Lizhi Niu, M.D., Kecheng Xu, M.D.*, Weibing He, M.D., Yisong He, M.D., Jiansheng Zuo, M.D.
Cryosurgery Center for Cancer, Fuda Cancer Hospital Guangzhou, Guangzhou 510300, China

*Corresponding Author: Kecheng Xu, M.D., Email: xukc@vip.163.com

Introduction

With recent improvements in breast imaging, the ability to identify small breast tumors has markedly improved, prompting significant interest in the use of ablation without surgical excision to treat early-stage breast cancer. A lumpectomy, which has a tremendous improvement over mastectomy, however, is still an invasive procedure, with potentially undesirable cosmetic results. Therefore, there has been an increasing interest for seeking a less invasive percutaneous ablation. Cryoablation of breast cancer has been paid a great attention. The aims of this study was to determine the efficacy of ultrasonographic (US)-guided percutaneous cryoablation for small solitary invasive breast cancer in term of the presence of residual malignancy according to pathology of specimen from lumpectomy.

Technique

Twenty-seven patients were enrolled in this study. The median age was 52.5 years (range, 34-77 years). Twenty-seven patients with small solitary invasive breast cancers underwent US-guided cryoablation. Tumor proved by core biopsy had median of 13 mm with range of 8–25 mm in size; twenty-four patients had palpable masses. Cryoablation was carried out using the argon-based cryosurgical system (Endocare, Inc., USA) which was equipped with multiple diameters of cryoprobes and was designed to create probe temperatures of -160°C according to the Joule-Thomson effect inside the tip of the cryoprobes. A variable number (one to two) of 2 or 3mm cryoprobes were placed directly into the breast mass and positioned under US-guidance. Generally, lesions smaller than 15mm could be reliably frozen with a single, centrally placed, 3-mm probe, and large lesions required multiple probes. A double cycles of freezing-thawing procedure was used. Each cryoprobe was cooled to -160 C and the resulting iceball monitored with ultrasound until frozen region encompassed the entire mass of the tumor with at least a “0.5cm safe border”. The real-time US images were obtained to document the tumor size and location before probe placement, the probe placement within the tumor, and the maximum length and width of the ice ball during cryoablation. The diameter of the ice ball in the longitudinal and transverse planes was measured during each freeze-and-thaw cycle to ensure appropriate width and length so that the ice ball encompassed the cancer with an additional margin of 8-10mm. Standard surgical lumpectomy was performed after cryoablation. The histological study for lumpectomy specimens were used to investigate presence of intraductal or invasive cancer.

Results

The probe was successfully placed under US guidance in the center of the tumor in 27 patients. Continuous US monitoring documented the size of the ice ball forming around the cryoprobe. The dimension (length × width × depth) of the iceballs after first freeze cycle of 10 minutes was 3. 9 ± 0.4cm × 4.1 ± 0.4cm × 3.5 ± 0.5cm. For second freeze cycles of 10-15 minutes, the dimensions were 4.8 ± 0.7cm × 3.4 ± 0.5cm × 3.2 ± 0.4cm. The mean volume of the ice ball was 30.5 ± 11.2mm3 and 33.2 ± 3.4mm3 respectively.

All patients very well tolerated the freeze-thaw procedures, which took approximately a total of 30-45 minutes. No patients had postprocedural pain requiring narcotic pain medications, and there were no significant complications from the procedure.

All 27 patients who were successfully treated underwent lumpectomy an average of 14 days after the cryoablation (range, 8 to 35 days). Twenty-two of 27 patients had axillary staging by intraoperative lymph node mapping and sentinel lymph node biopsy performed at the same time. Four (14.8%) patients had a positive sentinel lymph node. The cryoablation had no effect on the subsequent interpretation of the sentinel lymph node.

No viable invasive cancer was discovered in 23 (85.2%) of the 27 patients according to histological findings of specimen from lumpectomy. A ductal carcinoma-in-situ (DCIS) which was present within the normal tissue surrounding the cryozone was discovered in an additional four patients (14.8%), in whom two patients had a small focus of lesion and two cases had multifocal lesions. The efficacy of cryoablation was estimated in term of no residual cancer cells was correlated with tumor size. Among eleven patients whose tumors <15 mm in size successfully underwent cryoablated, with no residual invasive or intraductal carcinoma, whereas the tumors in 4 patients with residual DCIS had 15, 21, 21 and 25mm in size respectively.

Conclusion

Cryoablation is a safe and well-tolerated procedure for the ablation of small solitary breast cancer. At present, cryoablation should be limited to patients with invasive ductal carcinoma less than 15mm.