Decision analysis: MIBI imaging of nonpalpable breast abnormalities.

UNLABELLED

Scintimammography using sestamibi has provided exciting preliminary results in evaluating suspicious breast lesions. A computer simulation was performed using projected test characteristics to guide future studies and to evaluate the clinical and financial consequences of the anticipated use of noninvasive breast evaluation strategies.

METHODS

A decision analysis model compared sestamibi breast imaging, stereotaxic core biopsy and surgical biopsy as breast evaluation strategies for hypothetical cohorts of 1000 women with nonpalpable breast lesions. All women with a negative original procedure would have a 6-mo follow-up. Sensitivity and specificity were estimated from the literature and from a recent multicenter assessment for sestamibi. Probabilities of 10% for both invasive cancer and in situ cancer were based on mammographic features. Costs were based on the costs incurred by patients who were evaluated at our institution and the costs of sestamibi projections.

RESULTS

Per 1000 women, core biopsy was projected to miss about seven invasive and 10 in situ cancers more than would surgery. Sestamibi imaging was projected to miss an additional 16 invasive cancers and 12 in situ cancers, compared to core biopsy. Most misses would be detected at 6-mo follow-up. Compared to immediate surgery, the cost would be reduced by 20% with the core biopsy and 39% with the sestamibi strategy. Sixty-five percent of women having sestamibi imaging would avoid any invasive biopsy. The projected cost savings of core biopsy or sestamibi imaging, compared to surgery, ranged fom $17,700 to $77,500 per delayed cancer diagnosis.

CONCLUSION

If sestamibi imaging has similar test characteristics outside the research setting, then sestamibi imaging or sterotaxic core biopsy will lead to substantial cost savings compared to surgery with a slight compromise in the rate of early cancer detection. A decision analysis simulation can aid in designing clinical trials and exploring new strategies. The adopting of nonsurgical biopsy techniques will likely depend on confirming or establishing their test characteristics in lower-risk lesions, the natural history of cancers whose diagnosis is delayed and patient preferences of the value on avoiding any form of breast biopsy.