Abstract
Background
Earlier randomised control trials illustrate equal survival outcomes after breast conserving surgery plus radiotherapy (BCS+RT) and mastectomy (MTX) in women with early stage breast cancer (ESBC) whereas more recent observational studies suggest BCS+RT is better or at least equal to MTX.
Aims:
To compare breast cancer specific mortality and overall mortality after BCS, BCS+RT, MTX and MTX+RT in New Zealand women with early stage breast cancer.
Methods
This population-based study involves all women who were diagnosed with ESBC (Stage I-IIb) in the four health regions between 1st January 2000 and 30th June 2014 and had undergone one of: BCS, BCS+RT, MTX or MTX+RT as their primary treatment. Kaplan Meier estimator and Cox proportional hazard modelling were used to compare hazards of breast cancer specific and overall mortality across the four types of surgical treatment, and demographic, clinical and systemic treatment factors were adjusted.
Results
10,289 women were analysed: 5154 (50.1%) received BCS+RT, 1042 (10.1%) BCS, 3069 (29.8%) MTX and 1024 (10.0%) MTX+RT.
Compared to women who received BCS+RT, those who received other types of surgical treatment had a higher DSS risk (adjusted HR: 1.78 (95%CI: 1.47-2.14) for BCS; 1.49 (95%CI: 1.20-1.83) for MTX; 1.50 (95% CI: 1.16-1.94) for MTX+RT) as well as OS (adjusted HR: 1.47 (95% CI: 1.47-2.14) for BCS; 1.59 (95% CI: 1.38-1.83) for MTX; 1.49 (95% CI: 1.22-1.82) for MTX+RT.
Conclusion
BCS+RT is associated with better survival outcomes in New Zealand women with early breast cancer. The findings could be assessed in future randomised trials.