Pain is one of the common symptoms experienced by patients suffering from malignant tumours. It is due to compression of the tissues, nerve endings and nerve trunk by infiltration, metastasis and dissemination of tumour cells. Management of pain is one of the key aspects of cancer treatment. Dr. Kathleen Foley pioneered the establishment of a pain clinic in America specialising in the treatment and support of people with serious or terminal illness. She maintained “Death is inevitable but severe suffering is not”. In 1979, Foley and her colleagues rated the severity of pain associated with different types of cancer. For example, the pain of primary bone cancer is rated at 85%, oral cancer at 80%, urino-genital cancer at 70%, breast cancer at 52% and lung cancer at 45%. Based on investigations conducted in Shanghai, China between 1987 and1990, rates of cancer-related pain were reported as follows: liver cancer (79%); pancreatic cancer (61%), lung cancer (54%), kidney cancer (48%), breast cancer (30%) and recurrent bone marrow cancer (60%). In developed countries, it was estimated that satisfactory relief is not obtained for some 50-80% of cancer-related pain.
Theory of CNS Sensitisation 中枢敏感化理论
Persistent, pernicious pain stimuli will lead to increases CNS excitability. Increased excitability gives rise to a heightened sensation of pain: by lowering the pain threshold it gives rise to a heightened sensation of the pain. Persistent, non-damaging stimuli also lower the pain threshold and lead to sensitisation of the pain stimuli.
Special Characteristics of CNS Sensitisation
- Once established, increased sensitivity of the CNS can be irreversible.
- Pre-pain suppressors (also known as advanced pain suppressors or pre-emptive analgesia) incorporate the administration of analgesics in anticipation of an episode of pain. This protocol is effective in minimizing the optimum dosage.
- Early treatment anticipating the pain is both appropriate and effective.
Repetitive stimulation of C-fibres can lead to an excessive electrical charge in the anterior horns generated by the spinal anterior horn neurons. Subliminal stimuli enable the nerve cells to produce a supraliminal stimuli reaction thereby reducing the pain threshold. This is because substances such as prostaglandins, K+ and 5-HT, bradykinins and histamines are released locally, lowering the the pain threshold and increasing the sensation of pain. Animal studies suggest that opioid-like substances can reduce pre-synaptic neurotransmitter release with concomitant depolarisation of the dorsal horn neurons, thereby reducing the CNS response to pain stimuli. In humans it has been found that the administration of a local anaesthetic prior to general anaesthesia at the time of surgical procedures results in greater pain relief post-operatively than when general anaesthesia is used alone, resulting in a reduction in the need for analgesics use post surgery. The effect can last up to 10 days.
Difficulties associated with the administration of pre-pain suppressors in Western medicine
- The administration of analgesia for patient without pain is considered unethical.
- Side effects of analgesic medication (vomiting, constipation, etc)
- Increased financial burden to the patient or the health system
Study on pre-pain suppressors in male patients with Stage III liver cancer
Potential for administration of Chinese medicine as a pre-pain suppressor
- Chinese materia medica and formula books have no analgesia category and therefore there is no ethical dilemma
- Side-effects are few and insignificant when compared with Western analgesic drugs.
- Concept of “preventative” medicine is embraced by Chinese medicine
- There is a double regulatory effect of a) maintaining balance and thus indirectly preventing CNS sensitivity, and b) increasing resistance to any adverse effects of Western medication.
Chinese medicine emphasis on unblocking and supplementing
Yi Xue Zhen Chuan医学真传 (True Transmission of Medicine) states: “If there is no obstruction, there is no pain. There are many ways to free obstruction which include regulating qi to harmonise blood, regulating blood to harmonise qi, redirecting counterflow, dispersing constraint;supplementingdeficiency, warming the channels, and dispersing cold. The aim of all these is to unblock.”
Herbs which invigorate blood: Pu Huang, Xue Jie, Chuan Xiong, Dan Shen, Dang Gui are anti-coagulant and minimise tissue hypoxia, which is the modern medical equivalent of moderating pain by alleviating blood stasis.
