Articles

CANCER PAIN: CAUSES-PAIN DUE TO TUMOUR INVOLVEMENT
The causes of pain in patients with cancer, and the relative frequencies, are:

• due to tumour involvement (70%)
• associated with treatment (20%)
• due to general illness but not cancer (<10%)
• unrelated to cancer or its treatment (<10%)

Pain due to tumour involvement-Bone metastases are the most frequent cause of pain directly attributable to cancer. Bone metastases cause pain by local bone destruction, causation of pathological fractures, infiltration of surrounding tissues, secondary muscle spasm, or by compression of neurological structures including the spinal cord and peripheral nerves.
Compression and infiltration of a peripheral nerve causes a dull ache or a constant superficial burning pain in the area of sensory loss. Infiltration of the brachial or lumbosacral plexus will produce pain and diminished sensation in the distribution of the relevant nerve roots as well as motor signs.
Soft tissue infiltration causes pain because of local tissue destruction and by infiltration of pain-sensitive tissues such as fasciae or periosteum. Soft tissue infiltration also causes pain by compression or infiltration of nerves and vessels. Infiltration of the skin and mucous membranes causes local pain sometimes aggravated by secondary infection.
Infiltration of viscera causes poorly localised deep seated .pain, often accompanied by referred pain. Involvement of the tissue capsule produces more severe sharp pain which is well localised and associated with local tenderness. Infiltration of hollow viscera will cause colic and pain which is poorly localised, often associated with referred pain.
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