Suspected Cancer Symptoms and Blood Test Results in Primary Care Before a Diagnosis of Lung Cancer: A Case–Control Study

Aim: To compare symptoms and blood test results prior to cancer diagnosis in individuals who developed lung cancer and those who did not. Patients & methods: Nested case–control study, lung cancer patients were matched to up four controls with no record of cancer. Differences in symptoms and blood test results were investigated in the 2-year period prior to diagnosis. Results: 26,379 lung cancer patients were matched to 92,125 controls. Elevated C-reactive protein (CRP) was independently predictive of lung cancer at every 2-month interval 12 months prior to diagnosis. Elevated CRP in conjunction with at least one symptom was associated with greater than fourfold higher odds of lung cancer. Conclusion: CRP may be a prediagnostic marker for lung cancer, and when present with other symptoms could facilitate the investigation of high-risk individuals.