Cancer of unknown primary origin

The acronym CUP for the English "cancer of unknown primary" ( shortened for: cancer of unknown primary origin ) has become established in German-speaking countries and replaces the previously usual designation cancer of unknown primary tumor.

Definition

From a CUP is when there are metastases without the malignant ( malignant) primary tumor is known. As a rule, these are histologically by neuroendocrine tumors such as small cell lung cancer, carcinoid tumors or malignant melanoma.

Prevalence and prognosis

In about 3-5% of all cancer patients, the primary tumor is unknown. The prognosis is very unfavorable. Less than 25% of patients survive the first year after diagnosis.

Primary tumor search

In a CUP is a histologically proven metastasis of an unknown primary tumor. The primary tumor search includes a dermatological examination of the entire skin, including ear, nose, mouth and anus, and also an extensive sonography of all internal organs, endoscopy of the stomach, intestines and lungs and studies with high-resolution imaging techniques such as computed tomography and magnetic resonance imaging in women also have a pelvic exam and a mammogram.

Formation

CUP usually arise when the primary tumor either vanishes or is very small. Since metastases usually far greater extent are degenerate as the primary tumor, it is believed that the immune system after a metastasis destroys the tumor or has however kept small while him it has not been possible with the highly malignant metastases. Another theory suggests that a part of the CUP caused by heterotopia in which, in the embryonic stage tissue was deported to other organs and degenerate there. In this case it would be at about the supposed metastasis of a malignant melanoma in the lung in fact a primary tumor.