Results from a study presented at the virtual 2021 ASCO Annual Meeting show substantial variation in treatment selection and costs for first-line treatment of patients with metastatic breast cancer in Washington State.

“Evidence-based, national guidelines for the management of metastatic breast cancer (MBC) recommend numerous treatment options that do not capture the nuances of real-world practice,” explained Poorni Manohar, MD, University of Washington, Fred Hutchinson Cancer Research Center, Seattle, and colleagues.

“Disparities may exist across Washington State with financial implications for patients and health systems,” they continued.

This study aimed to assess real-world practice patterns for ER+/HER2- metastatic breast cancer.

Enrollment and insurance claims records were linked with Washington State cancer registries from 2008-2017 through collaboration with the Hutchinson Institute for Cancer Outcomes Research. The study cohost included women 18 years or older with de novo ER+/HER2- metastatic breast cancer in one of four payers: Premera, Regence, Medicare, or Medicaid.

First-line treatment was categorized as CDK4/6 inhibitors plus endocrine therapy, chemotherapy, or endocrine therapy alone. Fisher’s and Kruskal-Wallis testes were used to examine factors influencing treatment selection. Total costs were estimated for patients and payers.

A total of 140 patients were identified and included in the study. Median patient age was 64 (range 28-95). Majority of patients were Caucasian (90%). Based on Rural Urban Commuting Area classification, most patients lived in metropolitan neighborhoods (96%). More than 20% of patients lived in areas of high deprivation.

Patients had either commercial insurance (40.7%), Medicaid/Medicare (43.6%), or multiple forms of insurance (15.7%). For first-line treatment, 17 (12%) patients received first line therapy with CDK4/6 inhibitors plus endocrine therapy, 64 patients (46%) with chemotherapy, and 59 patients (42%) with endocrine therapy alone.

The study found the factors influencing treatment selection included age, comorbidity, score, and payer type. Older patients were more likely to receive endocrine therapy (30%) compared with chemotherapy (5%) or CDK4/6 inhibitors plus endocrine therapy (23%).

Of those who received CDK4/6 inhibitors plus endocrine therapy, over 50% had commercial insurance. Medicare patients were most likely to receive endocrine therapy alone.

For patients, the estimated mean cost of receiving first-line CDK4/6 inhibitors plus endocrine therapy was $20,368, chemotherapy was $10,624, and endocrine therapy alone was $13,292. For payers, these estimated mean costs were $175,932, $117,847, and $60,338, respectively.

“Our study shows substantial variation across Washington state in treatment selection and costs for patients with metastatic breast cancer in the first-line setting,” concluded Dr Manohar and colleagues.

“Our findings demonstrate the need for initiatives to standardize quality of care relative to clinical guidelines in metastatic breast cancer care,” they added.—Janelle Bradley