Background: The benefit of pathologic complete response (pCR) in early breast cancer (eBC) is not well described in the real-world setting. This study used the nationwide Flatiron Health electronic health record-derived deidentified database to describe treatment patterns and survival outcomes by pCR status after neoadjuvant therapy (NAT) in women with triple-negative or HR+/HER2- eBC. Materials & methods: Observational cohort study analyzing women with eBC who started NAT between 2011 and 2018. Results: 496 women were included in the study; of those, 16.1% achieved pCR, of which 35.7% were triple-negative and 6.1% were HR+/HER2- eBC. More women with triple-negative eBC (95.2%) were exclusively treated with chemotherapy-based NAT versus HR+/HER2- eBC (56.1%). In multivariate analyses from NAT start, not achieving pCR was associated with increased risk of death and progression. Conclusion: pCR status may be a reliable prognostic indicator for survival in these eBC subtypes in the real-world setting.
Keywords: Flatiron Health; HER2-negative; HR-positive; early breast cancer; pathologic complete response; real-world; triple-negative.
Response to treatment before surgery indicates better outcomes in breast cancer patients. To understand how well cancer treatments work, patients are compared on their overall survival. This measures the number of people in a study or treatment group who are still alive after a certain amount of time from when they were diagnosed or started treatment. Overall survival shows how well patients are doing in their cancer journey, but it takes time to understand how good treatments are when using this measure. In women with early-stage breast cancer, a quicker way to understand how well patients react to their treatment is called pathologic complete response (pCR). Some people have whole-body treatments such as chemotherapy before surgery (known as neoadjuvant treatment). For these patients, pCR may occur after neoadjuvant treatment, meaning all signs of cancer are gone when they have surgery. In real-life clinical settings, little research has been done to understand how pCR can measure breast cancer survival. In this study, the authors investigate whether women who had a pCR were more or less likely to have their cancer become worse or experience death than those who did not achieve pCR. The health records of 496 women diagnosed with early breast cancer over an eight-year period were assessed. The results show that women who did not have a pCR were more likely to have their cancer become worse or die. This means that pCR could be a better way than overall survival to identify which treatments work well in early breast cancer, and importantly, change the course of a patient's journey.