105P Real-world systemic treatment choices and survival outcomes of patients diagnosed with non-metastatic high-risk HR+/HER2- breast cancer in the Netherlands

Abstract

This study determines the proportion of patients with high-risk hormone receptor-positive human epidermal growth factor receptor-2-negative (HR+/HER2-) breast cancer (BC) within the total cohort of patients with non-metastatic HR+/HER2- BC and compares their systemic treatments and survival rates with those of patients with low- and intermediate-risk HR+/HER2- BC and triple-negative (TN) BC. All women (≥18 years) diagnosed with non-metastatic invasive HR+/HER2- BC or TNBC in the Netherlands between 2011 and 2019 were identified from the Netherlands Cancer Registry. Patients with HR+/HER2- BC were classified as low-, intermediate-, or high-risk, based on the number of positive lymph nodes, tumour size, and histological grade. Overall survival (OS) was evaluated using Kaplan-Meier survival analyses. Relative survival (RS) was estimated with the Pohar Perme method and defined as the ratio between OS and the expected survival of the Dutch population, using data from Statistics Netherlands. Survival data were available up to January 31, 2022. This study included 86,522 patients with HR+/HER2- BC. Of these, 51% had low-risk, 32% had intermediate-risk, and 13% had high-risk disease. In 4% of patients, the risk profile could not be defined. Endocrine therapy and chemotherapy use increased with an increasing risk classification: from 38% and 7% in low-risk, and 90% and 47% in intermediate-risk patients to 94% and 73% in high-risk patients. The 10-year OS and RS (95% confidence interval) were 84.2% (83.6-84.7) and 97.7% (96.8-98.4) in low-risk, 75.4% (74.5-76.2) and 92.4% (90.9-93.6) in intermediate-risk, and 64.4% (63.0-65.7) and 72.6% (70.8-74.3) in high-risk patients. The 10-year OS and RS of 12,448 patients with TNBC were 70.5% (69.4-71.6) and 78.3% (76.7-79.8), respectively. This study shows that 13% of patients with non-metastatic HR+/HER2- BC had high-risk disease. Although the majority of these patients received endocrine therapy and chemotherapy, the 10-year OS and RS rates were low and even worse than those of patients with TNBC. These data indicate an unmet medical need for modification of systemic treatment in this subgroup of patients.