Weekly treatment with irinotecan plus fluorouracil and leucovorin is superior to a widely used regimen of fluorouracil and leucovorin for metastatic colorectal cancer in terms of progression-free survival and overall survival.
Background-Gastrointestinal stromal tumor (GIST) is the most common sarcoma of the intestinal tract. The standard treatment of localized, primary GIST has been surgical resection alone. Most GISTs have a mutation in the KIT proto-oncogene, or less commonly in platelet-
In patients treated on phase III adjuvant colon clinical trials, DFS and OS are highly correlated, both within patients and across trials. These results suggest that DFS after 3 years of median follow-up is an appropriate end point for adjuvant colon cancer clinical trials of fluorouracil-based regimens, although marginally significant DFS improvements may not translate into significant OS benefits.
Selected patients with asymptomatic primary colorectal tumors who present with incurable metastatic disease may safely avoid resection of their primary lesions, with an anticipated low rate of hemorrhage, perforation, or obstruction before death from systemic disease. No survival advantage is gained by resection of an asymptomatic primary lesion in the setting of incurable stage IV colorectal cancer.
Targeted therapy to inhibit the kinase activity of KIT is a rational approach to the treatment of KIT-positive malignancies. Two key factors are the potency of a given inhibitor and the relative contribution of KIT activation to the growth of the tumor. Given our current understanding of KIT activity in human malignancy, the best candidate diseases for treatment with KIT inhibitors are GIST, mastocytosis, seminoma and possibly some cases of AML. Additionally, KIT inhibitors may play an adjunctive role in diseases such as small-cell lung cancer, in which KIT activation is secondary to ligand binding rather than an acquired mutation.
A B S T R A C T PurposeThe ACOSOG (American College of Surgeons Oncology Group) Z9001 (Alliance) study, a randomized, placebo-controlled trial, demonstrated that 1 year of adjuvant imatinib prolonged recurrence-free survival (RFS) after resection of primary GI stromal tumor (GIST). We sought to determine the pathologic and molecular factors associated with patient outcome.
Patients and MethodsThere were 328 patients assigned to the placebo arm and 317 to the imatinib arm. Median patient follow-up was 74 months. There were 645 tumor specimens available for mitotic rate or mutation analysis.
ResultsRFS remained superior in the imatinib arm (hazard ratio, 0.6; 95% CI, 0.43 to 0.75; Cox model-adjusted P Ͻ .001). On multivariable analysis of patients in the placebo arm, large tumor size, small bowel location, and high mitotic rate were associated with lower RFS, whereas tumor genotype was not significantly associated with RFS. Multivariable analysis of patients in the imatinib arm yielded similar findings. When comparing the two arms, imatinib therapy was associated with higher RFS in patients with a KIT exon 11 deletion of any type, but not a KIT exon 11 insertion or point mutation, KIT exon 9 mutation, PDGFRA mutation, or wild-type tumor, although some of these patient groups were small. Adjuvant imatinib did not seem to alter overall survival.
ConclusionOur findings show that tumor size, location, and mitotic rate, but not tumor genotype, are associated with the natural history of GIST. Patients with KIT exon 11 deletions assigned to 1 year of adjuvant imatinib had a longer RFS.
Targeted therapy to inhibit the kinase activity of KIT is a rational approach to the treatment of KIT-positive malignancies. Two key factors are the potency of a given inhibitor and the relative contribution of KIT activation to the growth of the tumor. Given our current understanding of KIT activity in human malignancy, the best candidate diseases for treatment with KIT inhibitors are GIST, mastocytosis, seminoma and possibly some cases of AML. Additionally, KIT inhibitors may play an adjunctive role in diseases such as small-cell lung cancer, in which KIT activation is secondary to ligand binding rather than an acquired mutation.
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