Additionally, increased levels of serum IL-6 have been observed in patients with oesophageal squamous cell carcinoma seven days after PDT with porfimer sodium (DLI = 48 h) [46], in patients with bile duct cancer submitted to hematoporphyrin-PDT [32] and in patients with head and neck squamous cell carcinoma 12 h after PDT with Foscan (DLI = 96 h) [33], emphasising the clinical relevance of IL-6 levels. Here, IL6 is linked to bile duct cancer.