Young-onset breast cancer: a poor prognosis only exists in low-risk patients.

The number of reported young breast cancer cases has increased dramatically recently. The impact of age on the outcomes of breast cancers remains controversial. Our study aimed to explore the factors that can stratify the impact of young age on the prognosis of early breast cancer patients. In total, 244,324 patients with early breast cancer in the Surveillance, Epidemiology, and End Results database were identified from 1990 to 2007. Survival curves were generated using the Kaplan-Meier method. The 5- and 10-year cancer-specific survival (CSS) rates were calculated using the Life-Table method. Multivariable analyses were used to identify prognosti c variables (without age) to construct the nomograms. The risk score developed from the nomogram was used to classify the cohort into three subgroups (low-, medium- and high-risk subgroup). Approximately 8.89% of women were diagnosed with breast cancer at a young age (≤ 40 years). Clinical nomogram had the potential ability to predict CSS accurately with a well C-index (0.785). Subgroup analysis indicated that the risk score as the sole factor can stratify the impact of young age on the prognosis of early breast cancer patients. Young breast cancer patients had a worse prognosis in the low-risk (HR=0.61; 95% CI: 0.57-0.65; P<0.001) or medium-risk subgroup (HR=0.89; 95% CI: 0.85-0.93; P<0.01) than in the high-risk subgroup (P=0.431). In conclusion, the worse prognosis of young women only appeared in the low- and medium-risk subgroups rather than in the high-risk subgroup. The risk score yielded from the nomogram model can assist clinical decision making for young breast cancer patients.