IL17A and neoplasm: Owing to the fact that it was shown that PGE(2) leads to Th17 expansion (Chizzolini et al, 2008) and that PGE(2) leading to a rapid increase of RORγτ and the selective enrichment of IL-17-producing cells by modulating the proliferation of memory T cells (Napolitani et al, 2009), we could show that PGE(2) levels in HNSCC lead to a strong enhancement of Th17 cell expansion directly at the tumour site and in TDLNs.