Technetium-99m-MIBI scintigraphy in the assessment of neoadjuvant chemotherapy in breast carcinoma

Presurgical neoadjuvant chemotherapy (PSNC) is the treatment of choice for patients with locally advanced breast carcinoma (LABC). Accurate assessment of tumor response is important in planning subsequent treatments. Conventional response assessment by mammography and clinical evaluation is not fully reliable. This study evaluates the diagnostic yield of serial 99mTc-MIBI scintigraphy in the assessment of LABC response to PSNC.

Twenty-nine patients affected by LABC underwent clinical, mammographic and 99mTc-MIBI scintigraphy before and after 3 cycles of FEC (500 mg/m2 5-fluorouracil, 50 mg/m2 epirubicin and 400 mg/m2 cyclophosphamide) on Days 1 and 8. Surgery was planned for 15 days after the third cycle of chemotherapy. Pathological status was obtained after surgery in all patients.

Sensitivities (i.e., true-positive ratios) for a correct prediction of tumor presence after PSNC were 65% for scintigraphy, 35% for clinical evaluation and 69% for mammography. Specificities (i.e., true-negative ratios) for a correct prediction of tumor absence after PSNC were 100% for scintigraphy, 67% for clinical evaluation and 33% for mammography. Technetium-99m-MIBI uptake in this series did not correlate with P-170 expression, proliferating cell nuclear antigen, Her-2/neu oncogene protein, antihuman endothelial cell CD31 antigen and estrogenic and progestinic receptor status.

Technetium-99m-MIBI scintigraphy is effective in monitoring the response to PSNC in LABC patients. Its diagnostic yield is clearly superior to clinical evaluation alone. Scintigraphy performs as does mammography in patients with negative response, but it is clearly superior in patients with positive response.