Estimating recurrences prevented from using trastuzumab in HER-2/neu-positive adjuvant breast cancer in the United States.

BACKGROUND: Breast cancer recurrence is associated with significant morbidity, mortality, and cost. Patients with early stage HER2+ tumors are at increased risk of recurrence. The use of trastuzumab for these patients has been shown to reduce recurrences and improve overall survival.
METHODS: A Monte Carlo simulation was conducted based on Surveillance, Epidemiology, and End Results incidence rates for 2005, United States Census data for 2005, and the results of key trials of the adjuvant use of trastuzumab. Patients included in this analysis had incident, HER2+, stage I to III breast cancer. The number of recurrences that could be prevented with trastuzumab, the cardiac adverse events that might occur, and the associated cost savings were estimated.
RESULTS: Approximately 31,200 women had HER2+ breast cancer in 2005, of whom 7298 would have had a recurrence over the subsequent 5 years despite standard of care adjuvant treatment. If trastuzumab were added to their regimen, 2791 women might have avoided recurrence, and 948 may have had an asymptomatic or symptomatic cardiac adverse event, for a ratio of expected recurrences to cardiac adverse events of 3.2 (95% confidence interval, 1.5-5.9). In economic terms, avoidance of future breast cancer recurrences was associated with lifetime reduction in future direct and indirect costs on the order of $240 million to $1.7 billion.
CONCLUSIONS: On the basis of the simulation results, targeting HER2+ tumors with trastuzumab in the adjuvant setting should prevent a significant number of women from recurrence events, with important outcomes for patients, physicians, payers, and society.