With the development of industry and the consequent deterioration of the environment (water, air and food), the incidence of cancer is becoming younger and is gradually increasing, and cancer pain is one of the main causes of suffering for patients with advanced cancer. At this stage, patients are in considerable physical and mental pain; 80% of advanced cancer patients suffer from severe pain, and according to statistics, tens of millions of people in the world suffer from pain every day. Cancer pain has become an important object of daily work of relevant departments, especially an important part of pain department treatment.
However, there are still many areas for improvement in the management of cancer pain, including the unsatisfactory effect of treatment, the side effects of treatment, and the abuse of opioids. The World Health Organization’s goal of “pain-free cancer pain patients by the year 2000” is far from being achieved in China. As a pain professional, pain doctors should lead clinical departments to improve the control of cancer pain and return cancer patients to a pain-free life or even a pain-free life.
The goal of cancer pain control: is to eliminate pain, control the adverse effects of drugs, minimize the psychological burden and maximize the quality of life. Cancer pain treatment is an important part of cancer treatment. The purpose of treating cancer pain is to bring back the balance in the patient’s body and let him return to normal life, and standardized cancer pain treatment has no effect on the function of somatic sensation of normal pain. Some studies have shown that comprehensive cancer pain treatment will help prolong the survival of patients.
Diagnosis of cancer pain is the basis of correct treatment of cancer pain. Through diagnosis, clinicians can have an all-round understanding of the patient, which provides a good basis for the formulation of individualized treatment plan. The reason why many clinical patients have poor results in cancer pain treatment is mostly due to the lack of serious diagnostic assessment and hasty treatment.
In clinical practice, benign tumors grow mainly by expansion. It only produces compression and obstruction to the local organs. In contrast, malignant tumors invade adjacent tissues and organs and destroy their structures and functions. It can not only grow and expand in the primary site, but also spread directly to the adjacent tissues. In addition, malignant tumors can also metastasize to distant parts of the body through many ways. When tumor compresses or invades nerves, blood vessels and intestines, it can produce pain in addition to functional changes of corresponding tissues and organs.
Cancer metastasis to vertebrae or ribs, invasion of spinal nerve roots or intercostal nerves, and cancer infiltration to pleura, peritoneum or periosteum can all produce severe pain. After cancer extends to cavity organs, pain is often accompanied by nausea and vomiting. The common sites of cancer pain are chest and back, head and neck, abdomen, pelvis, bones and chest. In addition to the above-mentioned causes, surgical treatment and radiation therapy can also cause new pain areas or form new sources of pain.
Generally speaking, patients with intractable and severe pain are usually in the advanced stage of cancer, although there are exceptions. Since pain has a great impact on the patient’s body and mind, the change of the patient’s body and mind will aggravate the deterioration of the whole body, thus forming a vicious circle. On the contrary, after effective analgesic treatment for cancer pain patients, the patients’ general condition improves significantly, especially their emotion turns better, thus their diet increases and their confidence in treatment is enhanced, which prolongs their lives.
Cancer pain is not pain in the general sense; it is a complex and special type of pain, and a mixed pain in which multiple pains are mixed. The term total pain, coined by Dame Cicely Saunders, emphasizes that advanced cancer pain is the result of multiple factors, including physical, psychological, social and spiritual factors. Cancer patients sometimes describe their lives as painful. Thus, if those caring for the patient are to speak of all aspects of discomfort and distress when pain is about to be relieved, while the clinician may have the ability to distinguish between all aspects of “pain of life,” the patient often does not, and for him the pain is all-encompassing and all-encompassing.
When cancer pain occurs, it often progresses and worsens, and patients will be extremely frustrated if the analgesia is not effective in their treatment. They will recognize that the clinician is unable to effectively stop the pain. After weeks or months of pain, especially when accompanied by insomnia, many cancer patients are subdued by pain that envelops their entire mental field of vision, and such patients often find it difficult to precisely depict the location or nature of the pain.
In most patients with cancer pain, the response to persistent pain is vegetative, and the patient is mentally and physically withdrawn and appears depressed. In some patients, anxiety predominates, or anxiety and depression are mixed together and coexist. In all cases of overwhelming pain, there is a vicious cycle of “insomnia → fatigue → pain → insomnia”.
