[1] McGill Univ, Dept Oncol, Med Phys Unit, Fac Med, Montreal, PQ, Canada
[2] UT Southwestern Med Ctr, Radiat Oncol, Dallas, TX USA
[3] McGill Univ, Hlth Ctr, Div Gastroenterol, Montreal, PQ, Canada
[4] Jewish Gen Hosp, Div Gastroenterol, Montreal, PQ, Canada
[5] Jewish Gen Hosp, Dept Oncol, Montreal, PQ, Canada