Breast Cancer Cryoablation: Assessment of the Impact of Fundamental Procedural Variables in an In Vitro Human Breast Cancer Model

Abstract

Introduction: Breast cancer is the most prominent form of cancer and the second leading cause of death in women behind lung cancer. The primary modes of treatment today include surgical excision (lumpectomy, mastectomy), radiation, chemoablation, anti-HER2/neu therapy, and/or hormone therapy. The severe side effects associated with these therapies suggest a minimally invasive therapy with fewer quality of life issues would be advantageous for treatment of this pervasive disease. Cryoablation has been used in the treatment of other cancers, including prostate, skin, and cervical, for decades and has been shown to be a successful minimally invasive therapeutic option. To this end, the use of cryotherapy for the treatment of breast cancer has increased over the last several years. Although successful, one of the challenges in cryoablation is management of cancer destruction in the periphery of the ice ball as the tissue within this outer margin may not experience ablative temperatures. In breast cancer, this is of concern due to the lobular nature of the tumors. As such, in this study, we investigated the level of cell death at various temperatures associated with the margin of a cryogenic lesion as well as the impact of repetitive freezing and thawing methods on overall efficacy. Methods: Human breast cancer cells, MCF-7, were exposed to temperatures of −5°C, −10°C, −15°C, −20°C, or −25°C for 5-minute freeze intervals in a single or repeat freeze-thaw cycle. Samples were thawed with either passive or active warming for 5 or 10 minutes. Samples were assessed at 1, 2, and 3 days post-freeze to assess cell survival and recovery. In addition, the modes of cell death associated with freezing were assessed over the initial 24-hour post-thaw recovery period. Results: Exposure of MCF-7 cells to −5°C and −10°C resulted in minimal cell death regardless of the freeze/thaw conditions. Freezing to a temperature of −25°C resulted in complete cell death 1 day post-thaw with no cell recovery in all freeze/thaw scenarios evaluated. Exposure to a single freeze event resulted in a gradual increase in cell death at −15°C and −20°C. Application of a repeat freeze-thaw cycle (dual 5-minute freeze) resulted in an increase in cell death with complete destruction at −20°C and near complete death at −15°C (day 1 survival: single −15°C freeze/thaw = 20%; repeated −15°C freeze/thaw = 4%). Analysis of thaw interval time (5 vs 10 minute) demonstrated that the shorter 5-minute thaw interval between freezes resulted in increased cell destruction. Furthermore, investigation of thaw rate (active vs passive thawing) demonstrated that active thawing resulted in increased cell survival thereby less effective ablation compared with passive thawing (eg, −15°C 5/10/5 procedure survival, passive thaw: 4% vs active thaw: 29%). Conclusions: In summary, these in vitro findings suggest that freezing to temperatures of 25°C results in a high degree of breast cancer cell destruction. Furthermore, the data demonstrate that the application of a repeat freeze procedure with a passive 5-minute or 10-minute thaw interval between freeze cycles increases the minimal lethal temperature to the −15°C to −20°C range. The data also demonstrate that the use of an active thawing procedure between freezes reduces ablation efficacy at temperatures associated with the iceball periphery. These findings may be important to improving future clinical applications of cryoablation for the treatment of breast cancer.

Silver Nanoparticles: An Instantaneous Solution for Anticancer Activity against Human Liver (HepG2) and Breast (MCF-7) Cancer Cells

“…The occurrence of breast cancer is much higher than any of these other types of cancer [20]. To eradicate the cancer from the body, various therapies have been tested, such as chemotherapy [23], hormone therapy [24], radiotherapy [25], immunotherapy [26], stem cell therapy [27], proton beam therapy [28], clinical trials [29], and cryoablation [30], etc. Surgery is also an option to remove the cancer cells from a specific organ in the body [31].…”

Feasibility and Safety of Single-Probe Cryoablation with Liquid Nitrogen: An Initial Experience in 24 Various Tumor Lesions

“…Three-cycle protocols were chosen for lung lesions, as previously described in the literature [ 11 ]. A previous study showed that the thawing process (both active and passive) did not impact tissue damage [ 19 ], but more recent studies have demonstrated that active thawing resulted in increased cell survival, and thereby less effective ablation, as compared with passive thawing [ 20 ]. In our study, passive thawing was performed.…”

Inhibition of aquaporins as a potential adjunct to breast cancer cryotherapy

“…In addition, 0°C degree was used as the control temperature for non-freezing conditions. Freezing for 10 min was the time necessary for the media to be frozen while preserving the integrity of the cells ( 53 ). A temperature of 0°C was achieved by placing the cells on a MyBlock™ Mini dry bath with cooling (Benchmark Scientific, Inc.) and −13°C temperature was achieved by placing the cells in a Sanyo temperature calibrated freezer (Sanyo Electrical Co. Ltd.), while the control temperature was achieved by maintaining the cells in a humidified 5% CO 2 atmosphere at 37°C.…”

“…The lowest temperature that could be used to accomplish freezing while maintaining cell viability was -13˚C. In a previous study, a temperature of -10˚C resulted in a high cell survival rate, whereas -15˚C led to >80% cell death (53). In addition, 0˚C degree was used as the control temperature for non-freezing conditions.…”