- Breast cancer survivors may face elevated risk for second primary malignancy (SPM), which is associated with poorer prognosis and may be driven by chemotherapy exposure.
Why this matters
- Findings suggest the need for more screening for SPM among breast cancer survivors.
- Retrospective cohort of 442,234 stage I-III breast cancer survivors (2000-20014).
- Analysis compared breast cancer survivors with the general population through Standardized Incidence Rates (SIRs).
- Funding: Source not disclosed.
- The overall incidence of SPM for all sites was 15% greater in breast cancer survivors than in the general population (SIR, 1.15; 95% CI, 1.14-1.16).
- The most common SPMs were breast (33.4%), digestive system (16.9%), lung and bronchus (13.4%), genital system (10.4%), lymphatic and hematopoietic system (7.6%), urinary system (5.1%), and thyroid (3.3%).
- Developing SPM (vs breast cancer with no SPM) was associated with worse breast cancer-specific survival and worse OS (both P<.001>
- Chemotherapy exposure was associated with higher incidences of SPM for all sites except lymphoma (SIR, 0.80; 95% CI 0.72-0.88), myeloma (SIR, 0.85; 95% CI 0.71-1.01), and chronic lymphocytic leukemia (SIR, 0.57; 95% CI 0.43-0.74).
- Retrospective observational design.
- Lack of detail on chemotherapy type.