When diagnosing cancer pain, not only psychological evaluation but also psychological support needs to be initiated. When anxiety is prominent, treatment should include analgesics and anxiolytics, the choice and dosage of each drug being largely determined by what drugs the patient has taken previously. Overwhelming pain with significant anxiety is best viewed as an emergency that requires significant time for treatment.
Patients may have both significant anxiety and pain, and the pain is not overwhelming. When the pain subsides, moderate anxiety usually subsides and the patient speaks of fear and worry. The use of psychological assessment scales helps to quantify the patient’s depression or anxiety. We commonly use the Self-Rating Scale for Depression (SDS) and the Hamilton Anxiety Inventory (anxiety scale) to evaluate the psychological status of patients. It was observed that about 91.3% of oncology patients experienced varying degrees of psychological disturbance after knowing they had cancer, with higher anxiety scores and depression scores than the norm.
Suffering and pain exist at the same time
Pain and distress are not exactly the same; therefore, distress must be distinguished from pain and other symptoms that may be associated with it. Patients can tolerate severe pain without thinking about the pain they are going to suffer if they know that there is a definite cause for the pain, that the pain is manageable, and that the pain will be relatively short-lived. On the other hand, if patients believe or know their true condition, even relatively mild symptoms can cause pain, they have a life-threatening cause, they are intractable, and they reflect a hopeless prognosis.
The impact of cancer on patients is often devastating, suffering can be caused by both the disease and its treatment, and pain is not limited to somatic symptoms. To determine the source of suffering, patients need to be evaluated psychologically and asked unresolved questions. Suffering extends to threats to all aspects of social and private life. The pain is experienced both in terms of the impact of the disease and treatment on appearance and various abilities, as well as in terms of the patient’s understanding of the future.
Social pain means pain associated with anticipated or actual separation, or loss. Patients with cancer pain are often aware that they will be separated from their families by death. Therefore, it is important to take steps to avoid all the things that separate patients with advanced cancer from their family and friends. Allowing visits from the patient’s grandchildren and children may provide more effective pain relief than increasing the dose of opioids.
Psychogenic pain
Patients with cancer have constant pain. This pain and the prospect of death create great apprehension and anxiety, and the role of any one person or treatment in palliative care is generally not so exciting. However, the basic idea remains the same, that is, cancer pain is a somatic-psychic sensation, and that the effects of cancer pain on various non-somatic aspects, especially on the psychiatric aspects, must be taken into account. Cancer pain causes changes in the mental aspects of patients, and the pain becomes more complicated.
Cancer pain is a subjective experience, and quantitative analysis of this subjective feeling is necessary for clinical work. Measuring the intensity and range of pain and its changes are directly related to the classification of patients’ diagnosis, selection of treatment methods, observation of disease, evaluation of treatment effects and research work about pain, which is the basis of effective treatment of cancer pain. Although there are many methods to quantitatively measure pain, they all rely on patients’ subjective description of pain experience, with a certain degree of subjectivity, while lacking objective indicators.
Numerous clinical studies on visual analog scoring method have proved that VAS has the following advantages in pain assessment.
1. It can effectively determine the intensity of pain. Previous studies have shown good correlation between VAS and other pain intensity monitoring methods.
2. Most patients find the VAS easy to understand and use, even in children (<5 years old).
3. The scores are evenly distributed.
4. The scoring can be repeated at any time.
5.Compared with the oral pain scoring method, the visual analog scoring method is more satisfactory for assessing the effect of pain treatment.
6.It can provide satisfactory results on the diurnal variation of pain disorders, the difference between pain disorders and the time and process of treatment effects.
Since cancer pain seriously affects patients’ quality of life, when evaluating its intensity, it can also be combined with medication taking and quality of life to better judge the degree of cancer pain. The intensity of cancer pain is generally divided into three levels: mild, moderate and severe.
Mild (Grade I): pain is tolerable but can live normally and sleep is not affected.
Moderate (Grade II): pain is obvious and unbearable, requiring analgesic drugs and sleep is disturbed.
Severe (Grade III): pain is severe and unbearable, requiring analgesic drugs, sleep is seriously disturbed, and may be accompanied by plant nerve dysfunction or passive body position.
