Patients with suspected cancer (SCAN) and cancer of unknown primary tumor (CUP) are vulnerable because the investigation is difficult and expensive and have poor prognosis because few effective established curative treatments are available. Great progress has been made, for example through highly qualified and systematic clinical investigations not least within the framework of the standardized care processes. However, there is a need for faster, less invasive and more cost-effective tests to confirm or exclude the diagnosis of carcinoma (epithelial cancer), primarily for SCAN and secondly for CUP, and partly to receive suggestions for localization of the primary tumor for primarily CUP and secondly SCAN. There is also a need for prediction of molecularly targeted therapies.

New research provides opportunities for using a blood test to acquire detailed and updated information about the individual patient's disease and thus also open new opportunities for faster, less invasive and more cost-effective diagnosis and prediction of molecularly targeted treatments based on individualized sampling and molecular stratification. It is important that these opportunities are tested in a timely fashion in practical health care, so the new opportunities can be taken advantage of and developed in the best way. The aim is to establish a new "best practice" for these hard-to-study and difficult-to-treat patients.

Samples will be taken of epithelial cells circulating in the blood, and of the free circulating DNA.

As a reference, germ-line DNA will also be sampled, also from regular blood samples.

The analyses will show whether the cellular and molecular tests can work in the existing standardized care processes for SCAN and CUP, or if adaptations in routines, training or equipment need to be introduced.

The analyses will also give an indication of whether the cellular and molecular sample analyses provide practically useful information for confirming or refuting the diagnosis of cancer, suggesting from which organ the cancer originated and for predicting individualized therapies, and whether adaptations in routines, training or technology need to be introduced.

Inclusion Criteria:

• 200 patients who were referred to be investigated and diagnosed at the Diagnostic Centre (DC) in Södertälje, Sweden, for suspected cancer (SCAN) with serious non-specific symptoms with signs of cancer, or with suspected cancer of unknown primary (CUP) and which give informed consent to participate in the study.

Exclusion Criteria:

• All patients who have been referred and consented are included.

Patients who were referred to be investigated and diagnosed at the Diagnostic Centre (DC) in Södertälje, Sweden.

There is no plan to make individual participant data (IPD) available to other researchers