Risk factors for early recurrence in patients with hormone receptor-positive, HER2-negative breast cancer: a retrospective cohort study in Japan (WJOG15721B).

Background: Patients with early recurrence of hormone receptor (HR)-positive, HER2-negative (HR+/HER2-) breast cancer have a poor prognosis. We aimed to identify clinical and pathological risk factors for recurrence within three years after surgery of HR+/HER2- breast cancer.

Methods: We retrospectively reviewed clinical data of patients with stage II-III HR+/HER2- breast cancer who received adjuvant endocrine therapy from January 1, 2012 to January 1, 2017 at five institutions. Using univariable and multivariable analyses, we determined risk factors for invasive disease-free survival (IDFS). A nomogram was generated using variables from the multivariable analysis to predict 3-year IDFS rate.

Results: A total of 2732 patients were analyzed, with a median follow-up of 7.1 years. The 3-year IDFS rate was 92.1%. Multivariable analysis for IDFS revealed significant risk factors: age (40-69 vs. 20-39 years: HR 0.69, p = 0.011), nuclear grade (Grade 2 vs. Grade 1: HR 1.66, p < 0.001; Grade 3 vs. Grade 1: HR 1.64, p < 0.001), vascular invasion (Yes vs. No: HR 1.36, p = 0.027), pathological invasive tumor size (2-5 cm vs. < 2 cm: HR 1.75, p < 0.001; ≥ 5 cm vs. < 2 cm: HR 2.07, p < 0.001), number of positive lymph nodes (≥ 4 vs.0: HR 1.70, p < 0.001), and neoadjuvant chemotherapy (NAC) (Yes vs. No: HR 2.41, p < 0.001). The nomogram's concordance index was 0.68.

Conclusion: Younger age, nuclear grade, vascular invasion, tumor size and number of lymph node metastases were identified as independent risk factors for early recurrence. Patients whose physicians chose NAC had worse survival than those who did not.