The treatment of breast cancer has evolved from the time of mutilation and ignorance in the middle ages, to one of breast conserving management and an intense study and understanding of the biological mechanisms driving tumor cells. As the treatment is directed to the cellular and sub-cellular level, breast conserving surgical procedures take on a more important role. Recent published results from neoadjuvant trials indicate a decrease in tumor size in 80% of patients and a modest increase in conversion from mastectomy to lumpectomy. By 2010 AD, it is estimated that 50% of all new breast cancers discovered will be less than 10 mm in diameter (Cady et al., 1996), which represents 90,000 patients. Standard surgical treatment would require an open segment resection, an operating room, anesthesia, cosmetic concerns and substantial cost. Add to this the number of patients who require segmental resection following complete clinical or pathological response following neoadjuvant chemotherapy, and the cost increases.
An alternative method of tumor removal or destruction for small malignancies is needed to complete the biological assault on breast cancer. Cryosurgery may be one of these alternative means. Cryosurgery has been used successfully for more than three decades to treat benign and malignant neoplasms. To date, there is one reported case of primary breast cancer treatment with cryotherapy (Staren et al., 1997), which was followed up with ultrasound-guided biopsy, and which was found negative for malignancy 12 weeks post-cryosurgery. Cryotherapy carries many benefits in addition to the attractive concept of minimally invasive surgery. Low temperatures generate anaesthetic effect. Hemorrhage is reduced due to thrombosis of small blood vessels. Cryotherapy may cause stimulation of the body’s immune system, which additionally augments local tumor destruction and may also induce a response in metastatic tumor sites (Suzuki, 1995).
With multiple treatments such as neoadjuvant therapy, hormone therapy, and radiation, which have the ability to downsize primary cancers and treat small cancers, lumpectomy may be increasingly used. Current diagnostic imaging trends are increasingly detecting small cancers (< 1 cm). The minimization of surgical intervention to compliment these trends is a natural progression of technology and understanding of the biological processes involved.
Our ongoing research program to evaluate cryosurgery in the breast is comprised of several phases: (i) development of a miniaturized cryoprobe and a cryodevice for minimally invasive breast cryosurgery; (ii) validation testing of the cryoprobe and device in vivo; (iii) development of a technique to evaluate the injury associated with cryotreatment of the breast; (iv) comparison of the ultrasound imaged “‘ice-ball” in vivo with the resulting cryoinjury immediately post-cryosurgery; and, (v) long-term follow-up post-cryosurgery in a recently-pregnant sheep breast model. The work to date is part of this report.