Young Age as a Predictor of Chemotherapy Recommendation and Treatment in Breast Cancer: A National Cancer Database...

Breast cancer, although the second most common malignancy in women in the United States, is rare in patients under the age of 40 y. However, this young patient population has high recurrence and mortality rates, with chemotherapy frequently used as adjuvant treatment. We aimed to determine whether age is an independent predictor of chemotherapy recommendation and subsequent treatment and the relationship to Oncotype Dx (ODX) recurrence score (RS).

The National Cancer Database was retrospectively reviewed from 2010-2016 to identify women with early-stage (pT1-pT3, pN0-pN1mic, M0), hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer who underwent ODX RS testing.

Of 95,382 patients who met the inclusion criteria, risk groups using the traditional ODX RS cutoffs were 59% low, 33% intermediate, and 8% high. Using Trial Assigning Individualized Options for Treatment RS cutoffs, risk groups were 23% low, 62% intermediate, and 15% high. Chemotherapy recommendation decreased as age at diagnosis increased (P < 0.001). Increasing age was associated with decreased odds of chemotherapy recommendation in univariate models both continuously (odds ratio: 0.98, 95% confidence interval 0.97-0.98; P < 0.001) and categorically by decade (P < 0.001). Age by decade remained an independent prognosticator of chemotherapy recommendation (P < 0.001), adjusted for risk groups.

Chemotherapy recommendation and treatment differs by age among patients with early-stage hormone receptor positive breast cancer who undergo ODX testing. While molecular profiling has been shown to accurately predict the benefit of chemotherapy, younger age at diagnosis is a risk factor for discordant use of ODX RS for treatment strategies in breast cancer; with patients aged 18-39 disproportionately affected.