Chemoemobilization

Chemoemoblization is the treatment of an already developed cancerous tumor by directly injecting anticancer drugs (chemotherapy) into the blood vessels feeding the tumor. Chemoembolization is not a cure, but rather a treatment that reduces the severity of symptoms, temporarily improving the quality of life and potentially extending survival. Presently, chemoembolization is primarily used for the treatment of liver tumors which, because of size and location, are often inoperable.

The procedure is based on stopping tumor growth by restricting the blood supply to the tumor while at the same time directing a large dose of medication specifically into the tumor. This procedure permits a high concentration of anticancer drugs to be administered into and remain in the tumor for a long period of time, thereby increasing its effectiveness. This directed method of delivery is called an “embolus” and is achieved by use of a catheter tube. This embolus approach allows the ability to focus treatment on the cancerous cells while protecting the rest of the body from chemotherapy exposure.

Chemoembolization is a minimally invasive procedure performed in a hospital under radiology guidance. The use of x-ray procedures allows for the identification of which vessels feed the targeted tumor. While specifics depend on the target vessels, the average treatment requires conscious sedation (patient is awake, but drowsy and numb), lasts about three hours, and requires an overnight stay in the hospital. Multiple treatments are often necessary with three being the average, usually performed over a period of months. Depending on the specifics of the cancer, chemoembolization may sometimes be combined with other treatments.

Chemotherapy drugs have side effects including hair loss, nausea, and anemia. The chemoembolization procedure includes additional risks such as possible infection after the procedure, and the possibility of affecting normal tissue by the embolus lodging in the wrong place. The radiology aspect of the process also poses potential risks including allergic reaction to the dyes used.

Chemoprevention

Chemoprevention is the attempt at preventing or halting cancer development, rather than treating developed cancerous tumors. This is a noninvasive approach that treats the changes that occur in cellular tissue prior to tumor development. While the medical community typically bases chemoprevention on pharmacologic intervention (or drug therapy), accepted treatments also include nutritional approaches and lifestyle modification. Current studies indicate that drug-based chemoprevention is useful only to high-risk individuals. However, nutrition-based chemoprevention can be utilized by all individuals.

The medical concept of chemoprevention is credited to Dr. Michael Sporn. In the 1970s, Dr. Sporn promoted the idea that cancer treatment should be targeted at preventing the development of cancerous tumors, rather than treating already developed tumors. He envisioned this prevention through the use of chemical compounds directed at the cellular changes associated with cancer. Dr. Sporn’s research was and is based on the belief that cancer is preventable if appropriate treatment is received before tumor development. However, this concept of chemoprevention is not targeted at the general population, but rather at high-risk individuals. High-risk individuals are those that have an increased risk of cancer due to diverse factors including heredity, dietary and lifestyle factors, as well as those with previous incidences of cancer.

In the 1980s the National Cancer Institute began to focus some studies on chemoprevention. Today, research of chemopreventive chemical compounds entails millions of dollars and multiple studies annually to develop and test new drugs. Approximately 400 compounds are currently being studied. Perhaps the most well known of these drugs is Tamoxifen used in breast cancer treatment.

The nutritional concept of chemoprevention bases tumor prevention on the use of certain foods and nutritional supplements including vitamins and minerals. Examples of preventative applications include the use of Vitamin D against colon cancer and the mineral Selenium against skin cancer. However, the research on nutritional chemoprevention is conflicting, with some studies showing risk reduction and others showing no effect. Research does indicate that nutrient combinations are more effective than single supplements. In addition to nutritional supplements, healthy lifestyle choices (such as regular physical activity) and avoidance of toxins (such as cigarettes) are recommended.

While the National Cancer Institute is pursuing studies focused on drug-based chemoprevention, they are only recommended for high-risk individuals. As for nutritional chemoprevention, the National Cancer Institute does not currently promote vitamin or mineral supplements for cancer prevention, but it does recommend a healthy diet and lifestyle.

As with all treatments, there are side effects. Because both the medical and nutritional approaches of chemoprevention require high doses of agents over long periods of time, they can cause unwanted effects. For example, drug treatments involving Tamoxifen have been associated with an increase in the risk of uterine cancer. Nutritional treatments involving Vitamin D have been associated with nausea, vomiting, mental changes, and other unwanted effects.

The American Association for Cancer Research has a scientific journal on cancer prevention research.