Objectives: Endometrial cancer is the most common gynecologic malignancy in the United States. Adjuvant radiotherapy in patients with intermediate risk disease (stage IB, IC, and occult stage II) is controversial. Despite no proven survival advantage, a significant number of women undergo this treatment annually. The purpose of this study was to compare the estimated health and economic outcomes for adjuvant whole pelvic radiotherapy to no treatment with salvage therapy for recurrence.
Methods: A decision analytic model was created to estimate the costs of adjuvant pelvic radiotherapy versus no adjuvant radiotherapy in patients with intermediate risk endometrial cancer. Data used was gathered from published literature and institutional data on costs. The model incorporates complications, recurrence rates, treatment of recurrence, and survival in each group.
Results: In the base case analysis, adjuvant pelvic radiation reduced the recurrence rate by 50%. Cost-effectiveness as measured by cost per recurrence prevented was highly sensitive to the probability of recurrence and the efficacy of adjuvant therapy. In our model the mean costs of Strategy 1 with observation and treatment reserved until the time of recurrence would be $5016. In contrast the mean cost of Strategy 2 which incorporated adjuvant radiotherapy would be $21,159. Cost per recurrence prevented based on the incremental cost-effectiveness is thus $225,215. In the highest risk subgroup, using the upper limit of the 90% confidence limit of efficacy seen in GOG Protocol 99, cost/recurrence prevented was approximately $50,000. Results did not differ when using parameters solely from GOG 99 or PORTEC.
Conclusions: Although adjuvant pelvic radiation does not appear to improve survival for intermediate risk endometrial cancer patients, it does prevent recurrences, at a net positive cost compared to no therapy. Data are not currently available to incorporate quality of life information into cost-effectiveness analyses. Obtaining such data would allow cost/quality-adjusted life year gained to be estimated. This information is necessary to determine if the extra costs of adjuvant radiotherapy in patients with intermediate risk endometrial cancer are acceptable by current health care policy standards.