Herbs which nourish liver and calm the shen: By alleviating anxiety, fright, depression and insomnia, they raise the pain threshold.
- Xiao Yao San (Chai Hu, Shao Yao, Yu Jin, Xiang Fu)
- Gui Pi Tang (Ren Shen, Fu Shen, Zao Ren, Yuan Zhi etc.)
- Sun Ten Formula: Xiao Yao San (Bupleurum & Gang Gui Formula)
- Sun Ten formula: Gui Pi Tang (Ginseng & Longan Combination)
Herbs which replenish zheng qi: Ren Shen and Gan Cao reduce substance P in the serum and the tumor, increase cerebral ACh (acetylcholine), ß-endorphins and numerous enkephalin, thus effectively inhibiting pain transmission.
Herbs which regulate qi: Wu Yao, Yuan Hu, Ru Xiang, Mo Yao, Bing Pian have been shown in animal studies to raise the pain threshold and reduce the body’s reaction to pain stimuli.
Research has shown that Shao Yao Gan Cao Tang is effective in suppressing and moderating pain caused by muscular cramps and spasm.
Qiu Jia Xinand colleagues conducted a study on diethylnitrosamine-induced liver cancer in rats. Post surgery, the control group of rats suffered from restlessness, vexation and flank tenderness. In the treatment group the symptoms were significantly reduced and Chinese medicine was found to be effective.
The principle of relieving pain by unblocking
- Qi invigorating herbs: Wu Yao, Chuan Lian Zi, Li Zhi He, Chen Xiang.
- Blood invigorating herbs: Yuan Hu Suo, Xue Jie, Ru Xiang, Mo Yao, Wu Ling Zhi, Liu Ji Nu.
- Blood and Qi invigorating herbs: Yu Jin, Jiang Huang, San Leng, E Zhu.
Formulas which move qi
- Nuan Gan Jian: Dang Gui 6g; Gou Qi Zi 9g; Xiao Hui Xiang 6g; Rou Gui 3g; Wu Yao 6g; Chen Xiang 3g ; Fu Ling 6g
Action: Warms the liver and kidney and eases pain in the lesser abdomen.
- Sun Ten formula: Dang Gui Shao Yao San (Dang Gui & Peony Formula)
- Jin Ling Zi San: Jin Ling Zi 30g; Yuan Hu 30g
Action: Relieves constrained heat and eases pain in the chest and abdomen.
Formulas which invigorate blood
- Xue Fu Zhu Yu Tang: Tao Ren 12g; Hong Hua 9g, Dang Gui 9g; Sheng Di Huang 9g, Chuan Xiong 5g; Chi Shao 6g; Niu Xi 9g; Jie Geng 5g; Chai Hu 3g; Zhi Qiao 6g; Gan Cao 3g
Action: Moves qi and blood, eliminates stasis in the chest, eases chest pain and headache.
- Sun Ten formula: Shu Jing Huo Xue Tang (Clementis & Stephania Combination)
- Shi Xiao San:An equal dosage of Wu Ling Zhi and Pu Huangground into powder. 6g to be taken with water
Action: Eliminates stasis and eases pain in the heart and abdomen
- Tong Kuai Xiao Kou Fu Ye 痛块消口服液: Xiang Fu, Chuan Xiong, Dang Shen, Fu Ling, Ju Hua, Mei Gui Hua, Bai Shao, Gan Cao, Bai Hua She She Cao etc.
Action: Disperse constrained liver qi, invigorate blood transform stasis, nourish blood and liver, and soften hardness and dissipate knotted bind.
This article was first published at the Pearls of Wisdom Seminar in July 2007
About Professor Li Pei Wen
Professor Li Pei Wen is one of China’s leading oncologists in Chinese Medicine. He has more than 35 years of clinical and research experience in the prevention and treatment of cancer using integrated Western and Chinese medicine. From 1981 to 1984, he… Read more »