Assessing the Outcome of Cryoablation Treatment on Different Molecular Subtypes of Low-Grade Breast Cancer

Overview

This study aimed to evaluate the effectiveness of ultrasound-guided cryoablation in different molecular subtypes of low-grade breast cancer. Twenty-eight inoperable patients (as deemed by a multidisciplinary group) 73.4 years old (mean) with 28 biopsy-confirmed malignant underwent ultrasound-guided cryoablation + hormone therapy in Careggi Hospital-University Medical Center, Diagnostic Breast Unit, Florence, Italy. In addition, all patients had ultrasound visible unifocal lesion (confirmed by contrast-enhanced mammography), smaller than 30 mm invasive ductal carcinomas, low grade, hormone-receptor-positive, and HER2-negative. The lesion reduction rate was followed at 1, 3, and 6 months by ultrasound. Contrast-enhanced mammography and core needle biopsy, at 1 year, were used to determine the absence of residual tumoral cells.

Tumor Size Reduction

Follow-up ultrasounds showed that after 1 month, the average tumor size decreased by 20.14%. After 3 months, tumors had shrunk by 66.42%. By 6 months, tumors showed an average reduction of 94.03%, with some shrinking by as much as 100%.

Analysis by Molecular Subtype

The authors did further analysis for patients grouped based on the molecular subtype: Luminal (Luminal-A vs. Luminal-B), Ki67 percentage (<20% vs. ≥20%), and lesion size (<1 cm vs. ≥1 cm). Luminal-A lesions consistently showed higher reduction rates than Luminal- Lesions disappeared earlier in Luminal-A cases, with 6 vs. 2 showing complete resolution at 1 month and 9 vs. 5 in 3 months. At 6 months, all Luminal-A lesions (14/14) were resolved, while 2/14 Luminal-B lesions still retained a recognizable hypoechoic nodule. Lesions with smaller size (<1 cm) and lower Ki67% had the highest reduction rate and fastest size reduction (not statistically significant (Fisher and Chi-square tests)).

Long-Term Effectiveness

At 12 months, contrast-enhanced mammography revealed no enhancement in all Luminal-A lesions, while 2/14 Luminal-B lesions showed suspicious enhancement, confirmed by biopsy to contain residual malignant cells.

Conclusion

Consequently, the authors concluded that ultrasound-guided cryoablation proved most effective for Luminal-A lesions, where the absence of enhancement on post-procedural contrast-enhanced mammography and the lack of residual cells confirmed its efficacy, suggesting that contrast-enhanced mammography enhancement disappearance is a predictive marker for successful cryoablation.