Stage I (T1N0M0) breast cancer with a median follow-up of 14 years: A retrospective cohort study of 328 consecutive patients and the prognostic value of tumor size, grade, and subtype

Abstract Purpose This study aimed to evaluate the long-term outcomes of stage I breast cancer(BC) patients diagnosed during the current era of screening mammography, immunohistochemistry receptor testing, and systemic adjuvant therapy. The primary endpoints were invasive disease-free survival (IDFS) and overall survival (OS). Methods A retrospective cohort study was conducted on 328 stage I BC patients treated consecutively in a single referral center with a follow-up period of at least 12 years. The STEEP system was used to define the endpoints. The influence of tumor size, grade, and subtype on the outcomes was analyzed. Results Most patients were treated by lumpectomy, sentinel node biopsy and adjuvant endocrine therapy and most (82%) were of subtype luminal-A. Only 24 patients underwent gene expression testing, which was introduced toward the end of the study period and 25.6% of our cohort received adjuvant chemotherapy. Mean invasive disease-free survival (IDFS) was 14.64 years, with a 15-year IDFS of 75.6%. Mean overall survival (OS) was 15.28 years with a 15-year OS of 74.9%. In a Cox multivariate analysis only tumor size (< 1 centimeter (cm) vs 1–2 cm), impacted significantly on IDFS. During follow-up, 20.1% of the cohort developed second primary cancers, including BC. Median time to diagnosis of a second BC was 6.49 years. Conclusion The study results emphasize the importance of long-term follow-up and screening for subsequent malignancies of patients with stage I BC and support the need for using prognostic and predictive indicators beyond the routine clinicopathological characteristics in luminal-A patients.