Monday, March 14, 2011

Surgery-Induced Cancer Metastasis - Part 4

The Choice of Surgical Anesthesia Can Influence Metastasis
The conventional medical approach to surgical anesthesia has been the use of general anesthesia during surgery, followed by intravenous morphine after surgery for pain control. The use of morphine directly after surgery surpresses the immune function thereby by diminishing NK cell activity. One study found that morphine increased angiogenesis and stimulated the growth of breast cancer in mice and concluded: that clinical use of morphine could potentially be harmful in patients with angiogenesis-dependent cancers.

One novel approach to minimise the above problems is to combined with regional anesthesia, which refers to anesthesia that only affects a specific part of the body. The benefits achieved with this approach are two-fold: the use of regional anesthesia reduces the amount of general anesthesia required during surgery, as well as decreasing the amount of morphine needed after surgery for pain control. This elegant approach to surgical anesthesia and pain control has been validated in scientific mice studies. Regional anesthesia reduced 70% of the metastasis-promoting effects of surgery caused by general anesthesia alone.

Doctors at Pennsylvania State University College of Medicine compared NK cell activity in patients, NK cell activity was preserved at pre-operative levels in the group that received regional anesthesia. In a pioneering study, 50 women having breast cancer surgery using general anesthesia with regional anesthesia (the type of regional anesthesia used is called a paravertebral block, which involves the injection of a local anesthetic around the spinal nerves between the vertebral bones of the spine) after a follow-up period of nearly three years shows only 6% of patients experienced a recurrence, compared to 79 women who received general anesthesia during their breast cancer surgery followed by morphine for pain control showed a 24% risk of recurrance for this group. Stated differently, women who received regional and general anesthesia had a 75% decreased risk for metastatic cancer.

Surgeons at Duke University Medical Center compared regional anesthesia alone to general anesthesia in women having surgery for breast cancer noted while 39% of the general anesthesia group required medication for nausea and vomiting, only 20% of the regional anesthesia group needed this medication. Narcotic medication was needed for pain control after surgery in 98% of the general anesthesia group, compared to only 25% of the regional anesthesia group. And 96% of the women receiving regional anesthesia had returned home within a day after surgery, compared with 76% of the women who received general anesthesia.

The results of these studies have vast implications for those undergoing cancer surgery, as a group of researchers enthusiastically announced: As regional techniques [anesthesia]are easy to implement, inexpensive, and do not pose a threat greater than general anesthesia, it would be easy for anesthesiologists to implement them, thus reducing the risk of disease recurrence and metastasis. For those requiring morphine for pain control after surgery can consider asking their doctor for a medication called tramadol instead. In one experiment, tramadol blocked the formation of lung metastasis induced by surgery in rats. Tramadol also prevented the surgery-induced suppression of NK cell activity.

Less Invasive Surgery Reduces Risk of Metastasis
Surgery places an enormous physical stress upon the body. There is considerable scientific evidence supporting that surgeries that are less invasive and therefore less traumatic pose less risk of metastasis. Laparoscopic surgery is one type of minimally invasive surgery, in which operations in the abdomen, pelvis, and other regions are performed through small incisions.

A study published in the prestigious medical journal The Lancet compared laparoscopic to open surgery to remove part of the colon (colectomy) in patients with colon cancer found that the group had a 61% decreased risk of cancer recurrence coupled with a 62% decreased risk of death from colon cancer as compared to the group receiving traditional open surgery. A long-term follow-up of these patients (median time 95 months) reported a 56% decreased risk of death from colon cancer for laparoscopic surgery as compared to traditional open surgery. Another comparison of laparoscopic surgery to open surgery for colon cancer reported a five-year survival rate of 64.1% for the laparoscopic group, and a five-year survival rate of 58.5% for the group receiving open surgery.

Minimally invasive surgery has produced substantial improvements in survival for those with lung cancer. Video-assisted thoracoscopic surgery (VATS), a minimally invasive surgery, was compared to traditional open surgery for removing lung tumors (lobectomy). The five-year survival from lung cancer was 97% in the VATS group. This greatly contrasts the 79% five-year survival in the open surgery group.

Inflammation and Metastasis
Cancer surgery causes an increased production of inflammatory chemicals, such as interleukin-1 and interleukin-6. These chemicals are known to increase the activity of cyclooxygenase-2 (COX-2). A highly potent inflammatory enzyme, COX-2 plays a pivotal role in promoting cancer growth and metastasis. COX-2 fuels cancer growth by stimulating the formation of new blood vessels feeding the tumor.

Experiments in mice revealed that colon cancer cells expressing high levels of COX-2 metastasized freely to the liver, while colon cancer cells expressing low levels of COX-2 did not metastasize to the liver. the journal Clinical Cancer Research in 2004. Two hundred eighty-eight individuals undergoing surgery for colon cancer had their tumors examined for the presence of COX-2. The findings were alarming when other factors were controlled for, the group whose cancers tested positive for the presence of COX-2 had a 311% greater risk of death compared to the group whose cancers did not express COX-2. A subsequent study in lung cancer patients found that those with high tumor levels of COX-2 had a median survival of only 15 months, whereas those with low tumor levels of COX-2 had a median survival of 40 months.

Researchers began investigating the anti-cancer effects of COX-2 inhibitor drugs such as Celebrex. Celebrex dramatically prolonged survival in lung cancer cases and also slowed cancer progression in men with recurrent prostate cancer.

Non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, are COX inhibitors. The widespread use of NSAIDs for pain and arthritis has created an ideal environment in which to examine if these drugs can prevent cancer. Large-scale studies have documented a substantial reduction in cancer risk with the use of NSAIDs. A comprehensive review of the scientific literature (91 published studies) reported that the long-term use of NSAIDs (primarily aspirin) produced risk reductions of 63% for colon cancer, 39% for breast cancer, 36% for lung cancer, 39% for prostate cancer, 73% for esophageal cancer, 62% for stomach cancer, and 47% for ovarian cancer. This review provides compelling evidence that regular intake of NSAIDs that block COX-2 protects against the development of many types of cancer, the authors concluded.

A number of nutritional and herbal supplements are known to inhibit COX-2. These include curcumin, resveratrol, vitamin E, soy isoflavones (genistein), green tea (EGCG), quercetin, fish oil, garlic, feverfew, and silymarin (milk thistle). Scientists at Memorial Sloan-Kettering Cancer Center in New York created an experimentally-induced increase in COX-2 activity in human breast cells, which was completely prevented by resveratrol. Resveratol blocked the production of COX-2 within the cell, as well as blocking COX-2 enzyme activity.

Acknowledgment: These series of articles are abridged from the article Preventing Surgery-Induced Cancer Metastasis by Steven Nemeroff, ND.

To be continued (Part 5 - Conclusion).

1 comment:

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