Calcium and Albumin Blood Tests, Ethnicity, and Cancer Incidence in Primary Care in the UK
Liz Down, Melissa Barlow, Luke T. A. Mounce, Jessica Watson, Samuel W. D. Merriel, Sarah E. R. Bailey, Tanimola Martins
Simple Summary For many common blood tests, typical values differ for patients from different ethnic groups. Although it is known that albumin and calcium tests may be useful in identifying patients with a higher-than-average cancer risk, the evidence is limited and does not take into account patient ethnicity. Examining the blood test results in a large English primary care dataset demonstrated that having either low albumin or high calcium was predictive of cancer risk, and more specifically risk of myeloma. Having low albumin was also predictive of liver cancer. There were no differences in how effective these blood tests are at estimating cancer risk for patients from different ethnic groups. Abstract Objectives: This study aimed to assess any ethnic differences in blood calcium and albumin levels for patients receiving these tests in primary care, and to investigate how this affects the use of these markers in assessing cancer risk. Methods: The analysis was based on a primary care dataset comprising patients in England. Multilevel logistic regression was used to investigate the relationship between blood test results and cancer risk by ethnic group. Results: A total of 4,632,856 patients were eligible for the albumin analysis, and 1,979,763 for the calcium analysis. Raised calcium levels were indicative of an increased risk of cancer, with diagnostic odds ratios (ORs) ranging from 2.0 to 2.7 for the different ethnic groups. ORs for myeloma were between 6.6 and 13.6. Similarly, low albumin was associated with an increased risk of cancer with an OR of between 3.2 and 3.8, myeloma (OR between 8.7 and 10.0), and liver cancer (OR between 9.2 and 15.7). Conclusions: Albumin and corrected calcium were effective indicators of cancer risk, and more specifically of risk of myeloma. Albumin levels were also linked with liver cancer risk. While there are some differences in typical corrected calcium and albumin levels between ethnic groups, there was no evidence that this had an effect on the usefulness of these markers to infer cancer risk.