Blood sampling patterns in primary care change several years before a cancer diagnosis

A sudden increase in blood sample requisitions from primary care physicians may indicate an incentive to investigate cer-tain symptoms further. Patients with slowly progressing malig-nancies may debut with insidious symptoms and seek medical attention with increasing frequency, which indeed has been demonstrated through different markers of primary care activ-ity in the last 1–2 years prior to a cancer diagnosis [1, 2]. However, within hematological malignancies in particular, early signs of slowly progressing or pre-malignant conditions may in fact be detectable several years before the malignant disease is diagnosed [3–5]. Identifying early signs of malig-nancy or pre-malignancy is important in order to increase chances of successful treatment and lower morbidity and mor-tality [6–8]. Even in asymptomatic and otherwise low-risk hematological patients, it has been demonstrated that early detection may enable risk stratification for follow-up of the (pre-)malignant conditions, help provide relevant care and improve early disease detection in the right patients [9]. In this descriptive study we aimed to describe the pre-diagnostic activity in primary care going back 15 years prior to the malig-nant diagnosis in order to explore if laboratory activity may indicate that early (pre-)malignant conditions register in pri-mary care years before a diagnosis is made. This was done by describing the blood sampling activity patterns in primary care in both cancer patients to-be and controls, looking at both solid tumors and hematological malignancies. The overall aim of the study was to evaluate the potential for earlier diag-nosis of certain malignant diseases