Role of Radiotherapy in Management of Cancer Pain P. Pradeep Kumar, MD Washington, DC
To a cancer patient, pain is a very distressing symptom and to the physician it heralds advanced nature of the disease. While the mechanisms of initiation of pain are simple, its perception is very complex. In cancer, the tumor growth which results in producing pressure, destruction of tissue, and obstruction is the main cause of pain production. Ionizing radiation, which checks tumor growth and shrinks the tumor most of the time, plays a major role in relieving pain in a cancer patient. Nearly 50 percent of all cancer patients receive radiotherapy at one time or other during the course of their disease. Pain is one of the major symptoms of all cancer patients seen in the radiotherapy department. Experiencing pain is the most distressing thing in one's life, and, as Sir Thomas Lewis stated, "pain defies a definition but the word would be understood by those who read about it because of past experience." After Descartes many years ago postulated the theory that pain perception was similar to ringing a church bell by pulling on one end of the rope, the other end of which is tied to the bell, other theories have been put forward to explain the neurophysiology of pain perception. Now we know that pain perception is not as simple as explained in the specificity theory, because after various neurosurgical procedures to relieve pain, if the patient survives long enough, the pain returns. Therefore, it is of vital importance to treat the cause of the pain as effectively
Requests for reprints should be addressed to Dr. P. Pradeep Kumar, Department of Radiotherapy, Howard University Hospital, 2041 Georgia Avenue NW, Washington, DC 20060.
as possible before attempting other indirect modalities of pain relief.
Origin of Pain in Cancer Patients The mechanism of origin and perception of pain in a cancer patient can be attributed to tumor and host factors. Host factors that influence this perception are psychologic, cultural, and protective-adoptive reactions of the patient to pain. In a cancer patient, the very thought of having the disease could initiate and/or precipitate pain. For this reason it sometimes becomes necessary to withhold the diagnosis of cancer from him/her. Those involved in the management of cancer patients know well enough that the ones from lower socioeconomic groups all over the world tolerate pain much better and require milder analgesics than those from higher socioeconomic groups. Development of protective adaptive reactions to pain in a cancer patient is a very important phenomenon in perception of the pain. Psychophysical therapy plays a very important role in helping one to develop such protective-adaptive reactions.
JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 71, NO. 3, 1979
The role of radiotherapy in relieving cancer pain is associated with tumor factors causative of pain. The four major tumor factors that are important in originating pain are infection, obstruction, destruction of tissue, and pressure.
Infection Infection of a tumor usually occurs following breakdown in the continuity of surface. The dead tumor tissue forms a good medium for growth of microorganisms. Infection is a common cause of pain in tumors of the upper and lower ends of the gastrointestinal tract, genitalia, and skin. Even though ionizing radiation has a sterilization effect on micro-organisms, the radiation dose required for this purpose is usually ten times greater than the dose given to a tumor, which is also the dose tolerated by normal tissue. Therefore, radiation does not play any role by direct action on the micro-organisms in relieving pain due to tumor infection. However, infection could occur, not in the tumor directly, but proximal to it, by blocking a normal drainage pathway. The best example of pain resulting from infection secondary to obstruction to normal drainage is flank pain due to kidney infection from carcinoma of the cervix obstructing the ureters (Figure 1). In many instances, pelvic irradiation relieves the mechanical obstruction and facilitates normal drainage, which clears the proximal infection and relieves pain (Figure 2). 279
/
Figure 2. VP of the same patient shown in Figure 1 after completion of external and intracavitary pelvic irradiation. The left kidney is seen functioning normally.
Figure 1. IVP of a patient with Stage IIIB carcinoma of the cervix showing nonfunctioning left kidney.
Obstruction Occlusion of a hollow viscus by a tumor causes severe colicky pain. Obstruction to arterial or venous blood flow gives rise to ischemic or congestive pain, respectively. The visceral pain is always referred to the corresponding dermatomes. In esophageal cancer (Figure 3) obstruction to food causes referred pain in the presternal region. Even though survival rates in patients with esophageal cancer are devastating, local irradiation shrinks the tumor, opens the obstruction and relieves pain in a great number of patients (Figure 4). An example of ischemic pain due to tumor is severe abdominal pain in patients with metastatic neoplasm to celiac nodes encasing the celiac axis. Local irradiation to the celiac nodes helps to reduce the encasement and relieves ischemic pain in a considerable number of patients. Pain from venous blood pooling due to obstruction to the venous return by a tumor is not ischemic in nature but of a heavy dull type. A typical example is headache in 280
the superior vena cava syndrome. The superior vena cava syndrome is a radiotherapeutic emergency and immediate local irradiation is justified even without histological proof of neoplasm. Results following local radiotherapy are extremely gratifying.'
