It must be said that most of the papers reviewed are far from ideal to prove the relationship of extraesophageal cancer and GERD. A single study addressed the association of lung cancer and GERD. Not all studies showed a relationship between GERD and head and neck cancer, and even in studies showing positive association this is not too strong. Some present with a small number of patients, most do not control cases based on tobacco usage and obesity. Moreover, the diagnosis of GERD is variable, not always from an objective measurement such as pH monitoring but relying on symptoms that has been shown not to be a trustworthy method for correct GERD diagnosis. Different previous publications showed that symptoms are unreliable for the diagnosis of GERD[65,66] although the labeling of patients as refluxers based on symptom questionnaires is still a common practice, in spite of the fact that most of these questionnaires were not validated in comparison to esophageal ambulatory pH monitoring