Survival following radiotherapy in young women with localized early‐stage breast cancer according to molecular subtypes

• Published in: Cancer medicine (Malden, MA) Vol. 8; no. 6; pp. 2840 - 2857
• Main Authors: Liu, Qi‐Qi, Sun, He‐Fen, Yang, Xue‐Li, Chen, Meng‐Ting, Liu, Yang, Zhao, Yang, Zhao, Yuan‐Yuan, Jin, Wei
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.06.2019; John Wiley and Sons Inc; Wiley
• Subjects: Adult; Age; Biomarkers, Tumor; Breast cancer; Breast Neoplasms - diagnosis; Breast Neoplasms - epidemiology; Breast Neoplasms - mortality; Breast Neoplasms - radiotherapy; Cancer therapies; Chemotherapy; Clinical Cancer Research; Endocrine therapy; Epidemiology; Epidermal growth factor; ErbB-2 protein; Ethics; Female; Humans; Kaplan-Meier Estimate; Middle Aged; molecular subtype; Neoplasm Grading; Neoplasm Staging; Original Research; Patients; Prognosis; Radiation therapy; SEER Program; Studies; Surveillance; Survival; Treatment Outcome; Triple Negative Breast Neoplasms - genetics; Triple Negative Breast Neoplasms - mortality; Triple Negative Breast Neoplasms - pathology; Triple Negative Breast Neoplasms - radiotherapy; Young Adult; United States > US; breast cancer; molecular subtype; radiation therapy; survival
• ISSN: 2045-7634; 2045-7634
• DOI: 10.1002/cam4.2186

Background To evaluate the significance and benefit of radiotherapy (RT) in young early‐stage breast cancer patients according to different molecular subtypes. Methods We conducted a retrospective cohort study utilizing the Surveillance, Epidemiology, and End Results database with known hormone receptor (HoR) and human epidermal growth factor receptor 2 (HER2) status. Female patients aged 18‐45, received RT treatment, and diagnosed with stage T1‐3, N0‐3, M0 primary breast cancer between 2010 and 2013 were identified. Results Of all the 23 148 included patients, 14 708 (63.54%), 3385 (14.62%), 1225 (5.29%), and 3830 (16.55%) were diagnosed with luminal‐A (HoR + HER2‐), luminal‐B (HoR + HER2+), HER2‐enriched (HoR‐HER2+), and triple‐negative (HoR‐HER2‐) breast cancer, respectively. RT was significantly correlated with improved overall survival (OS, HR: 0.295; 95% CI:0.138‐0.63, P = 0.002) and breast cancer‐specific survival (BCSS, HR: 0.328; 95% CI: 0.153‐0.702, P = 0.004) in HER2‐enriched patients. In addition, a significantly prolonged OS was also observed when RT was given to luminal‐A (HR: 0.696; 95% CI: 0.538‐0.902, P = 0.006) and luminal‐B (HR: 0.385; 95% CI:0.199‐0.744, P = 0.005) breast cancer patients compared to those without RT. Multivariable‐adjusted analyses showed that HER2 was a significant favorable factor for RT benefit in breast cancer patients. Conclusions RT could offer significant survival benefit in luminal‐A, luminal‐B, and especially HER2‐enriched young early‐stage breast cancer female patients. The results enabled clinicians to predict the benefits of RT and improve evidence‐based treatment for breast cancer patients. RT offer significant OS benefit in luminal‐A, luminal‐B and especially HER2‐enriched breast cancer patients. HER2 was significant a favorable factor for RT benefit in breast cancer patients.