ECCO 2017: Some Patients With Early-Stage Breast Cancer May Benefit More From Breast-Conserving Therapy Than Mastectomy
Breast-conserving therapy (breast-conserving surgery combined with radiation therapy) may be superior to mastectomy in certain patients with breast cancer, according to results from the largest study on this topic to date, presented at the 2017 European Cancer Congress (Abstract 4LBA).
Although randomized trials initiated in the 1980s have shown equal survival outcomes for breast-conserving therapy and mastectomy, trials often exclude elderly patients or patients with comorbidities. Studies with large, population-based groups, including those with comorbidities and those who are elderly, can add to the knowledge based on these trials and provide outcome that is more widely applicable and reflect daily practice. Several recent population-based studies showed a survival advantage for breast-conserving therapy. However, these studies tended to lack long-term follow-up, evaluated limited patient numbers, had differences in medication after surgery between both groups, and lacked the data on cause of death that are needed to evaluate breast cancer–specific survival. All this could have led to the introduction of confounding factors, such as severity of disease or death due to other causes, the researchers say.
In the current study, Sabine Siesling, PhD, from the Netherlands Comprehensive Cancer Organisation (IKNL) and the University of Twente, and Mirelle Lagendijk, MD, from the Department of Surgical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands, and colleagues from other hospitals, studied survival nationwide in nearly 130,000 breast cancer patients, divided into two groups: those diagnosed between 1999–2005 and those diagnosed between 2006–2012. The patients selected from the Netherlands Cancer Registry had no metastases. To obtain information on cause of death, data were linked to the cause of death register.
A number of prognostic factors such as age, stage, comorbidity, hormonal receptor and HER2 status, and differences in systemic treatments were included and considered as possible explanations for the previously reported survival differences between breast-conserving therapy and mastectomy. This enabled the identification of possible prognostic factors that might, in the future, predict which patients could benefit most from breast-conserving therapy.
Study Findings
“We looked at two different groups in order to allow us to compare long-term outcomes in a more historical vs 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 breast-conserving therapy in the early-stage T1-2N0-1M0 cancers in both time cohorts,” said Dr. Siesling.
To identify patients who could possibly benefit most from breast-conserving therapy, both time cohorts were divided into subgroups. Evaluation of T1-2N0-1M0 cancers, which are at a stage when metastasis to distant organs has not yet occurred, in both groups showed a considerable advantage for breast-conserving therapy 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 in [patients with breast cancer] aged over 50 years and those with comorbidity,” said Dr. Siesling.
“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 breast-conserving therapy, a mastectomy may still be the preferable treatment option. Our study showed that breast-conserving therapy is at least as good as mastectomy, and that some patients might benefit more than others from breast-conserving therapy in the future,” Dr. Siesling concluded.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
