Contrast-Enhanced Spectral Mammography Assessment of Patients Treated with Neoadjuvant Chemotherapy for Breast Cancer

Abstract

Background: Evaluating the tumor response to neoadjuvant chemotherapy is key to planning further therapy of breast cancer. Our study aimed to evaluate the effectiveness of low-energy and subtraction contrast-enhanced spectral mammography (CESM) images in the detection of complete response (CR) for neoadjuvant chemotherapy (NAC) in breast cancer.

Methods: A total of 63 female patients were qualified for our retrospective analysis. Low-energy and subtraction CESM images just before the beginning of NAC and as a follow-up examination 2 weeks before the end of chemotherapy were compared with one another and assessed for compliance with the postoperative histopathological examination (HP). The response to preoperative chemotherapy was evaluated based on the RECIST 1.1 criteria (Response Evaluation Criteria in Solid Tumors).

Results: Low-energy images tend to overestimate residual lesions (6.28 mm) and subtraction images tend to underestimate them (2.75 mm). The sensitivity of low-energy images in forecasting CR amounted to 33.33%, while the specificity was 92.86%. In the case of subtraction CESM, the sensitivity amounted to 85.71% and the specificity to 71.42%.

Conclusions: CESM is characterized by high sensitivity in the assessment of CR after NAC. The use of only morphological assessment is insufficient. CESM correlates well with the size of residual lesions on histopathological examination but tends to underestimate the dimensions.

Keywords: breast cancer; complete response; contrast-enhanced spectral mammography; neoadjuvant chemotherapy; response evaluation criteria in solid tumors.

Figure 1

Correlations between: (A) the maximum tumor size before NAC in low-energy and subtraction CESM images: R = 0.89, p < 0.01; (B) the maximum tumor size after NAC in low-energy and subtraction CESM images: R = 0.57, p < 0.01.

Figure 2

Correlations between: (A) the maximum tumor sizes after NAC in low-energy CESM images and in histopathology results: R = 0.26, p < 0.04; (B) the maximum tumor sizes after NAC in low-energy CESM images and in histopathology results: R = 0.67, p < 0.01.

Figure 3

ROC curves based on the tested diagnostic methods (Youden Index:0.44, proposed cut-off point: 1.00): (A) for low-energy CESM images, the value of the AUC field was 0.718 at a standard error of 0.091 and p < 0.0172; (B) for subtraction CESM images, the value of the AUC field was 0.755 at a standard error of 0.064 and p < 0.0001.

Figure 4

Assessment of therapeutic response in low-energy MLO (A,C) and subtraction MLO (B,D). Before NAC, a tumor can be seen in the upper outer quadrant of the right breast with high density and polycyclic outlines, accompanied by enlarged lymph nodes in the axillary fossa (A), revealing pathological contrast enhancement in subtraction CESM images (B). Following NAC, in the tumor field, there is a visible focal asymmetry, with a density lower than the residual glandular tissue (C), without pathological contrast enhancement (D). Based on the low-energy images, the therapeutic response was classified as partial response (PR). Based on the subtraction images, the therapeutic response was classified as complete response (CR), which was acknowledged in the HP examination.

Figure 5

Assessment of therapeutic response in low-energy CESM CC images (A,C) and subtraction CESM CC images (B,D) before NAC (IDC LumB, G2 T3N1)showing irregular infiltration on the border of the outer quadrants of the left breast with high density (A), revealing pathological contrast enhancement on subtraction CESM images (B). Additionally, satellite foci are visible in subtraction CESM images, which were confirmed in core-needle biopsy (smaller arrow) (B). Following NAC, there was a visible focal asymmetry, with a density slightly lower than the infiltration before NAC (C), shown again without pathological contrast enhancement (D). Based on the low-energy CESM images, the therapeutic response was classified as stable disease (SD). Based on the subtraction CESM images, the therapeutic response was classified as complete response (CR), which was acknowledged in the HP examination.