Tissue Destruction Tissue destruction is one of the cardinal features of cancer, and whenever it occurs there is pain. Pain is the most frequent symptom of bone destruction either from primary or metastatic bone cancer. Relief of bone pain is of vital importance because it could cause the patient to become bedridden, leading to further complications such as decubitus ulcers and hypercalcemia. 4.ocal bone irradiation relieves pain in 70 to 80 percent of patients with metastatic bone disease.2 Radiation not only relieves pain by destroying the tumor but also helps in new bone formation and prevention of pathological fractures which could result in neurological deficit. Pain
due to bone destruction in a previously irradiated area should be properly investigated before further irradiation because this could be due to osteoradionecrosis. Osteoradionecrosis is commonly seen in the mandible of patients irradiated for head and neck cancers. Marked reduction in the amount of salivary flow from head and neck irradiation initiates the whole process of osteoradionecrosis.
Pressure Tumor growth in closed spaces like the cranium, spinal canal, and superior sulcus immediately produces pressure on adjacent nerves, resulting in severe pain and/or paralysis. Decompression is the key to relieving pain and preventing paralysis. In primary tumors of the central nervous system, except those in the brain stem region, surgical decompression is the treatment of choice. However, in pituitary adenomas and metastatic brain tumors radiotherapy plays
JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 71, NO. 3, 1979
Figure 3. Barium swallow of a patient with carcinoma of the middle third of the esophagus. There is
Figure 4. Barium swallow of the same patient shown in Figure 3 after completion of external irradiation showing normal flow of the barium through the esophagus.
almost total obstruction to the flow of barium.
a very important role.3 In brain tumors, increased intracranial pressure is due not only to the tumor but also to reactive brain edema. Therefore, brain irradiation to a patient with increased intracranial pressure should be given under steroid cover to compensate for the initial radiation edema. The mechanism of pain in superior sulcus tumors is due not only to pressure on the brachial plexus but also to destruction of the adjacent ribs. Local radiation relieves root pain by lessening pressure on the brachial plexus, relieves bone pain by destroying the tumor involving the ribs, and helps in new bone formation.4 Hepatic metastases also cause severe pain in the right upper quadrant because of the pressure on the capsule. Both primary and metastatic liver tumor are richly supplied by the hepatic artery with oxygenated blood. Therefore, because of limitation of the radiation dose that can be delivered to the liver without damaging normal liver tissue, hepatic tumors, though not cured, respond to local irradiation and pain relief is achieved in 85 percent of
patients.5 Metastatic spinal cord tumors, with partial block on myelogram, can be effectively treated with local irradiation under steroid cover. Tumors in areas other than cranium, spinal canal, and superior sulcus also can cause pain due to pressure. However, such pain is a late symptom unlike that in these closed locations.
pain by whatever means is very gratifying. Radiotherapy, along with other methods, plays an important role in achieving this. Discomfort, whatever the cause, is aberrant and requires study, empathy, and perhaps sympathy or therapy. A critical attitude, fine diagnostic acumen, and the ability to gain the confidence of the patient are paramount qualities in a good physician who manages patients suffering from pain.
