Implementation of the use of SPECT-portable for evaluation of surgical margins in breast cancer with indication of ROLL: First results

Abstract

Objectives: Main objective: To compare the effectiveness for checking surgical margins between SPECT-portable and mammography of the piece (RxM).

Secondary objective: To standardize a pre-operative protocol using SPECT-portable and to evaluate the time required in the use of this technique.

Material and methods: Prospective longitudinal study with 36 patients (39 lesions) diagnosed with breast cancer (CM) with criteria for SNOLL/ROLL. A pre-surgical study of the tumor lesion was performed, after the eco-guided administration of ^99mTc-nanocolloids of albumin/^99mTc-macroaggregates of albumin, in the tumor lesion. Hybrid images (optical + SPECT) and 3D navigation images with gamma probe are obtained using freehandSPECT. In the operating room, 4-5 images are obtained with freehandSPECT, (I) on skin for tumor location, (II) after exposure of surgical bed for resection guide, (III) of the surgical bed after exeresis, (IV and V) the anterior-posterior and lateral surface of the surgical specimen. The three criteria to decide to extend the margins are: (a) residual activity (cps) at the edges of the surgical bed resection; (b) visual analysis of the uptake in the specimen; (c) a minimum distance of 10 mm from the edges of the specimen to the center of greatest uptake, plus the radius of the lesion. We study the concordance of: the depth measurement between ultrasound and freehandSPECT; the surgical margins between freehandSPECT vs. mammography of the specimen (RxM), considering anatomical pathology (AP) as the gold standard technique as reference; surgical time used with freehandSPECT and RxM.

Results: Intraoperative localization was performed in all cases. False negative (FN: no detection margin affected) with freehandSPECT: 9 margins; with RxM: 8. True positive (TP: detection margin affected) with freehandSPECT: 5 margins, with RxM: 6. True negative (TN: consider free margin when healthy) with freehandSPECT: 213 margins; with RxM: 196. Negative predictive value (NPV: probability of negative margin on unaffected part) with freehandSPECT: 95.9%, with RxM: 96.07%. Specificity with freehandSPECT: 96.8%, with RxM: 97%. The concordance of surgical bed margins between freehandSPECT and RxM: 94.5%. Between freehandSPECT and AP: 93.1%. Between RxM and PA: 93.5%, being all statistically significant (p-value <0.000), so we can affirm that both techniques are related or dependent on the reference technique, the PA. Degree of correlation between SPECT-portable and low PA (Kappa index: 0.34, 95% CI [0.22-0.47], and between RxM and moderate PA (Kappa index: 0.42, 95% CI [0.29-0.56], p-value <0.001. Comparison of the successes and failures of both techniques (SPECT-portable and RxM) and PA: Distribution χ2: 0.023 with degree of freedom 1, with value <0.05, so we can affirm that both techniques are similar, since there are no significant statistical differences. Median total OR time: 60.25 min (30-145). Mean freehandSPECT OR time: 5 scans = 10 min.

Conclusions: There are no statistically significant differences in the probability to rule out affective margins that require a second surgery between both techniques (SPECT-portable and RxM) so, the technique performed with SPECT-Portable is a useful and effective procedure, which requires specific training with an optimized and multidisciplinary protocol. The time spent with SPECT-portable is feasible for daily practice.

Keywords: Breast cancer; Cáncer de mama; FreehandSPECT; Mammography; Mamografía; ROLL; SNOLL; SPECT portátil.