Sarcoma by Robert M. Henshaw

Author:Robert M. Henshaw
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

14.2 Causes of Cancer Pain

Pain can be the result of the cancer itself, the treatment given to manage the cancer, or completely unrelated to the cancer. Up to 75% of chronic cancer pain is the direct result of the malignancy [18]. The tumor itself produces mediators of inflammation that propagate pain. The tumor may invade surrounding structures, including nerves, bones, soft tissue, ligaments, and fascia [4]. Metastasis of the tumor to the bones may result in pain. Only one-third of advanced cancer patients have pain from one source [19–21].

Approximately 17% of patients’ pain is the result of treatment [19]. Surgical, chemotherapy, or radiation treatment of the tumor may result in painful conditions. Incisional pain may produce scar neuromas, with ectopic foci of pain. Some chemotherapeutic agents, such as cisplatin, taxanes, and vincristines, may lead to painful peripheral neuropathies [4, 22]. Radiation treatment may also inflict injury to peripheral nerves, which may occur months to years after treatment [10]. Plexopathies from radiation are more likely when the dose of radiation is greater than 60 Gy or 6000 rad cumulatively [22]. Also, there are cases of radiation-induced osteonecrosis (G4).

The types of pain are characterized as nociceptive, neuropathic, or mixed nociceptive-neuropathic. Identification of the type of pain is necessary since some agents that effectively control nociceptive pain, such as opioid analgesics, may have minimal effect on the treatment of neuropathic pain. Nociceptive pain is associated with tissue injury from surgery, trauma, inflammation, or tumor. This injury activates pain receptors in the cutaneous or deep musculoskeletal structures [4]. Nociceptive pain may be further divided into somatic and visceral pain. Somatic pain arises from injury to bones, tissues, or tendons and is mainly described as achy, dull, or stabbing. It is typically localized, and examples include tumor invading a bone, a pathological fracture, or postoperative incisional pain [4]. Visceral pain may occur from tumor stretching, invading, compressing, obstructing, or distending visceral structures. This type of pain usually presents as a poorly localized pain. Frequent descriptions of visceral nociceptive pain are deep, cramping, colicky, and squeezing, especially when an obstruction is present, and sharp and throbbing when an organ capsule is distended [23]. The pain may be referred to the shoulder if the diaphragm is irritated or to the patient’s back [4].

Neuropathic pain results from abnormal somatosensory processing in the peripheral or central nervous system [10]. Neuropathic pain may be described as pins and needles, burning, numbness, lancinating, and electrical shock-like [4]. Examples of neuropathic pain include tumor invasion or compression of plexuses, nerves, or the spinal cord, peripheral neuropathies from chemotherapeutic agents, or radiation-induced nerve injury. Even a surgical scar may develop ectopic painful nerve processing postoperatively. Why some patients develop neuropathic pain and others do not is unknown [10].

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