[1] Univ Sao Paulo, Med Sch, Gastroenterol Dept, Sao Paulo, Brazil
[2] Massachusetts Gen Hosp, Gastrointestinal Surg Div, Boston, MA USA
[3] Univ Fed Maranhao, Gastrointestinal Surg Dept, Sao Luis, Brazil
[4] Sao Leopoldo Mandic Med Sch, Gastrointestinal Surg Dept, Campinas, Brazil
[5] Gastromed Zilberstein Inst, 9 Julho 4440, BR-01406100 Sao Paulo, Brazil