Background: Evaluation of appropriateness of laboratory tests on the basis of individual requests remains a serious problem as the clinical question is usually not reported with the test order. This study explored the comparison of the rate of tumor marker orders with cancer prevalence as a putative indicator of inappropriateness.
Methods: Tumor marker orders (2011 and 2012) were obtained from the Ministry of Health and cancer prevalence from the Italian Association of Cancer Registries. The rate of tumor marker orders was matched with demographic data and tumor prevalence and examined by using the confidence interval approach. Region-to-region and year-to-year variations were also examined. Focus was placed on CEA, CA125, CA19.9 and CA15.3.
Results: Tumor markers ordered in Italy were 13,207,289 in 2012 (221.3/1000 individuals). Given an estimated prevalence of 2,243,953 cancer cases, 7.04 tumor markers appear to be requested for each prevalent case of epithelial cancer per year. The rate of requests of CEA, CA125, CA19.9 and CA15.3 (in aggregate 5,834,167 requests in 2012, 44.2% of total) from the first and the last ranked region (96 and 244/1000 individuals) are significantly different (p<0.01). Region-to-region differences do not correspond to any known variation of prevalence in the different regions.
Conclusions: The developed approach provides a proxy indicator of inappropriateness showing that tumor markers are overused in Italy and their ordering pattern is not related to tumor prevalence. The model is suitable to be validated in other laboratory tests used in diseases whose prevalence is known.