Sunday, December 6, 2009

Cryosurgery treatment for Cancer

Cryosurgery abides a novel method for treatment of cancer which has been accepted by the united states' food & drug administration (FDA) in 1998 also China's SFDA in 1999. Fuda cancer Hospital-Guangzhou has applied the method since 2000. To date, Fuda has the best amount of experience in this minimally invasive operation; usual 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, microthrombi, 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 procedure 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

  • In addition to sparing healthy tissue, cryosurgery is advantageous because it is not dose-limited can be repeated as necessary in order to destroy all cancerous tissue

  • In situations where the tumor is not removed after freezing, especially percutaneous cryosurgery, operative blood loss is small and post-surgical discomfort is minimized

  • Cryoprobes are relatively small (generally in the range of 24 mm in diameter) and therefore they may be used in minimally in-vasive surgical procedures

  • There are no major side effects which are commonly found in chemotherapy or radiotherapy

  • Cryosurgery is adaptable for treatment of tumor close to large vessel which cannot be removed by operation

  • Cryosurgery can treat small as well as large tumors, and solitary as well as multiple tumors

  • Cryosurgery per se aims at a local effect, namely, destruction in situ of neoplasms resistant to conventional treatments, but it also elicits an immunologic reaction (cryoimmunologic reaction) against cancer for eradication of residual or metastatic tumors

  • There is evidence that the recurrence rate of cancer after cryosurgery is lower than that of operation

Indication

Nearly all parenchymal cancers are prime candidates for cryoablation.

These malignancies include:

*Liver cancer
*Lung cancer(non-small cell lung cancer)
*Kidney cancer
*Ovarian cancer
*Pharyngeal cancer
*Testicular cancer
*Uterine tumors
*Vaginal cancer
*Pancreatic cancer
*Breast cancer
*Sarcoma and other benign or malignant lesions of bone
*Prostate cancer
*Skin cancer and melanoma
*Head and neck cancer
*Tumor of soft tissues

In addition, cryosurgery can be an effective treatment for the following:

* Retinoblastoma (a childhood cancer that affects the retina of the eye).
*Early-stage skin cancers (both basal cell and squamous cell carcinomas)
*Precancerous skin growths known as actinic keratosis.
*Pre-cancerous conditions of the cervix known as cervical intraepithelial neoplasia (abnormal cell changes in the cervix that can develop into cervical cancer).


For More information Visit:Fuda Cancer Hospital-Guangzhou


No comments: