Comparison of the long-term risk of recurrence and other clinical outcomes in GIST patients receiving imatinib as adjuvant therapy--a retrospective chart extract-based approach

The efficacy of adjuvant imatinib therapy in improving the prognosis of patients with colorectal gastrointestinal stromal tumours

INTRODUCTION

Although it has now been accepted that imatinib is a valid treatment for gastrointestinal stromal tumour (GIST) patients in the adjuvant setting, information on its clinical efficacy in improving the prognosis for patients with colorectal GISTs is limited.

METHODS

The clinical and follow-up records of 42 colorectal GIST patients who underwent surgical resection at our institution between January 2004 and December 2013 were reviewed retrospectively. The effect of postoperative imatinib treatment on recurrence free survival and overall survival time was analysed with the Kaplan-Meier method and the multivariate Cox proportional hazards model.

RESULTS

Sixteen patients were assigned to imatinib treatment (imatinib group) after surgical tumour resection while twenty-six patients did not receive any adjuvant treatment (control group). The one, three and five-year recurrence free survival rates were 100%, 90% and 77% respectively. This was significantly higher than in the control group (92%, 53% and 36%) (logrank test, p=0.012). The one, three and five-year overall survival rates were 100%, 91% and 68% in the imatinib group compared with 96%, 77% and 39% in the control group (logrank test, p=0.021). Analysis with the multivariate Cox regression model yielded similar results on the efficacy of adjuvant imatinib in prolonging both recurrence free survival (hazard ratio [HR]: 0.23, 95% confidence interval [CI]: 0.07-0.80) and overall survival (HR: 0.20, 95% CI: 0.05-0.91).

CONCLUSIONS

Adjuvant imatinib therapy seems to be effective in decreasing the risk of tumour occurrence and prolonging the overall survival time in colorectal GIST patients.

The economic burden of gastrointestinal stromal tumor (GIST) recurrence in patients who have received adjuvant imatinib therapy

OBJECTIVE

To estimate the economic burden of gastrointestinal stromal tumor (GIST) recurrence in patients who received imatinib adjuvant therapy.

METHODS

Data from the MarketScan and PharmMetrics databases between January 2000 and March 2013 were extracted. Patients who had received at least one diagnosis of GIST, had undergone a primary surgery for GIST, and had received at least one prescription for imatinib were included in the analysis. An algorithm was applied to identify those who had a subsequent GIST recurrence. Patients who experienced a recurrence and those who did not have a recurrence were compared for differences in healthcare utilization measures and healthcare costs within 6 months after the recurrence, while adjusting for potential confounding factors.

RESULTS

A total of 540 patients with primary resectable GIST who received imatinib adjuvant therapy were identified, including 444 (82.2%) patients who did not experience GIST recurrence and 96 (17.8%) patients who did experience recurrence. Patients who experienced GIST recurrence utilized significantly more healthcare resources in all categories than patients who did not have a recurrence, including the number of hospitalizations, days of hospitalization, emergency room visits, outpatient visits, and other medical services (all p-values <0.01). The total healthcare cost was significantly higher for patients with GIST recurrence, with a difference of $4464 per patient per month (p < 0.01). Both the medical and pharmacy costs were significantly higher with adjusted differences of $3488 and $1423 per patient per month, respectively (both p-values <0.01).

CONCLUSIONS

Patients who had GIST recurrence after surgical resection incurred significantly more healthcare resource utilization and greater healthcare costs within 6 months after the recurrence than patients who did not have recurrence. These findings suggest that GIST recurrence is associated with a substantial economic burden.