Distribution of cancer pain
When evaluating the pain of cancer patients, attention should be paid to asking patients about the distribution of pain areas. The distribution of pain areas can provide clues for diagnosis and treatment. Distinguishing between localized, multiple and generalized pain is important for choosing treatment methods, including nerve block, radiation therapy or surgery.
Patients also often have difficulty describing the site of pain and need the help of a clinician. Patients often do not know the medical terminology for how to express where the pain is located. The area indicated by the patient’s fingertip is often only the center of the painful area. A simple method commonly used in clinical practice is to provide the patient with a diagram with the outline of the body and ask him/her to draw the painful area on the corresponding part of the body outline.
Nature of cancer pain
The nature of cancer pain can be used as a reference for diagnosing the site of tumor. Somatic injury-receptive pain can be precisely localized, and the complaint is sharp, persistent, throbbing or tight pressure pain, which is a phenomenon of involvement of somatic nerves. Visceral injury-receptive pain is generally diffuse; spasmodic or bite-like pain in hollow organ obstruction; sharp, persistent or throbbing pain when the organ peritoneum or mesentery is invaded. Neuropathic pain caused by the involvement of peripheral nerve trunk or its branches is burning, pins and needles, radiating in certain directions or similar to pain caused by electric shock.
Cancer pain can be divided into two types: acute and chronic. Acute cancer pain is characterized by recent onset, short history, definite time of occurrence, and identifiable cause, such as gastritis caused by chemotherapy or headache caused by lumbar puncture. This pain may or may not be accompanied by obvious pain behaviors, such as moaning, painful expressions or the need for immobilization due to struggling, and signs of anxiety or generalized sympathetic hyperfunction, including sweating, elevated blood pressure and tachycardia. Chronic pain is defined as pain that lasts for 1 month or longer than the general course of an acute disorder or injury, or combined with chronic lesions that recur intermittently over several months or years in other chronic painful conditions. There are several types of cancer pain as follows.
1.Acute cancer pain
2.myofascial pain
Myofascial pain is the most common skeletal muscle disorder in the neck, shoulder girdle and lumbar region. Debilitated cancer patients suffer from myofascial pain several times higher than the general population.
3.Cancerous visceral pain
4.Neuropathic pain
Neuropathic pain is caused by dysfunction or injury of the peripheral nervous system (PNS) or central nervous system (CNS), and it can also be related to overactivity of the sympathetic nervous system. Neuropathic pain is almost always accompanied by altered sensation. This characteristic has led to the current definition of neuropathic pain, i.e. pain occurring in areas of abnormal or absent sensation.
Neuropathic pain is the currently accepted terminology. As mentioned earlier, neuropathy is defined as nerve dysfunction or pathological changes, and this definition focuses on dysfunction rather than injury, implying that persistent sympathetic pain is a form of neuropathic pain.
5.Nerve compression pain
6.Sympathetic persistent pain
Sympathetic persistent pain (SMP) is a less common sequelae of tissue injury or sympathetic nerve injury, with pain relief and reversal of sensory deficits after sympathetic blockade. Some authors suggest that SMP arises from sensitization of wide dynamic domain neurons within layer V of the posterior horn of the spinal cord and is pain caused by afferent fibers from mechanoreceptors (not injury receptors). Just like nerve injury pain, SMP may also have genetic susceptibility.
7. Bone metastatic pain
Bone metastasis from cancer is a common cause of bone pain, and lung, breast and prostate cancers are prone to metastasis to bone. Bone metastases cause bone pain by a variety of mechanisms, including activation of endosteal or periosteal injurious stimulus receptors caused by mechanical deformation or release of chemical mediators, and tumor extension to adjacent soft tissues or surrounding nerves. Although bone pain is common after bone metastasis, about 25% or more of patients with bone metastasis do not have pain, and sometimes multiple metastases but only l to 2 have painful symptoms.
Bone pain is the main reason why bone metastasis cancer attracts attention. Most bone metastases do not cause pain for a certain period of time. It is only when the disease progresses that pain gradually appears, and then the patient’s family starts to go to hospital for treatment. The causes of pain in bone metastases are multiple. They include localized pain in the bone, radiation to surrounding tissues, pulling pain, compression of nerves, muscle spasm and associated myofascial pain.