Suspected cancer symptoms and blood test results in primary care before a diagnosis of lung cancer: a case-control study

The majority of lung cancer cases are diagnosed symptomatically when patients present to primary care with cancer ‘alarm’ symptoms. Lung cancer is most commonly diagnosed at an advanced stage, but earlier diagnosis of lung cancer can improve patient outcomes. This study aimed to compare symptoms and blood test results captured by primary care physicians from patients who developed lung cancer, and those who did not. Data was assessed up to 2 years prior to the cancer diagnosis to help identify those at the highest risk for further investigation or referral. Over 26,000 cases and 92,000 controls were assessed, and the results indicated that elevated C-reactive protein 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. This suggests that CRP may be a useful prediagnostic marker for lung cancer, and when present with other symptoms could facilitate the investigation of high-risk individuals & earlier detection of lung cancer.

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