast cancer.
They were all treated with breast conserving surgery followed by systemic therapy, such as chemotherapy or tamoxifen, and were randomised to either receive or not to receive radiotherapy after surgery.
Ten years after radiotherapy, there was more than a 60% reduction in locoregional recurrence in the women who had been randomised to receive radiotherapy compared to those who had not.
After ten years, the annual risk of a recurrence was similar in both groups, as was overall survival. After 30 years, 24% of women who had radiotherapy were still alive compared to 27.5% of those who did not.
Prof Kunkler said: “We found that there is no long-term improvement in overall survival for those women having radiotherapy. This may be because, although radiotherapy may help to prevent some breast cancer deaths, it may also cause a few more deaths, particularly a long time after the radiotherapy, from other causes such as heart and blood vessel diseases.
“The benefits of having radiotherapy in terms of fewer local recurrences are only accrued over the first ten years after radiotherapy; thereafter, the rate of local recurrence is similar whether or not patients had radiotherapy.”
The conference also heard from Dr Federica Miglietta, whose study has shown patients with HER-2 positive breast cancer are less likely to survive if their initial treatment fails to eradicate the tumour completely and they have high levels of tumour infiltrating lymphocytes (TILs) in the residual disease.
Dr Miglietta, of the University of Padua and a medical oncologist at the Istituto Oncologico Veneto, said for HER-2 cancer, post-treatment TILs seemed to be counter-productive if any disease remained after patients had received chemotherapy and neoadjuvant treatment.
Dr Miglietta and her colleagues examined data from 295 HER2-positive breast cancer patients who had been treated at three Italian centres between 2001 and 2021.
Of those, 195 (60%) had residual disease after neoadjuvant treatment. Information on the residual cancer burden and TILs in the residual tumours was available for 180 and 159 patients, respectively.
They found 68% of patients with high levels of TILs in their residual disease were alive after five years compared to 84% of patients with low levels of TILs.
These findings applied only to HER2-positive breast cancer and not to other types of breast cancer.
Abstract no: 2. Randomised controlled trial of breast conserving therapy: 30-year analysis of the Scottish breast conservation trial.
Abstract no: 4. A composite prognostic model for overall survival (OS) based on residual cancer burden (RCB) and tumor-infiltrating lymphocytes (TILs) on residual disease (RCB+TIL) in HER2+ breast cancer patients treated with neoadjuvant therapy: a multicenter study.
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