Recent data showed that metastatic colorectal (mCRC) @entity5 exhibiting extended RAS- @entity817 mutations were resistant to anti- @entity470 ( @entity470 ) monoclonal antibodies, making these drugs suitable for the so-called "super" @entity164 ( @entity164 ) @entity1 only. This study aimed to compare the extended RAS- @entity817 mutation frequency and characteristics according to location of @entity5 sampling. All consecutive mCRC specimens (N   =   1659) referred to our institution from January 2008 till June 2014 were included in the analysis. @entity5 genotyping (first for @entity984 exon 2, then for @entity817 exon 15, and later for @entity984 exons 2, 3, and 4 and @entity8497 exons 2, 3, and 4) was performed with high-resolution melting analysis or allelic discrimination. The factors predicting for the presence of mutation were explored using multivariate binary logistic regression. Overall, the prevalence of @entity984 exon 2 was 36.8%, and it was lower in liver @entity3 (N   =   138/490; 28.2%) in comparison with @entity5 (N   =   442/1086; 40.7%), lung @entity3 (16/32; 50%), or other metastatic sites (15/51; 29.4%; P   <   0.0001). Similarly, in the 1428 samples analyzed, @entity817 mutations were less often found in liver @entity3 (N   =   9/396; 2.3%) as compared to @entity5 (N   =   79/959; 8.2%), lung @entity3 (N   =   2/29; 6.9%), or other metastatic locations (N   =   2/44; 4.5%; P   <   0.0002). Overall occurrence of extended RAS mutation was 51.7%. Of the 503 samples tested, the prevalence of extended RAS- @entity817 mutations was twice as low in liver @entity3 (N   =   53/151; 34.2 %) as compared to @entity5 (N   =   191/322; 59.3%, P   <   0.0001). Univariate analysis identified age  <=65 years, male gender, and liver localization as predictors of super @entity164 status. At multivariate analysis, only liver @entity3 were retained (RR 2.85 [95% CI 1.91-4.30]). @entity14 are twice as likely to exhibit a super @entity164 genotype as compared to other @entity5 locations independently from other factors. This molecular feature has the potential to influence therapeutic strategy in mCRC @entity1 .

XXXX are more often super wild type. Toward treatment based on metastatic site genotyping?

@entity1 :: ('9606', 'Species') :: ['patients'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor', 'tumors', 'primary tumors', 'Tumor'] @entity470 :: ('1956', 'Gene') :: ['EGFR', 'epidermal growth factor receptor'] @entity984 :: ('3845', 'Gene') :: ['KRAS'] @entity164 :: ('MESH:D017827', 'Disease') :: ['WT', 'wild-type'] @entity8497 :: ('4893', 'Gene') :: ['NRAS'] @entity3 :: ('MESH:D009362', 'Disease') :: ['metastases'] @entity14 :: ('MESH:D015179', 'Disease') :: ['Colorectal liver metastases'] @entity817 :: ('673', 'Gene') :: ['BRAF']
@entity14 :: (MESH:D015179,Disease) :: ['Colorectal liver metastases']
