ECCO2017: Could breast conservation be superior to mastectomy in early breast cancer patients?

A team from the Netherlands Comprehensive Cancer Organisation (Utrecht, The Netherlands) and the University of Twente and Mirelle Lagendijk (Rotterdam, The Netherlands) have studied the survival patterns of approximately 130,000 individuals with breast cancer. The results of the study indicate that patients with early stage cancers demonstrate a significant advantage for breast cancer therapy (BCT) – a breast conserving surgery combined with radiation therapy.

Previous research has indicated that there is an equal survival outcome for individuals who undergo mastectomy and BCT. However, these trials often exclude individuals with an existing disease. The equal survival outcomes have been challenged by other recent population-based studies that demonstrate a survival advantage for BCT; but these studies lack long-term follow-up and evaluated a limited number of patients.

In this study, differences in systemic treatments and prognostic factors (such as age, stage, comorbidity, hormonal receptor and HER2 status) were considered as possible explanations for the survival differences between mastectomy and BCT. They were also utilized to identify possible prognostic factors that may be able to predict if certain individuals would benefit more from BCT.

Sabine Siesling (Netherlands Comprehensive Cancer Organisation) commented: “We looked at two different groups in order to allow us to compare long-term outcomes in a more historical versus a more recent cohort, evaluating patients that had been able to benefit from more sophisticated diagnostics and therapies. A considerably superior survival, both specific to breast cancer and from any cause of death, was found for BCT in the early stage T1-2N0-1M0 cancers in both time cohorts.”

Analyzes of the cancers which showed no metastasis to distant organs, demonstrated a significant advantage for BCT in patients with increasing age, those with comorbidity and those who did not receive chemotherapy.

“Although this study is based on retrospective data with much detailed data, and residual confounding factors cannot be ruled out completely, we believe that this information will have potential to greatly improve shared treatment decision-making for future breast cancer patients in those aged over 50 years and those with comorbidity” reported Siesling.

Siesling concluded: “However, we would like to emphasize that these results do not mean that mastectomy is a bad choice. For patients for whom radiotherapy is not suitable or feasible due to social circumstances, for whom the risk of late side effects of radiotherapy is high, or who have the prospect of a poor aesthetic outcome following BCT, a mastectomy may still be the preferable treatment option. Our study showed that BCT is at least as good as mastectomy and that some patients might benefit more than others from BCT in the future.”

Source: ECCO 2017 press release