Patients with ruptured gastrointestinal stromal tumors (GISTs) receiving 5 years of adjuvant imatinib treatment demonstrated more favorable recurrence-free survival (RFS) rates compared to only 3 years of adjuvant imatinib treatment, as recently published in Cancer Research and Treatment.
Investigators analyzed the data of 1409 patients found in the GIST registry of Asan Medical Center in Seoul, Korea. All 1409 patients underwent complete resections for localized GISTs. Of these 1409 patients, a total of 53 experienced GIST tumor ruptures in accordance with the Nishida classification.
Following the application of inclusion criteria, the investigators included 51 of the 53 patients in their retrospective analysis assessing 2 different durations of adjuvant imatinib therapy following GIST rupture.
The researchers divided the patients into 2 groups depending on the duration of their imatinib treatment, with 31 patients in the 3-year group and 20 patients in the 5-year group. Patients started on 400 mg of imatinib once a day with dosage adjustments made due to adverse toxicity events.
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Following the first 4-week follow-up after initiation of imatinib, all patients underwent 3-month routine follow-ups during both the 3-year and 5-year treatment periods to determine recurrence rates. These 3-month follow-ups continued for the first 2 years following cessation of imatinib treatment, and then every 6 months for the next 3 years if recurrence did not occur.
Overall survival rates in the 5-year and 3-year treatment groups were statistically similar. The researchers discovered that low mitotic count (≤ median) independently correlated with improved RFS (hazard ratio [HR] 0.20, 95% CI 0.06-0.67, P =.009), while the 5-year imatinib regimen only marginally correlated with improved RFS (HR 0.25; 95% CI 0.06-1.05, P =.058).
The investigators did not observe any statistically significant differences in toxicity profiles between the 3-year and 5-year treatment groups. No patients in the 3-year treatment group stopped imatinib treatment due to toxicity; however, 4 patients in the 5-year group discontinued their imatinib treatment due to grade 3 adverse effects including nausea and vomiting, neuropathy, skin toxicity, and fatigue.
Study limitations included the retrospective nature of the study and the selection of patients from a single treatment center. “The small number of study patients appears to be the main reason for the difference in RFS not reaching statistical significance in multivariate analysis,” the authors said.
Lastly, the results did not indicate any statistically significant difference in overall survival between the groups which potentially required a longer follow-up duration.
Kang S, Ryu MH, Bang YH, Kim HD, Lee HE, Kang YK. Adjuvant Imatinib treatment for 5-years vs 3-years in patients with ruptured localized gastrointestinal stromal tumor: a retrospective analysis. Cancer Res Treat. Published online December 6, 2021. doi:10.4143/crt.2021.1040