A retrospective analysis of the potential benefits of surgery following treatment with imatinib (Gleevec) suggests a clear benefit in both OS and PFS in patients with metastatic or recurrent GIST when compared with those who received imatinib therapy alone.
Seong Joon Park, MD
A retrospective analysis of the potential benefits of surgery following treatment with imatinib (Gleevec) suggests a clear benefit in both overall survival (OS) and progression-free survival (PFS) in patients with metastatic or recurrent gastrointestinal stromal tumors (GIST) when compared with those who received imatinib therapy alone. The findings were presented at the 10th Annual Gastrointestinal Cancers Symposium held January 24-26 in San Francisco, California.
GI stromal tumors are relatively uncommon, with approximately 4000-5000 new cases each year, according to the American Cancer Society. The tumors occur most frequently in the stomach (approximately 60%) and small intestine (approximately 30%), but may be found anywhere in the GI tract. Most patients are ≥50 years of age, and the disease is slightly more common in men.
Previous retrospective studies have shown survival benefits from surgery in GIST patients after treatment with imatinib, but these outcomes have not been compared with those of patients who did not have surgery, the focus of this study led by Seong Joon Park, MD, a fellow at Asan Medical Center in Seoul, South Korea. “Many clinicians think that adding surgery is beneficial to the patient if the patient is responsive to imatinib, but the clinical evidence for this is very scarce,” he noted.
Although patients respond to imatinib when used as first treatment for metastatic or recurrent GIST, most patients develop secondary resistance, said Park. For about one-third of these patients, residual lesions can be surgically removed, after considering tumor size and other patient characteristics.
For this study, researchers examined survival among 134 patients who showed clinical response to imatinib or achieved disease stabilization for at least 6 months. Those patients who had surgical resection of residual lesions after imatinib comprised the SI group (n = 42); their outcomes were compared with those who received imatinib therapy (IM) without surgery (n = 92). Patients in the SI group had surgical resection at a median of 19.1 months of treatment with imatinib.
After median follow-up of 58.9 months, PFS in the SI group was 87.7 months, versus 42.8 months in the IM group (P = .001); OS was 88.8 months in the IM group but not reached in the surgery group (P = .001). Factors associated with improved PFS, according to investigators, were low initial tumor burden, female gender, and presence of the KIT exon 11 mutation.
Patient and tumor characteristics were similar between the SI and IM cohorts, with the exception of median age (51 and 58 years, respectively) and metastases to the peritoneum (12 in the SI group and 56 in the IM group). Park explained that these differences are a reflection of clinical practice, insofar as surgery is often recommended in younger patients with good performance status and can be difficult in patients with multiple peritoneal metastases.
“This study really provides provocative evidence that taking an aggressive approach surgically, in addition to medical treatment with imatinib, may, in fact, result in even longer survival of patients with GI stromal tumors,” said Neal Meropol, MD, Professor of Medicine and Division Chief, Department of Hematology and Oncology, at the Case Western Reserve University School of Medicine.
Park noted that it is very important for patients to find the right medical center for their treatment, with surgeons and multidisciplinary teams experienced in treating and managing GI stromal tumors. “Those two characteristics are key for patients in selecting an appropriate place to go for their treatment,” concluded Meropol.
Park SJ, Ryu M-H, Ryoo B-Y, et al. The role of surgical resection following imatinib in patients with metastatic or recurrent GIST. Presented at: 10th Annual Gastrointestinal Cancers Symposium; January 24-26, 2013; San Francisco, CA. Abstract 62.