Collecting long-term outcomes in population-based cancer registry data: the case of breast cancer recurrence

Researchers from the International Agency for Research on Cancer (IARC) and partner institutions reviewed studies that used population-based cancer registry data, to determine the current availability of data related to cancer recurrence in women initially diagnosed with non-metastatic breast cancer. The authors provide recommendations to support the collection and reporting of data on recurrence in patients with breast cancer. The review article was published in the journal JCO Global Oncology.

The research team identified 23 studies from 11 registries in 8 countries spanning Europe, North America, and Oceania to include in the review. Most of the studies were retrospective and collected recurrence data only for ad hoc studies rather than as part of their routine registration. The median follow-up time for patients with breast cancer and survivors of breast cancer in the included studies ranged from 3.5 years to 14.8 years.

The researchers found differences in the proportions of metastatic recurrence, which ranged from 1.1% to 28.3%. The definitions and time frames used in the studies to categorize a cancer as recurrent varied greatly. Studies with higher proportions of recurrence tended to have longer follow-up times and/or to focus on higher-risk groups, such as younger age groups or women with triple-negative breast cancers. To date, no consented international guidelines for the routine collection of cancer recurrence data exist, and the actual prevalence of metastatic breast cancer, including metastatic recurrence, remains largely unknown.

The researchers found that most population-based databases, such as cancer registries, do not routinely capture or collect data on long-term outcomes of patients with cancer, because of the resources that this active follow-up requires. By examining the methods and resources used by the population-based cancer registries that have collected recurrence information, the research team assessed how this has been done, to inform about how it can be achieved in the future.

The number of survivors of breast cancer is growing, but the number of women experiencing metastatic recurrence is unknown due to a lack of international guidelines for the registration and analysis of recurrence data and support for cancer registries to routinely collect this important data item. Considering that little is still understood about the impact of metastatic breast cancer (including recurrence) at the population level, the findings and recommendations of this study provide an important knowledge base to support cancer registries in the routine collection of recurrence data, to further the understanding of the impact of long-term outcomes of breast cancer.

Morgan E, O’Neill C, Bardot A, Walsh P, Woods R, Gonsalves L, et al.
Collecting long-term outcomes in population-based cancer registry data: the case of breast cancer recurrence
JCO Glob Oncol. Published online 31 October 2024;
https://doi.org/10.1200/GO-24-00249

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