Conclusions and Summary There are many mechanisms by which irradiation relieves pain in a cancer patient. However, the main mechanism is by shrinking tumor volume and relieving pressure on nerve endings or obstruction in a hollow viscus or to the blood flow. In pain due to destruction of tissue o& to infection secondary to tissue destruction by tumor, irradiation helps in relief by destroying the tumor. In most cancer patients, pain heralds advanced disease and is, of course, very distressing to the patient, relatives, and the physician. Relief of
JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 71, NO. 3, 1979
Literature Cited 1. Kumar P: Value of radiotherapy in superior vena cava syndrome. J Natl Med Assoc 70:111-112, 1978 2. Hendrickson FR, Sherata WM, Kirchner AB: Radiation therapy for osseous metastasis. Int J Radiation Oncology Biol Phys 1:275-278, 1976 3. Deutsch M, Parsons JA, Mercado R: Radiotherapy for intracranial metastases. Cancer 34:1607-1611, 1974 4. Hilaris BS, Luomanen RK: Interstitial irradiation of apical lung cancer. Radiology 99:655-660, 1971 5. Phillips R, Karnofsky DA, Hamilton LD, et al: Roentgen therapy of hepatic metastases. Am J Roentgenol Radium Therapy NucI Med 71:826-834, 1954
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To a cancer patient, pain is a very distressing symptom and to the physician it heralds advanced nature of the disease. While the mechanisms of initiation of pain are simple, its perception is very complex. In cancer, the tumor growth which results in producing pressure, destruction of tissue, and obstruction is the main cause of pain production. Ionizing radiation, which checks tumor growth and shrinks the tumor most of the time, plays a major role in relieving pain in a cancer patient. Nearly 50 percent of all cancer patients receive radiotherapy at one time or other during the course of their disease. Pain is one of the major symptoms of all cancer patients seen in the radiotherapy department. Experiencing pain is the most distressing thing in one's life, and, as Sir Thomas Lewis stated, "pain defies a definition but the word would be understood by those who read about it because of past experience." After Descartes many years ago postulated the theory that pain perception was similar to ringing a church bell by pulling on one end of the rope, the other end of which is tied to the bell, other theories have been put forward to explain the neurophysiology of pain perception. Now we know that pain perception is not as simple as explained in the specificity theory, because after various neurosurgical procedures to relieve pain, if the patient survives long enough, the pain returns. Therefore, it is of vital importance to treat the cause of the pain as effectively
Requests for reprints should be addressed to Dr. P. Pradeep Kumar, Department of Radiotherapy, Howard University Hospital, 2041 Georgia Avenue NW, Washington, DC 20060.
as possible before attempting other indirect modalities of pain relief.
Origin of Pain in Cancer Patients The mechanism of origin and perception of pain in a cancer patient can be attributed to tumor and host factors. Host factors that influence this perception are psychologic, cultural, and protective-adoptive reactions of the patient to pain. In a cancer patient, the very thought of having the disease could initiate and/or precipitate pain. For this reason it sometimes becomes necessary to withhold the diagnosis of cancer from him/her. Those involved in the management of cancer patients know well enough that the ones from lower socioeconomic groups all over the world tolerate pain much better and require milder analgesics than those from higher socioeconomic groups. Development of protective adaptive reactions to pain in a cancer patient is a very important phenomenon in perception of the pain. Psychophysical therapy plays a very important role in helping one to develop such protective-adaptive reactions.
JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 71, NO. 3, 1979
The role of radiotherapy in relieving cancer pain is associated with tumor factors causative of pain. The four major tumor factors that are important in originating pain are infection, obstruction, destruction of tissue, and pressure.
Infection Infection of a tumor usually occurs following breakdown in the continuity of surface. The dead tumor tissue forms a good medium for growth of microorganisms. Infection is a common cause of pain in tumors of the upper and lower ends of the gastrointestinal tract, genitalia, and skin. Even though ionizing radiation has a sterilization effect on micro-organisms, the radiation dose required for this purpose is usually ten times greater than the dose given to a tumor, which is also the dose tolerated by normal tissue. Therefore, radiation does not play any role by direct action on the micro-organisms in relieving pain due to tumor infection. However, infection could occur, not in the tumor directly, but proximal to it, by blocking a normal drainage pathway. The best example of pain resulting from infection secondary to obstruction to normal drainage is flank pain due to kidney infection from carcinoma of the cervix obstructing the ureters (Figure 1). In many instances, pelvic irradiation relieves the mechanical obstruction and facilitates normal drainage, which clears the proximal infection and relieves pain (Figure 2). 279
/
Figure 2. VP of the same patient shown in Figure 1 after completion of external and intracavitary pelvic irradiation. The left kidney is seen functioning normally.
Figure 1. IVP of a patient with Stage IIIB carcinoma of the cervix showing nonfunctioning left kidney.
Obstruction Occlusion of a hollow viscus by a tumor causes severe colicky pain. Obstruction to arterial or venous blood flow gives rise to ischemic or congestive pain, respectively. The visceral pain is always referred to the corresponding dermatomes. In esophageal cancer (Figure 3) obstruction to food causes referred pain in the presternal region. Even though survival rates in patients with esophageal cancer are devastating, local irradiation shrinks the tumor, opens the obstruction and relieves pain in a great number of patients (Figure 4). An example of ischemic pain due to tumor is severe abdominal pain in patients with metastatic neoplasm to celiac nodes encasing the celiac axis. Local irradiation to the celiac nodes helps to reduce the encasement and relieves ischemic pain in a considerable number of patients. Pain from venous blood pooling due to obstruction to the venous return by a tumor is not ischemic in nature but of a heavy dull type. A typical example is headache in 280
the superior vena cava syndrome. The superior vena cava syndrome is a radiotherapeutic emergency and immediate local irradiation is justified even without histological proof of neoplasm. Results following local radiotherapy are extremely gratifying.'
