Influence of age as a continuous variable on the prognosis of patients with pT1-2N1 breast cancer

• Published in: Breast (Edinburgh) Vol. 66; pp. 136 - 144
• Main Authors: Zhao, Xu-Ran, Tang, Yu, Wu, Hong-Fen, Guo, Qi-Shuai, Zhang, Yu-Jing, Shi, Mei, Cheng, Jing, Wang, Hong-Mei, Liu, Min, Ma, Chang-Ying, Wen, Ge, Wang, Xiao-hu, Fang, Hui, Jing, Hao, Song, Yong-Wen, Jin, Jing, Liu, Yue-Ping, Chen, Bo, Qi, Shu-Nan, Li, Ning, Tang, Yuan, Lu, Ning-Ning, Zhang, Na, Li, Ye-Xiong, Wang, Shu-Lian
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.12.2022; Elsevier
• Subjects: 1–3 positive lymph nodes; Age; Breast neoplasm; Breast Neoplasms - surgery; Female; Humans; Mastectomy; Middle Aged; Neoplasm Recurrence, Local - pathology; Neoplasm Staging; Original; Prognosis; Radiotherapy; Radiotherapy, Adjuvant; Retrospective Studies; RT; and End Results; P-splines; OS; HR; Radiotherapy; LRR; 1–3 positive lymph nodes; DFS; Surveillance; Mastectomy; PMRT; HER2; Age; LVI; Breast neoplasm
• ISSN: 0960-9776; 1532-3080
• DOI: 10.1016/j.breast.2022.08.005

To assess the influence of age as a continuous variable on the prognosis of pT1-2N1 breast cancer and examine its decision-making value for postmastectomy radiotherapy (PMRT). We retrospectively evaluated 5438 patients with pT1-2N1 breast cancer after mastectomy in 11 hospitals. A multivariable Cox proportional hazards regression model with penalized splines was used to examine the relationship between age and oncologic outcomes. The median follow-up was 67.0 months. After adjustments for confounding characteristics, nonsignificant downward trend in locoregional recurrence (LRR) risk was observed with increasing age (P-non-linear association = 0.640; P-linear association = 0.078). A significant non-linear association was found between age and disease-free survival (DFS) and overall survival (OS) (P-non-linear association <0.05; P-linear association >0.05, respectively). The DFS and OS exhibited U-shaped relationships, with the hazard ratios (HRs), reaching a nadir at 50 years old. A decreased risk of LRR with PMRT vs. no PMRT (HR = 0.304, 95% CI: 0.204–0.454) was maintained in all ages. The HR of PMRT vs. no PMRT for DFS and OS gradually increased with age. In patients ≤50 years old, PMRT was independently associated with favorable LRR, DFS, and OS, all P < 0.05). In patients >50 years old, PMRT was independently associated with reduced LRR (P = 0.004), but had no effect on DFS or OS. Age was an independent prognostic factor for pT1-2N1 breast cancer; PMRT provided survival benefits for patients ≤50 years old, but not for patients >50 years old. •The LRR risk showed a downward trend with increasing age in pT1-2N1 breast cancer.•Age showed a U-shaped association with DFS and OS, with 50 years being a reference.•The HR of PMRT vs. no PMRT on LRR remained almost constant in all ages.•The HR of PMRT vs. no PMRT for DFS and OS gradually increased with age.•PMRT provided significant survival benefits for patients ≤50 years old.