The baseline abdominal CT scan shows a hepatic mass measuring 4.8 by 3.3 cm (top) and one of several mesenteric masses measuring 3.8 by 3.3 cm (bottom) (Panel A, arrows). After 13 weeks of treatment with crizotinib, the hepatic and mesenteric masses measured 2.3 by 0.8 cm and 1.3 by 1.2 cm, respectively (Panel B, arrows). In October 2008, these masses measured 3.6 by 2.2 cm and 0.5 by 0.5 cm, respectively (not shown), indicating that the hepatic mass had regrown, despite a continued response, according to the Response Evaluation Criteria in Solid Tumors.