Short communication Breast cancer staging using technetium-99m sestamibi and indium-111 pentetreotide single-photon emission tomography Arturo Chiti 1, Roberto Agresti 2, Lorenzo S. Maffioli 1, Gorana Tomasic 3, Giordano SavellH, Flavio Crippa ~, Silvana Pilotti 3, Marco Greco 2, Emilio Bombardieril 1 Division of Nuclear Medicine, Istituto Nazionale per I0 Studio e la Cura dei Tumori, Milano, Italy 2 Division of Surgical Oncology "B", Istituto Nazionale per Io Studio e la Cura dei Tumori, Milano, Italy 3 Division of Pathology and Cytology, Istituto Nazionale per I0 Studio e la Cura dei Tumori, Milano, Italy Received 10 August and in revised form 2 September 1996 Abstract. We evaluated the clinical usefulness of single- photon emission tomography (SPET) with technetium- 99m sestamibi and indium-ll 1 pentetreotide in breast cancer staging. Fifteen patients with clinical and/or mammographic findings suggesting T1-2N0-1 breast cancer were studied. SPET images were acquired 20 rain after 99mTc-sestamibi injection and 4 and 24 h after 111In-pentetreotide injection. Patients underwent surgery the day after the later l llIn-pentetreotide acquisition. Pathological examination showed 16 tumours in the 15 patients, with one bilateral carcinoma. The mean tumour diameter was 18.7 ram. Metastatic axillary involvement was found in 6/16 tumours, with a mean of five meta- static nodes per axilla. Both tracers correctly identified 15/16 primary tumours and five of the six cases of meta- static axillary node involvement. No difference between the tracers was observed in breast cancer staging. 99mTc- sestamibi seems to be the better tracer in terms of physi- cal characteristics, execution time and cost-effectiveness. Our data suggest the future possibility of using nuclear medicine imaging to avoid axillary dissection in patients with T1 breast cancer. Key words: Breast cancer - Axillary lymph nodes - Technetium-99m sestamibi - Indium-111 pentetreotide Eur J Nucl Med (1997) 24:192-196 Introduction Among the prognostic factors in breast cancer, particular attention must be paid to regional nodal metastases, which can influence the overall and disease-free surviv- Correspondence to: E. Bombardieri, Divisione Medicina Nucle- are, Istituto Nazionale per lo Studio e la Cura dei Tumori, Via Venezian 1, 1-20133 Milano, Italy al. Axillary lymph node involvement serves as an index for the accurate staging of the disease and can be consid- ered the main parameter when planning adjuvant chemo- therapy [ 1 ]. A method enabling presurgical assessment of axillary nodes would be of value in sparing some unnecessary surgical procedures. Clinical evaluation of the axilla is an unreliable diagnostic tool, as metastatic lymph nodes often cannot be distinguished from enlarged but non- metastatic ones. Economic factors also play a role. In fact, omitting axillary lymph node dissection would be time sparing, thus significantly lowering the cost of treatment for the individual patient; this is particularly important in view of the high prevalence of the disease. New methods evaluating experimental parameters (monoclonal antibodies directed against tumour-associat- ed antigens) together with pathological factors (grading and diameter of the tumour) have recently been assessed [2, 3]. We have already employed nuclear medicine pro- cedures in this diagnostic field with encouraging results, supported by published data [4]. The aim of this study was to evaluate simultaneously the usefulness of tech- netium-99m hexakis-2-methoxyisobutylisonitrile (sesta- mibi) and indium- 111 pentetreotide for preoperative axil- lary node detection in patients with breast cancer. Materials and methods Patient population. Fifteen patients (mean age 53.9 years, range 38-65) with clinical and/or mammographic findings suggestive of T1-2N0-1 breast cancer were enrolled in this study. Preoperative physical and instrumental examinations showed no evidence of metastatic spread of the disease. All patients were untreated for their disease. We studied 16 tumours in the 15 patients; one woman had bi- lateral cancer. Six tumours were in the left breast, five in the upper outer and one in the upper inner quadrant. Ten tumours were in the right breast, eight in the upper outer, one in the central and one in the upper inner quadrant. European Journal of Nuclear Medicine Vol. 24, No. 2, February 1997 - 9 Springer-Verlag 1997