Screening markers, evaluation

Serum cancer antigen 125 (CA-125) is the most extensively evaluated tumor marker for ovarian cancer. Unfortunately, the CA-125 determination is non-specific, and elevated levels can be associated with a number of other gynecologic and gastrointestinal diseases. CA-125 levels in a woman without ovarian cancer, though, are static or tend to decrease over time, whereas levels associated with malignancy will continue to rise.10 Since CA-125 is a non-specific marker, there is no standard recommendation for routine screening for prevention of ovarian cancer. 

In the majority of DPD defective patients experiencing severe 5-FU toxicity, abnormally high levels of natural pyrimidines are present in plasma and/or urine [62]. Moreover, endogenous dihydrouracil/uracil ratio in plasma has been proposed as a measure of 5-FU catabolic deficiency in cancer patients [63], and screening of cancer patients for these simple markers should be prospectively evaluated. 

An ideal tumor marker would be a molecule specific to one type of tumor (100% specificity, i.e. no false positives) and detectable right from the initial stage of the disease (100% sensitivity, i.e. no false negatives). It would be undetectable in healthy subjects, and enable the screening and diagnosis of cancer. The tumor marker level should correlate closely with tumor size, contribute to the initial extension of the profile and evaluation of therapeutic efficacy, as well as the early detection of recurrent diseases. 

Most sarcomatoid mesotheliomas express keratin (usually low molecular weight keratin), vimentin, and frequently muscle-specihc/alpha actin. In our experience, a relatively small percent (10% to 20%) of sarcomatoid mesotheliomas express calretinin, and most sarcomatoid mesotheliomas do not express cytokeratin 5/6. Most sarcomatoid mesotheliomas express CK7, often intensely. In our experience, sarcomatoid mesotheliomas (and tumors with which they may be confused) do not express the negative markers used to evaluate potential epithelial mesotheliomas, including CEA, LeuMl, B72.3, BerEP4, BG8, and TTF-1. Therefore, we would not include these antibodies in a screen of a malignant spindle cell proliferative lesion of the pleura. 

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