Initiation of cancer investigations in general practice Background Close to 90% of all cancers are diagnosed because the patient presents symptoms and signs. Of these patients, 85% initiate the diagnostic pathway in general practice. Therefore, the initiation of a diagnostic pathway in general practice becomes extremely important. On average, a general practitioner (GP) is involved in 7500 consultations each year, and in the diagnostic process of 8-10 incident cancers. One half of cancer patients consult their GP with either general symptoms, which are not indicative of cancer, or vague and non-specific symptoms. The other half present with what the GP assess as alarm symptoms. Three months prior to diagnosis, patients who are later diagnosed with cancer have twice as many GP consultations than a comparable reference population. Thus the complex diagnostic process in general practice requires the GP to react on very different and vague symptoms to ensure early cancer diagnosis. To enable earlier cancer diagnosis, we need much more knowledge and a better understanding of the initiation of cancer-specific tests and investigations in general practice. Aim To investigate how, how often and on which background investigation for suspected cancer is initiated in general practice. Methods Participating Danish GPs will fill in an electronic questionnaire after random consultations. A total of 70,000 consultations will be included. Perspectives The results will show how often and why GPs suspect cancer, how they perform the initial investigations and whether this process can be supported and optimised. This insight is crucial in order to improve the diagnostic pathway.