XXXX of unknown primary is associated with @entity6 .

@entity2175 @entity286 @entity1 @entity6 @entity5 @entity344 @entity1723 @entity3
UNASSIGNED: The incidences of both @entity1723 ( @entity1723 ) and @entity2175 are increasing worldwide. @entity2175 is associated with many @entity5 . However, no data are available on @entity5 of unknown primary (CUP), a relatively common, fatal @entity5 for which @entity286 smoking is the only known risk factor. At diagnosis, CUP @entity3 are found in various organs, which has implications for prognosis. We carried out a nationwide study on the association of CUP with @entity1723 and @entity2175 . 32   600 @entity1723 @entity1 and 178   000 @entity2175 @entity1 were identified from the national healthcare registers and these were linked to the Swedish @entity5 Registry. Standardized incidence ratios (SIRs) were calculated for CUP from 1997 through 2010 using anyone without @entity6 as a reference. The SIR of CUP in 421 @entity6 @entity1 was 1.71, highest for CUP with liver (2.17) and respiratory system (1.95) @entity3 . The SIR was 2.91 for @entity1723 , but with a small number of @entity1 , 1.38 for @entity2175 with insulin treatment, and 1.78 for the main group of @entity2175 . CUP with liver and respiratory system @entity3 increased for each @entity6 type; however, for @entity2175 , CUP with @entity344 also increased. The results provide the first demonstration that CUP is one of the @entity5 associated with @entity6 , with definite evidence on @entity2175 . CUP has a poor prognosis, which may be even worse when @entity6 is the underlying comorbidity. A mechanistic question for future work is to determine whether @entity6 promotes primaries that escape detection or their metastatic spread.
