Low Lifetime Risk of Contralateral Breast Cancer in a Middle-Income Asian Country: Evidence to Guide Post-treatment...

Area of Science:

• Oncology
• Epidemiology
• Surgical Oncology

Background:

• Contralateral risk-reducing mastectomy (CRRM) rates are rising in Western countries, despite controversial survival benefits.
• Uptake of CRRM in Asia is currently low but may increase, necessitating evidence for clinical decision-making.
• This study addresses the need for data on contralateral breast cancer (CBC) risk in an Asian population.

Purpose of the Study:

• To determine the incidence and cumulative risk of contralateral breast cancer (CBC) in early-stage breast cancer patients in Southeast Asia.
• To identify independent predictors associated with the development of CBC in this population.

Main Methods:

• Retrospective cohort study of 2937 patients with stage I and II breast cancer diagnosed between 1993-2012.
• Multinomial logistic regression analysis was employed, accounting for competing risks of death.
• Predictors analyzed included age at diagnosis, ethnicity, family history, TNM stage, and treatment modalities.

Main Results:

• Over a median follow-up of 6 years, 50 women developed CBC.
• The 5-year cumulative risk of CBC was 1.0% (95% CI 0.6-1.4%), and the 10-year risk was 2.8% (95% CI 2.0-3.6%).
• Independent predictors for CBC included young age at diagnosis, positive family history of breast cancer, and stage I disease.

Conclusions:

• The risk of developing contralateral breast cancer (CBC) is notably low in the Southeast Asian population studied.
• Clinical recommendations and patient counseling regarding contralateral risk-reducing mastectomy (CRRM) should be approached with caution, considering the low CBC risk.