Listen to HER2: Why Are So Many Women Missing Out on Trastuzumab?

Medical guidelines say most women with HER2-positive breast cancer should receive trastuzumab. But not everyone who should take trastuzumab actually does take it. Last year LBBC covered a study that suggested less than half of women on Medicare with early-stage HER2-positive breast cancer actually took trastuzumab within a year of diagnosis. The study also suggested that black women were less likely to receive trastuzumab than white women.

For LBBC's Listen to HER2 program, Trevor A. Jolly, MBBS,  a member of the breast cancer and geriatric oncology groups at UNC Chapel Hill with knowledge of the study, tells us why trastuzumab is so important, what the study found about who is, and isn’t, getting treatment with trastuzumab, and what can be done about it.

Trastuzumab (Herceptin) was approved by the US Food and Drug Administration for treatment of patients with metastatic HER2-positive breast cancer in 1998 and treatment of early-stage HER2-positive breast cancer in 2006. It effectively binds to the HER2 receptor, stops cancer cells from multiplying, and results in cancer cell death. Studies have consistently shown that trastuzumab reduces the risk of breast cancer recurrence by about 50 percent and improves survival by about 30 percent. Recommendations for trastuzumab-based post-surgery chemotherapy are included in the American Society for Clinical Oncology and the National Comprehensive Cancer Network national guidelines. This type of treatment is considered by most in the field to be the standard of care.

Given such improvement in the outcomes of HER2-positive breast cancer patients receiving trastuzumab, you would expect that all appropriate patients with HER2-positive breast cancer would receive trastuzumab-based post-surgery chemotherapy.

But research suggests that this is not necessarily true. Interestingly, when the author of the study “Disparities in Use of Human Epidermal Growth Hormone Receptor 2-Targeted Therapy for Early-Stage Breast Cancer” explored the pattern of trastuzumab use among women on Medicare, they found that overall, 50 percent of white women and 40 percent of black women with HER2-positive breast cancer received some trastuzumab therapy within 1 year of diagnosis.

The authors explored trastuzumab use among those with locally advanced, stage III breast cancer. Here, they found that 74 percent of white women and 56 percent of black women received trastuzumab. After adjusting for issues like age, tumor characteristics, poverty and other health conditions study participants had, the researchers found that black women were 25 percent less likely than similar white women to receive trastuzumab within 1 year of diagnosis.

So, what do these data imply? First it is important to point out that this study has several limitations. For example, the study is not able to determine if women didn’t receive trastuzumab because it was not offered by their doctors, or if it was offered and declined by the patient, and the reasons for these decisions. It is important to note that trastuzumab is used with chemotherapy. It is possible that at least some women didn’t receive trastuzumab because of frailty or other issues that didn’t make them good candidates for chemotherapy use. Also, the Medicare population is largely made up of those 65 and older. While some studies have shown that in general older women are less likely to be offered chemotherapy, others have suggested that such patients may have treatment preferences which favor quality of life over length of life, which could influence treatment preference and their decision not to receive trastuzumab. Indeed, the fact that 26 percent of white women with locally advanced, stage III disease in this study did not receive trastuzumab should not go unnoticed and suggests that other factors besides race may be involved in the decision-making process.

Despite these limitations, if these findings are confirmed by research studies of patients, and providers in the clinic, it should come as no surprise. Studies have consistently shown racial disparities among black women in a variety of cancerous and non-cancerous conditions. The authors of this study speculate about factors that may serve as barriers to receiving trastuzumab, contributing to treatment disparities. This could include financial and social factors, and factors related to how providers and patients interact in the clinic.

This study received a lot of press when it was released last year because it was one of the first to document such disparities among women with HER2-positive breast cancer. What’s important now is that our leaders have the will to act to reverse such known racial inequities in healthcare and in the broader society that allows such disparities to persist. This is not something that can be solely addressed at an individual level. System and policy changes are required.

Trevor A. Jolly, MBBS is a member of the breast cancer and geriatric oncology groups at UNC Chapel Hill. Read more Listen to HER2 stories here.

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