Trends in surgery and adjuvant treatment for early-stage breast cancer: a population-based study in Queensland, Australia.

Purpose: Our aim was to describe variations in the treatment of early-stage breast cancer and to examine factors associated with disease-specific survival (DSS).

Methods: The study used linked data for 24,190 women with a T1 (≤ 20 mm) breast cancer who underwent surgery from 2005 to 2019. Multivariate logistic regression was used to model predictors of receiving breast-conserving surgery (BCS) compared to mastectomy and a multinomial model was used to examine factors associated with type(s) of treatment received.

Results: Overall, 70.3% had BCS, with a reduced likelihood of BCS observed for younger women (p < 0.001), rural residence, (p < 0.001), socioeconomic disadvantage (p = 0.004), higher tumour grade (p < 0.001) and surgery in a public versus private hospital (p < 0.001). Compared to women who received BCS and radiation therapy (RT), those having mastectomy alone or mastectomy plus RT were more likely to be younger (p < 0.001), live in a rural area (p < 0.001), have higher-grade tumours (p < 0.001) and positive lymph nodes (p < 0.001). Overall 5-year survival was 95.3% and breast cancer-specific survival was 98.3%. Highest survival was observed for women having BCS and RT and lowest for those having mastectomy and RT (p < 0.001).

Conclusion: Our results indicate some variation in the management of early-stage breast cancer. Lower rates of BCS were observed for rural and disadvantaged women and for those treated in a public or low-volume hospital. Whilst survival was high for this cohort, differences in tumour biology likely explain the differences in survival according to treatment type.