Abstract
This study evaluated the role of 99mTc-sestamibi washout in the prediction of pathologic tumor response to neoadjuvant chemotherapy in 30 patients with locally advanced breast cancer. Methods: Two 99mTc-sestamibi studies were performed before and after chemotherapy for each patient. Early (10 min) and delayed (240 min) planar breast views were acquired after a 740-MBq 99mTc-sestamibi intravenous injection, and the washout rate (WOR) was computed. All patients underwent radical mastectomy with pathologic evaluation of the residual tumor size. Results: The pretherapy 99mTc-sestamibi WOR ranged from 14% to 92% (mean ± SD, 50% ± 18%). At pathologic examination, 15 patients showed no tumor response to chemotherapy and 15 patients showed an objective response to chemotherapy. The pretherapy 99mTc-sestamibi study predicted chemoresistance (WOR > 45%) in 18 of 30 patients and no chemoresistance (WOR ≤ 45%) in 12 of 30 patients. When the WOR cutoff was set at >45%, the prognostic performance of the test was indicated by a sensitivity of 100%; a specificity of 80%; positive and negative predictive values of 83% and 100%, respectively; and a likelihood ratio of 5. The repeatability of the test was good, with 80%–93% interreader agreement (κ = 0.57−0.85). Posttherapy 99mTc-sestamibi studies confirmed the pretherapy study prediction in 29 of 30 patients. Conclusion: 99mTc-Sestamibi WOR is a reliable test for predicting tumor response to neoadjuvant chemotherapy. In fact, negative findings (WOR ≤ 45%) rule out chemoresistance and positive findings (WOR > 45%) indicate a high risk of chemoresistance.
Footnotes
Received Aug. 14, 2001; revision accepted Feb. 4, 2002.
For correspondence or reprints contact: Rosa Sciuto, MD, via della Giuliana 83/a, 00195, Rome, Italy.
E-mail: sciuto{at}ifo.it