Planar scintimammography and SPECT in neoadjuvant chemo or hormonotherapy response evaluation in locally advanced primary breast cancer

Conventional imaging procedures have proved of limited value in assessing tumor response to neoadjuvant chemotherapy in locally advanced primary breast cancer (LAPBC). We evaluated the usefulness of radioisotopic procedures comparing planar scintimammography (SM) to SPECT, monitoring pre-surgery neoadjuvant chemo- or hormonotherapy response in 32 LAPBC patients. In all cases, 99mTc-tetrofosmin conventional planar SM and SPECT were acquired by dual-head gamma camera with HR parallel hole collimators. In 15 cases, planar SM with small field of view high resolution dedicated breast camera (DBC) was also acquired. Scintigraphic data always correlated with histopathological findings. At surgery, 4/32 patients had pathological complete remission (pCR), while 28/32 patients had residual tumors. Both conventional planar SM and SPECT were true negative in 4/4 (100%) pCR patients, as was DBC in the only studied case. Conventional planar SM and SPECT detected residual tumors in 23/28 (82%) and in 25/28 (89.2%) cases, respectively. Both procedures missed 2 multifocal, scattered microscopic residues, only evidenced at DBC. Conventional planar SM also missed 3 further macroscopic residues (15-20 mm), while SPECT only one of these, a mucinous BC, in which DBC was not performed. DBC correctly classified all other 12 patients in whom the procedure was performed. Both conventional planar SM and SPECT proved useful diagnostic tools in monitoring neoadjuvant chemo/hormono therapy response in LAPBC with SPECT appearing more sensitive; however, our data, although in a limited number of cases, suggest that sensitivity can further be increased using high resolution DBC, especially in detecting microscopic residual tumor foci.