Most commonly responsible for CUP syndromes are tumors of testis, lung, colon and rectum, and pancreas. Therefore, the study of these regions should be done very carefully.
One speaks of a carcinoma of unknown primary (CUP), when one or more tumor metastases are found in one patient, but no primary tumor can be detected in routine diagnostics. CUP syndromes are found in up to 7% of all malignancies and represent a therapeutically difficult situation because the tumor treatment is usually determined by the specific original primary tissue. Most commonly responsible for CUP syndromes are tumors of testis, lung, colon and rectum, and pancreas. Therefore, the study of these regions should be done very carefully. Among the studies to identify the primary tumor include laboratory testing imaging Immunocytochemical and Immunperoxidasefärbungen tissue examination Laboratory tests should include a complete blood count, urinalysis, faecal occult blood and serum chemistries (including prostate-specific antigen in men). The imaging should be limited to an X-ray image of the thorax, abdominal CT and mammography. An endoscopic examination of the lower and upper gastrointestinal tract should be performed when blood in the stool is present. (Editor’s note: In Germany, a barium enema is replaced by colonoscopy.) Due to the increasing number of immunocytochemical staining of available tumor material an identification of the primary tumor tissue may be possible; possibly can also tumors that arise from lung, colon or breast, are identified. In addition, an immunoperoxidase staining for immunoglobulin help chromosomal studies and immunophenotyping in the diagnosis of various subtypes of malignant lymphomas whose recognition and differentiation from other tumors (even cancer) can be difficult when they manifest themselves outside the lymph nodes. The immunoperoxidase staining of tumor cells for ?-fetoprotein and ?-human chorionic gonadotropin may indicate easily treatable germ cell tumors. Tissue studies on estrogen or progesterone receptors are vo utility in the identification of breast cancer and Immunperoxidasefärbungen to prostate specific antigen in prostatic carcinoma. Although a precise histological diagnosis is not possible, a constellation of findings may indicate a source. Poorly differentiated carcinomas near the center line of the mediastinum or retroperitoneum in male patients young or middle-aged indicate a germ cell tumor, even in the absence of a testicular mass. Patients with this type of cancer should be treated with cisplatin-based chemotherapy on, as this long reach almost 50% of these patients disease-free phases. For most tumors with unknown primary tumor response, however, is usually only moderate and of short duration (median survival <1 year) to this or to other Polychemotherapieregime.