Tissue Destruction Tissue destruction is one of the cardinal features of cancer, and whenever it occurs there is pain. Pain is the most frequent symptom of bone destruction either from primary or metastatic bone cancer. Relief of bone pain is of vital importance because it could cause the patient to become bedridden, leading to further complications such as decubitus ulcers and hypercalcemia. 4.ocal bone irradiation relieves pain in 70 to 80 percent of patients with metastatic bone disease.2 Radiation not only relieves pain by destroying the tumor but also helps in new bone formation and prevention of pathological fractures which could result in neurological deficit. Pain
due to bone destruction in a previously irradiated area should be properly investigated before further irradiation because this could be due to osteoradionecrosis. Osteoradionecrosis is commonly seen in the mandible of patients irradiated for head and neck cancers. Marked reduction in the amount of salivary flow from head and neck irradiation initiates the whole process of osteoradionecrosis.
Pressure Tumor growth in closed spaces like the cranium, spinal canal, and superior sulcus immediately produces pressure on adjacent nerves, resulting in severe pain and/or paralysis. Decompression is the key to relieving pain and preventing paralysis. In primary tumors of the central nervous system, except those in the brain stem region, surgical decompression is the treatment of choice. However, in pituitary adenomas and metastatic brain tumors radiotherapy plays
JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 71, NO. 3, 1979
Figure 3. Barium swallow of a patient with carcinoma of the middle third of the esophagus. There is
Figure 4. Barium swallow of the same patient shown in Figure 3 after completion of external irradiation showing normal flow of the barium through the esophagus.
almost total obstruction to the flow of barium.
a very important role.3 In brain tumors, increased intracranial pressure is due not only to the tumor but also to reactive brain edema. Therefore, brain irradiation to a patient with increased intracranial pressure should be given under steroid cover to compensate for the initial radiation edema. The mechanism of pain in superior sulcus tumors is due not only to pressure on the brachial plexus but also to destruction of the adjacent ribs. Local radiation relieves root pain by lessening pressure on the brachial plexus, relieves bone pain by destroying the tumor involving the ribs, and helps in new bone formation.4 Hepatic metastases also cause severe pain in the right upper quadrant because of the pressure on the capsule. Both primary and metastatic liver tumor are richly supplied by the hepatic artery with oxygenated blood. Therefore, because of limitation of the radiation dose that can be delivered to the liver without damaging normal liver tissue, hepatic tumors, though not cured, respond to local irradiation and pain relief is achieved in 85 percent of
patients.5 Metastatic spinal cord tumors, with partial block on myelogram, can be effectively treated with local irradiation under steroid cover. Tumors in areas other than cranium, spinal canal, and superior sulcus also can cause pain due to pressure. However, such pain is a late symptom unlike that in these closed locations.
pain by whatever means is very gratifying. Radiotherapy, along with other methods, plays an important role in achieving this. Discomfort, whatever the cause, is aberrant and requires study, empathy, and perhaps sympathy or therapy. A critical attitude, fine diagnostic acumen, and the ability to gain the confidence of the patient are paramount qualities in a good physician who manages patients suffering from pain.
Conclusions and Summary There are many mechanisms by which irradiation relieves pain in a cancer patient. However, the main mechanism is by shrinking tumor volume and relieving pressure on nerve endings or obstruction in a hollow viscus or to the blood flow. In pain due to destruction of tissue o& to infection secondary to tissue destruction by tumor, irradiation helps in relief by destroying the tumor. In most cancer patients, pain heralds advanced disease and is, of course, very distressing to the patient, relatives, and the physician. Relief of
JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 71, NO. 3, 1979
Literature Cited 1. Kumar P: Value of radiotherapy in superior vena cava syndrome. J Natl Med Assoc 70:111-112, 1978 2. Hendrickson FR, Sherata WM, Kirchner AB: Radiation therapy for osseous metastasis. Int J Radiation Oncology Biol Phys 1:275-278, 1976 3. Deutsch M, Parsons JA, Mercado R: Radiotherapy for intracranial metastases. Cancer 34:1607-1611, 1974 4. Hilaris BS, Luomanen RK: Interstitial irradiation of apical lung cancer. Radiology 99:655-660, 1971 5. Phillips R, Karnofsky DA, Hamilton LD, et al: Roentgen therapy of hepatic metastases. Am J Roentgenol Radium Therapy NucI Med 71:826-834, 1954
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