Clinical Research Papers:
Effect of tumor size on breast cancer-specific survival stratified by joint hormone receptor status in a SEER population-based study
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Yi-Zi Zheng1,2, Lei Wang1,2, Xin Hu1, Zhi-Ming Shao1,2,3
1Department of Breast Surgery, Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, Fudan University, Shanghai, China
2Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
3Institutes of Biomedical Science, Fudan University, Shanghai, China
Xin Hu, e-mail: [email protected]
Zhi-Ming Shao, e-mail: [email protected]
Keywords: breast cancer, hormone receptor status, tumor size, breast cancer-specific mortality
Received: March 06, 2015 Accepted: April 28, 2015 Published: May 11, 2015
Background & Aims: The prognostic value of tumor size is variable. We aimed to characterize the interaction between tumor size and hormone receptor (HoR) status to determine breast cancer-specific mortality (BCSM).
Methods: We used the Surveillance, Epidemiology and End Results (SEER) registry to identify 328, 870 female patients diagnosed with invasive breast cancer from 1990 through 2010. Primary study variables included tumor size, joint HoR status and their corresponding relationship. Kaplan-Meier and adjusted Cox proportional hazards models with interaction terms were utilized.
Results: The multivariable analysis revealed a significant interaction between tumor size and HoR status (P < 0.001). Using tumors 61–70 mm in size as the reference for estrogen receptor-negative (ER−) and progesterone receptor-negative (PR−) disease, the hazard ratio (HR) for BCSM increased with increasing tumor size across nearly all categories. In the ER-positive (ER+) and PR-positive (PR+) group, however, patients with tumors > 50 mm had nearly identical BCSM rates (P = 0.127, P = 0.099 and P = 0.370 for 51–60 mm, 71–80 mm and > 80 mm tumors, respectively), whereas BCSM was positively correlated with tumors < 51 mm.
Conclusions: The observation of identical HRs for BCSM among patients with ER+ and PR+ tumors >50 mm underscores the importance of individualized treatment. Our findings may contribute to a better understanding of breast cancer biology.
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