While this may suggest that the prognostic impact of HOTTIP could differ between the main histological subtypes, the sub-analysis in the different histological subtypes in our cohort (Additional file 3: Figure S2) did not produce conclusive results, probably due to the small size of the sub-groups (55 adenocarcinomas and 36 squamous cell carcinomas). This evidence concerns the gene HOTTIP and squamous cell carcinoma.