| Abstract |
Background: Breast cancer is an important cause of death among women. One way of classifying different
forms of breast cancer is by molecular features, usually in terms of the four subtypes: luminal A, luminal
B, HER2-enriched, and triple negative. Objectives: This study aimed to investigate the association between
molecular subtypes and survival among breast cancer patients treated with radiotherapy. Materials and Methods:
A retrospective cohort study was conducted. The subjects were 272 breast cancer patients who had received
treatment in the radiotherapy unit at Srinagarind Hospital, Thailand, between 1 January, 1999, and 31 May,
2009. The end of the study was 1 June, 2014. Overall survival was defined as the time elapsing between initial
registration at the radiotherapy unit and death or the end of the study. Survival curves were estimated by the
Kaplan-Meier method, and a multivariate analysis was performed using Cox’s proportional hazard regression
model. Results: The patient mean age was 47.5±10.4 at the time of diagnosis. Of the 272 patients, 146 (53.7%)
were classified as luminal A, 12 (4.4%) as luminal B, 30 (11.0%) as HER2-enriched, and 84 (30.9%) as triple
negative. The overall survival rates at 1, 3 and 5 years were 87.1%, 68.4% and 59.2%, respectively. According to
molecular subtypes, HER2-enriched patients had the lowest 5-year survival rate (30.0 %, 95%CI: 15.02-46.55).
The median follow-up time was 8.37 years. In the Cox model analysis a higher risk of death was found for patients
with HER2-enriched (HRadj=3.34, 95%CI:1.96-5.67), triple negative (HRadj=2.17, 95%CI: 1.44-3.27), and stage
IIlB (HRadj=2.20, 95%CI: 1.16-4.17) cancers. Conclusions: The worst survival rates were among patients classified
as HER2-enriched, triple negative and at stage IIIB. Early detection and an advanced treatment modality are
needed to help these patients. |
Publication
Journal Publication
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