About 5% of all metastatic cancers come from the primary in an organ that cannot be securely identified. This may make assigning therapy difficult. The histology of the location may or may not give sufficient clues to where the cancer rose. The usually recommended approach is to use various stains to try to pinpoint the area of origin and then treat for that type of cancer. However, this is not always possible.
When the primary site is not identified and when it does not fall neatly into certain specific clinical patterns, empiric front line broad-spectrum chemotherapy is recommended by NCCN. The issue remains second line chemotherapy. Erbitux is approved for second line treatment of squamous cell cancer of head and neck and is an attractive candidate for squamous unknown primary cancers. Unfortunately, these patients have a dismal prognosis despite management with a variety of chemotherapeutic combinations in small clinical studies. A recent meta-analysis showed no evidence of superior efficacy of any of the administered regimens incorporating platinum salts, taxanes or new generation cytotoxic compounds (gemcitabine, vinca alkaloids, irinotecan). Modest if any survival prolongation and symptom palliation with preservation of quality of life are the only realistic aims of therapy for these patients. Consequently, low-toxicity patient-convenient chemotherapy regimens should be administered to reasonably fit poor-risk patients. Currently neither ESMO nor NCCN recommend Erbitux even in first line. NCCN recommendations do not include Erbitux(OCC-B, 1) and neither guideline recommends second line chemotherapy.
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