Background The results of Phase III of the (SSG)XVIII/AIO clinical study on imatinib (IM) in adjuvant treatment of GIST show that, after five years of follow up, 3 years of treatment lead to 66% of patients free of recurrence compared to 48% who received IM for only one year, with a 18% relative risk reduction. This result will determine the new standard of 3 years of adjuvant IM treatment in GIST patients at high risk of recurrence.

Purpose To analyse the budget impact on Piedmont Region, over 3 years, after the approval by the Italian National Regulatory Agency of 3 years’ adjuvant treatment in high-risk GIST.

Materials and Methods The analysis was performed considering the estimated incidence of 60 new cases of GIST in Piedmont: 28 patients are at very low/low risk of relapse and don’t need IM; 8 patients are at intermediate risk of recurrence and should receive IM only for 1 year; 12 patients are at very high/high risk and are treated with adjuvant IM for 3 years; 12 patients are metastatic at diagnosis and require lifelong treatment (5–13 years). The price of IM considered in this study was fixed (6–2011) in the regional competition in Piedmont (at 16.7305€/100 mg capsule).

Results The annual expenditure for 12 very high/high risk patients is 293,118.6€ which adds up to a total of 879,355.08€ in 3 years. Given the stability of GIST incidence (5 cases/1,000,000 people) and 30% drop off from treatment for intolerance as reported in the SSG/AIO study, the result of our study was: in the first year 12 patients were treated at a total cost of 293,118.36€. The second year for 20 patients (8 from the first year + 12 new) the expenditure was 488,530.6€ (+66.66%). The third year there were 27 patients (7 from the first year, 8 from the second year, 12 new) and a total amount of 659,516.31€ (+35% compared to the second year). The total expenditure on very high/high risk patients at the end of 3 years of observational study was 1,441,165.27€ and the overall incremental cost was +125%.

Conclusions The cost of health interventions in rare tumours should be carefully planned with a specific cancer and pharmacological registry. The availability of comprehensive databases or regional registries of these treatments would allow a more accurate analysis that takes into account both the cost of medicines and ambulatory treatment and follow-up cost. Even though data on current costs are alarming it is important to consider that in 2014 IM will lose the Novartis patent and costs will drop about 30–40%.

No conflict of interest.