In a small but promising Phase II clinical trial of breast cancer treatment, cryoablation killed 25 early-stage tumors in 13 women. The tumors ranged in size from .5 cm (very small) to 5.8 cm (very large), with an average size of 1.7cm. Patients were first given a local anesthesia with mild sedation before physicians used ultrasound with or without computed tomography (CT) imaging to guide needle-like probes to deliver very low temperature gas to the tumor site. The ultra-cold gas forms a ball of ice around the probe tip, then expands and destroys surrounding tumor cells. A harmless saline solution was first injected into the chest wall and skin of the breast to protect the tissue surrounding the tumor from the freezing effects.
Patients experienced very little pain and most healed completely within six months with no complications and with little or no scarring. The cryotherapy margins of each participant were biopsied immediately after the procedures, and all were negative, with no evidence of cancerous tissue. All 13 patients were without recurrence at an average of 18 months and up to five years following the procedure.
These results are promising, but larger studies with lengthier follow-up are needed to determine whether cryotherapy as effective as lumpectomy.
A study involving cryoablation of mouse tumors at the University of Michigan Comprehensive Cancer Center found that the freezing procedure also works like a vaccine, boosting the immune system to reduce the likelihood of recurrence. Just how quickly the tumor was frozen made a difference: a 30-second freeze killed tumors and also boosted the immune system, inhibiting metastases to the lungs. A slower freezing lasting several minutes destroyed tumors just as effectively, but actually suppressed the immune system, resulting in greater metastases to the lungs.