Treatment Patterns Among Women Diagnosed With Stage I-III Triple-negative Breast Cancer

To examine contemporary treatment patterns for women diagnosed with stage I-III triple-negative breast cancer (TNBC) in the United States.

We identified 48,961 patients diagnosed with stage I-III TNBC from 2010 to 2013 in the National Cancer Data Base and created 3 treatment subcohorts (definitive locoregional therapy [appropriate local therapy, including surgery/radiation], adjuvant chemotherapy [stage II-III disease or stage I tumors with tumor size ≥1 cm], and adjuvant chemotherapy for small tumors [stage I tumors with tumor size <1 cm and node negative]). We performed descriptive analyses, calculated percentages for treatment receipt, and used multivariable modified Poisson regression models to estimate risk ratios (RRs) with 95% confidence intervals (CIs) predicting receipt of treatments.

Older age, larger tumor size, positive nodal status, and Southern/Pacific US regions, but not race/ethnicity, were strongly associated with a lower probability of receiving definitive locoregional therapy. Older age was also strongly associated with lower likelihood of adjuvant chemotherapy receipt, as were grade, negative nodal status, and higher comorbidity. For example, compared with women aged 18 to 39 years, those aged 75 to 90 years were 17% less likely to receive definitive locoregional therapy (RR, 0.83; 95% CI, 0.73-0.88), and 62% less likely to receive adjuvant chemotherapy (RR, 0.38; 95% CI, 0.35-0.41). Age, tumor grade, tumor size, and comorbidity score were also independently associated with receipt of chemotherapy for women with small TNBC.

Advancing age but not race/ethnicity was associated with lower likelihood of recommended treatment receipt among women with TNBC. Although omission of therapy among older patients with breast cancer may be appropriate in the case of smaller and lower risk TNBC, some were likely undertreated.