Research on the cutoff tumor size of omitting radiotherapy for BCSS after breast conserving surgery in women aged 65 years or oder with low-risk invasive breast carcinoma: Results based on the SEER database

• Published in: Breast (Edinburgh) 2021-12, Vol.60, p.287-294
• Main Authors: Yang, Zejian, Li, Kunlong, Qiu, Pei, Ma, Yifei, Wang, Bin, Yan, Yu, Meng, Du, Feng, Chen, Ren, Yu, Li, Yijun, Li, Pingping, Zhou, Can
• Format: Article
• Language: English
• Subjects: Aged; Breast - pathology; Breast Neoplasms - pathology; Breast Neoplasms - radiotherapy; Breast Neoplasms - surgery; Breast-conserving surgery; Female; Humans; Mastectomy, Segmental; Neoplasm Staging; Original; Postoperative radiotherapy; Radiotherapy, Adjuvant; SEER; SEER Program; Tumor size; X-tile analysis
• ISSN: 0960-9776; 1532-3080
• DOI: 10.1016/j.breast.2021.11.015

Radiotherapy after breast-conserving surgery (BCS) is not always necessary in older women staged T1N0M0 with low-risk invasive breast cancer, but few studies have concluded the detailed tumor size as a reference for avoiding radiotherapy. The study was conducted to explore and identify the optimal cutoff tumor size. The study population was from the Surveillance, Epidemiology, and End Results (SEER) database in 2010–2016. Propensity score matching was used to balance the confounders between groups. Predictors associated with survival were analyzed by Kaplan–Meier, X-tile, Cox proportional hazards model and competing risk model. A total of 52049 women and 3846 deaths were included in the cohort with a median follow-up of 34 months. Based on the cutoff value determined by X-tile analysis, the study population were divided into small tumor group (≤14 mm in diameter) and large tumor group (>14 mm in diameter). Small tumors and radiotherapy were correlated with better breast cancer-specific survival (BCSS). In subgroup analysis, the absolute benefit of BCSS in 6 years attributed to radiotherapy was only 0.90% (RT vs. non- RT:98.77% vs. 97.87%) for patients with small tumors but up to 3.33% (RT vs. non- RT:97.10% vs. 93.77%) for those with large tumors. Small tumors and adjuvant radiotherapy were associated with improved long-term prognosis, and 14 mm in diameter was the cutoff tumor size of omitting radiotherapy for patients aged 65 or older with T1N0M0 stage, ER+ and HER2-breast carcinoma after BCS. [Display omitted] •Breast tumor size of 14 mm was the optimal cutoff predicting OS and BCSS.•Small tumors (≤14 mm) and radiotherapy were associated with improved OS and BCSS.•The benefit of radiotherapy was significant in patients with large tumors (>14 mm).•Radiotherapy could be omitted in elders with small low-risk breast tumor after BCS.