Letter to the Editor: Carcinoma of unknown primary

Madam, Carcinoma of unknown primary site (CUP) is defined as the presence of metastatic cancer documented in the absence of identifiable primary tumour site. The criteria for CUP diagnosis includes a biopsy proved malignancy (for a cancer that could not have originated at the biopsy site), no primary tumour found after a thorough examination and normal laboratory tests including complete blood count, blood chemistry, chest x-ray, computer tomography (CT) scan of the chest, abdomen and pelvis, and mammography or prostate specific antigen test. It accounts for 3% and 5% of all cancer cases.