Abstract
PurposeFollow-up after breast cancer treatment aims for an early detection of locoregional breast cancer recurrences (LRR) to improve the patients’ outcome. By estimating individual’s 5-year recurrence-risks, the Dutch INFLUENCE-nomogram can assist health professionals and patients in developing personalized risk-based follow-up pathways. The objective of this study is to validate the prediction tool on non-Dutch patients.Material and methodsData for this external validation derive from a large clinical cancer registry in southern Germany, covering a population of 1.1 million. Patients with curative resection of early-stage breast cancer, diagnosed between 2000 and 2012, were included in the analysis (n = 6520). For each of them, an individual LRR-risk was estimated by the INFLUENCE-nomogram. Its predictive ability was tested by comparing estimated and observed LRR-probabilities using the Hosmer–Lemeshow goodness-of-fit test and C-statistics.ResultsIn the German validation-cohort, 2.8% of the patients developed an LRR within 5 years after primary surgery (n = 184). While the INFLUENCE-nomogram generally underestimates the actual LRR-risk of the German patients (p < 0.001), its discriminative ability is comparable to the one observed in the original Dutch modeling-cohort (C-statistic German validation-cohort: 0.73, CI 0.69–0.77 vs. C-statistic Dutch modeling-cohort: 0.71, CI 0.69–0.73). Similar results were obtained in most of the subgroup analyses stratified by age, type of surgery and intrinsic biological subtypes.ConclusionThe outcomes of this external validation underline the generalizability of the INFLUENCE-nomogram beyond the Dutch population. The model performance could be enhanced in future by incorporating additional risk factors for LRR.
Highlights
Vinzenz Voelkel and Teresa Draeger contributed as first authors; Sabine Siesling and Miha Lavric contributed as senior authors
Tumor, and treatment characteristics, it estimates the individual risk of developing a recurrence within the first 5 years after surgery, as well as conditional annual risks based on multivariable logistic regression models (Witteveen 2019; Witteveen 2015)
This study aims to test the external validity of the INFLUENCE-nomogram on a representative cohort from a large German clinical cancer registry with additional emphasis on important patient subgroups
Summary
Vinzenz Voelkel and Teresa Draeger contributed as first authors; Sabine Siesling and Miha Lavric contributed as senior authors. In 2015, Witteveen et al developed a “prognostic nomogram for the estimation of annual risk of locoregional recurrence in early breast cancer patients” (Witteveen et al 2015). This so-called INFLUENCE-nomogram is based on over 37,000 patients of the Netherlands cancer registry (NCR) from the years 2003–2006. To assess the validity of this online tool, it was tested successfully on another Dutch cohort of more than 12,000 patients from the years 2007–2008 (Witteveen et al 2015) Until today it is unclear whether the nomogram is generalizable to foreign populations and health care systems, which would contribute to demonstrate its clinical relevance. This study aims to test the external validity of the INFLUENCE-nomogram on a representative cohort from a large German clinical cancer registry with additional emphasis on important patient subgroups
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