Understanding the Causes of Cancer Pain: Unveiling the Mystery Behind the Discomfort

I. Introduction

A. How Common is Cancer Pain? 

Cancer pain affects 24-73% of patients undergoing active treatment, 58-69% in those with advanced cancer or terminal disease, and 21-46% in those in remission. Despite effective treatment options an estimated 32-43% of cancer pain remains undertreated resulting in decreased quality of life for many patients. 

A. Tumor Growth, Invasion, and Metastasis

Tumor growth and invasion play a significant role in the development of cancer pain. As cancer cells proliferate, tumors can exert pressure on surrounding tissues, organs, and nerves, leading to pain. The pressure exerted by the tumor can cause localized pain at the site of the tumor itself. Additionally, tumors can also generate referred pain, where the pain is felt in areas distant from the tumor due to nerve connections and pathways.

Metastasis is a critical stage in cancer progression where cancer cells spread from the primary tumor to other parts of the body. It is a complex process involving the invasion, migration, and establishment of cancer cells in distant organs or tissues. Metastatic cancer can cause pain due to its impact on surrounding structures and the disruption of normal bodily functions.

As cancer cells break away from the primary tumor, they can enter the bloodstream or lymphatic system, allowing them to travel to distant sites in the body. Once they reach these new locations, they can form secondary tumors and exert pressure on nearby tissues, nerves, or organs. The presence of these secondary tumors can lead to localized pain, depending on the affected area.

B. Cancer Treatments

Cancer treatments, such as chemotherapy, radiation therapy, and surgeries, can contribute to the development of cancer pain. These treatments, while essential for combating cancer, can have unintended effects on the body, including pain-related symptoms.


Chemotherapy, a systemic treatment aimed at killing cancer cells, can lead to various side effects that contribute to pain by harming your body’s normal cells. These side effects may include peripheral neuropathy, which is characterized by nerve damage and pain in the hands and feet. Additionally, chemotherapy-induced mucositis, inflammation of the mucous membranes, can cause oral and gastrointestinal pain.


Radiation therapy, targeted at specific areas affected by cancer, can cause tissue inflammation and damage. This can result in localized pain at the radiation site, especially in the weeks following treatment. Radiation-induced fibrosis, the formation of scar tissue, can also contribute to pain and stiffness in the treated area.


Surgeries performed to remove tumors or affected tissues can lead to postoperative pain. Incisions, tissue trauma, and nerve irritation are common causes of surgical pain. Depending on the complexity and extent of the surgery, pain levels can vary.

III. Conclusion

  1. Find a provider who is trained in cancer pain management. Look at where your doctor was trained (e.g., Moffitt, MD Anderson, Memorial Sloan Kettering, Harvard, etc.). Not all pain management training programs train doctors on how to perform cancer pain injections and surgeries, manage high doses of opioids, or understand how your cancer and cancer treatments affect your pain management options. 
  2. Find a clinic that provides on-call services, will visit patients in the hospital, and can help you with your acute pain management needs 24/7. Cancer pain management often requires more frequent visits than chronic pain, and it is important that your doctor can get you in on the same day, the next day, or via telehealth if you are having a crisis. 
  3. Find a clinic that focuses on more than medications, injections, and surgeries and incorporates holistic options such as medical marijuana, herbal medications, mind-body exercises, nutritional support, and symptom management (e.g., nausea, constipation, etc.). 
  4. Finally, ask your doctor if they coordinate with your oncologists directly and have easy access to your records. Since cancer and cancer treatments evolve quickly is important that your pain doctor coordinates with your oncologists frequently. 

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