Why Does Cancer Cause Pain?
Sources of pain in cancer may not be easy to identify and often require detailed assessment with attention to detail. Identification of the source often holds the key to correct treatment and ability to provide relief. Pain in cancer may originate from
- Cancer itself – When cancer grows it damages the tissues. It causes inflammation, unusual stretching, irritation and all this can lead to pain. Like if we talk about a pancreatic cancer, when it grows or stretches it can irritate the diaphragm (main breathing muscle) and that cause shoulder pain
- Cancer spread – when cancer grows uncontrollably then it can spread to the nearby or distant body parts like the bone, liver, kidney, lymph nodes etc.
- Associated problems like bloating, constipation, blockage of ducts, clotting problems, distention of liver or abdomen etc.
- Cancer treatments like radiotherapy or chemotherapy are known to cause nerve pain (peripheral neuropathy. Surgery may also be associated with chronic persistent pain.
- Extra stress on other body parts – Often to protect one part of our body, we put pressure on other parts for example using crutches to offload a leg may become the source of shoulder pain as the crutches place extra load on my shoulder
- Other coincidental problems – it is not necessary that all pain that every cancer patient suffers is due to cancer. There could be other coincidental problems like in the general population such as arthritis. So it is important to identify not only the type of pain but also the source of pain, before we plan treatment.
Pain related to cancer may have different components such as background pain and breakthrough pain. These need to be taken into account while making treatment plans. Let’s take an example of pain due to pancreatic cancer. These patients may have a constant pain (background pain) and there may be increased pain that comes after eating (breakthrough pain). Breakthrough pain may happen due to provoked or unprovoked factors and when we make a treatment plan it is important to have a plan for breakthrough pain.
