Key result
Second primary breast cancer is linked to ~35% higher overall mortality versus first primary cancer.
Why the study?
Prior studies suggesting inferior survival in second primary cancers did not account for prognostic factors such as comorbidity, obesity, smoking, and insurance status.
Does diagnosis of breast cancer as a second primary cancer compared to a first primary cancer affect mortality in women?
Does diagnosis of breast cancer as a second primary cancer compared to a first primary cancer affect mortality in women?
Overall and breast cancer-specific mortality are significantly higher when breast cancer is diagnosed as a second primary cancer compared to a first primary cancer, even after adjusting for prognostic factors.
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May warrant tailored surveillance for second primary breast cancer; challenges assumption of equivalent prognosis to first primaries.
Chao et al. (2026) studied this question. Breast cancer diagnosed as a second primary cancer is associated with higher overall (aHR 1.35) and breast cancer-specific mortality (aHR 1.27) compared to a first primary cancer.
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