Short introduction
Cryosurgery is a novel technique for treatment of cancer which has been approved by the United States' Food AND Drug Administration (FDA) in 1998 and China's SFDA in 1999. Fuda Cancer Hospital-Guangzhou has used the technique since 2000. To date, Fuda has the greatest amount of experience in this minimally invasive operation; often Fuda trains doctors from around the world on the cryosurgery technique. Recently, Fuda's number of cryosurgery cases has nearly topped 5,000 cases with a variety of malignant tumors (more than 34 different kinds of cancers). In this field, Fuda Cancer Hospital leads the world in experience and research. Principle Cryosurgery is an important ablation technique for tumors. It destroys tumors by cycles of freezing and thawing. Cryosurgery's destructive effects on tumors are due to two major mechanisms, one immediate, the other delayed. The immediate mechanism is the damaging effect of freezing and thawing the cells. The delayed mechanism is the progressive failure of microcirculation; ultimately, vascular stasis becomes operative as an important cause of tumor tissue destruction. Once the temperature falls below -40oC, ice crystals may form within the cells. Once it occurs, cell death is almost certain. During cryosurgery, progressive failure of microcirculation occurs due to a cascade of events: endothelial layer destruction causing vessel walls to become porous, interstitial edema, platelet aggregation, microthrombii, and ultimately vascular congestion and obliteration. It was theorized that during cryosurgery, the immune system of the host became sensitized to the tumor being destroyed by the cryosurgery. Any primary tumor tissue undamaged by the cryosurgery and the metastases were destroyed by the immune system after cryosurgery. This response was termed the "cryo-immunological response". Procedure of cryosurgery Cryosurgery is performed through intraoperative, endoscopic or percutaneous routes depending upon the location and size of tumor.
Cryoablation is performed by using argon-helium system. Two to three cycles of the freezing/thawing are performed. The freezing continues until the "ice-ball" formed at the tip if the cryoprobe is large enough to cover tumor. A 5-10 mm margin of normal tissue is included in the freezing process. For larger tumors, multiple cryoprobes were used. In some cases, it may become necessary to perform at least 2-3 sessions of the cryoablation procedure. This is possible because the procedur0e is minimally invasive, and often does not require cutting. The probes are simply inserted through the skin and guided by real-time ultrasound.
Advantages- Cryosurgery is a localized medical procedure. It can be used as the sole means of cancer treatment or it can be combined with other conventional treatment techniques such as surgical operation, chemotherapy, radiotherapy.
- Combining cryosurgery with excision can be advantageous since freezing the tumor before excision minimizes the risk of spreading the cancerous cells during excision