Background: The recently developed MDACC nomogram purports to predict the risk of bone-only metastasis in women with early breast carcinoma based on five clinical and pathological characteristics. We set out to externally validate and assess its robustness using a tertiary breast cancer centre database.
Methods: All consecutive women treated for early breast cancer in our centre between January 1989 and December 2013 and who had all the nomogram variables documented were eligible for analysis.
Results: We identified 1255 eligible women for external validation analysis. The median follow-up was 54 months (range: 1-312) and time to initial metastasis 20 months (range: 1-80). The correspondence between the actual bone-only metastasis and the nomogram predictions implied poor calibration of the nomogram in the validation cohort, be it in the whole cohort or when stratified by breast cancer subtype.
Conclusion: This external validation study of the MDACC nomogram showed limitations in its generalizability to a new and independent European patient population.
Keywords: Bone metastases; Breast cancer; Molecular subtype; Nomogram.
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