Smoking and body mass index as risk factors for subtypes of cancer of unknown primary

摘要

Dear Sir, Cancer of unknown primary site (CUP) accounts for 3-5% of all cancer but because it is a fatal disease it ranks high among causes of cancer deaths. It has been called "an orphan disease" because it is diagnosed through metastatic tissue and the primary tumor often remains undetected. Based on autopsy data, the most common primaries were lung (27%), pancreas (24%), liver/bile (8%) and kidney/adrenals (896). CUP can be called "orphan disease" also because, as a metastatic disease, it is disregarded as a cancer entity when only primary cancers are considered. Thus, hardly anything is known about the underlying causes or risk factors. A recent European study published in this Journal showed that heavy smoking causes a risk of 3.66 for CUP patients of diverse and unspecified histologies; alcohol drinking and wide waist circumference were borderline risk factors.