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Comment & Response
25, 2024

Clarification Regarding Breast Cancer Stage in France—Reply

Author Affiliations
  • 1Cancer Surveillance Branch, International Agency for Research on Cancer, Lyon, France
  • 2Department of Medical Oncology, Hospital Clinico San Carlos, IdISSC, Calle Profesor Martín Lagos, Madrid, Spain
  • 3Velindre Cancer Centre, Cardiff, Wales, United Kingdom
JAMA Oncol. Published online April 25, 2024. doi:10.1001/jamaoncol.2024.0671

In Reply We appreciate the thoughtful comments from Molinié et al regarding our recent publication on the global stage distribution of breast cancer at diagnosis.1 Their insights particularly about the staging of breast cancer in France provide an opportunity for further clarification and discussion.

Our study1 aimed to provide a comprehensive overview of the distribution of breast cancer stage at diagnosis worldwide. Yet we acknowledged important variations in stage recording and reporting across countries that are linked to the availability and use of multiple staging systems and their evolution, as well as recording practice, standards used, and completeness of data from sources that are available to population-based registries (PBCRs).2,3 The point raised regarding the classification of “advanced stage” breast cancer in France, which was based on the European Network of Cancer Registries (ENCR) guidelines on the condensed TNM for Coding Extent of Disease,4 encompassing both nonresected cancers without visceral metastasis and metastatic cancers, is an important aspect of such variation in standards used and practices in registries.1 The condensed TNM system was developed as a simplified staging system to allow PBCRs to overcome complexities in collecting stage information, yet, has not been considered widely by European registries who rather opt for the TNM system.5 The aim of our study was to understand the variation of proportions of metastatic breast cancer across countries, as such we prioritized studies that reported using TNM classification (stage IV or M1) or SEER (distant). In this article, we acknowledged that data from 2 countries (France and Poland) were only available based on a condensed TNM system that would group both metastatic and nonresectable tumors in the advanced stage category. It is imperative to note that our meta-analysis integrated data from various sources, each with their methodologies and categorizations. Although we endeavored to maintain consistency and accuracy, the heterogeneity of data is an inherent challenge in such large-scale analyses.1 Although highlighted in our original publication, we would like to emphasize that the condensed TNM classification mentioned by Molinié et al could indeed inflate the perceived distribution of metastatic breast cancer in France compared with other countries. However, it is crucial to emphasize that our analysis, despite these limitations, provides valuable insights into the global patterns of breast cancer diagnosis. These findings have significant implications for public health policies, resource allocation, and awareness campaigns.1

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