What is Malignant Cancer?
Malignant cancer is growing tumor, which progressively gets worse and has a tendency to metastasis (infiltrate or spreads to adjacent and distant organs).
What Is Malignant Cancer Pain?
Malignant cancer pain is either acute pain or chronic pain. Acute pain lasts for 3 to 6 months and chronic pain lasts for more than 6 months. Malignant cancer pain is either nociceptive or neuropathic pain.
What Are The Different Types Of Malignant Cancer Pain?
Malignant cancer pain is classified as somatic or visceral chronic pain. Somatic means relating to the body, especially as distinct from the mind. Visceral means the internal organs of the body, especially organs within the chest or abdomen.
What is Somatic Pain?
Somatic pain is mostly localized over skin, muscles, tendons or bones.
Somatic pain is described as
- Initial Phase:
- Nociceptive Somatic Pain.
- Sharp, Shooting or Stabbing Pain.
- Well localized.
- Later Phase:
- Neuropathic or Mixed Pain.
- Burning Pain Associated With Allodynia and Hyperalgesia.
What are the Examples of Somatic Pain?
Example of malignant cancers causing somatic pain is as follows.
Skin Cancer- Melanoma
Muscle Cancer- Rhabdomyosarcoma
Fibrous Tissue or Tendon Cancer- Sarcoma
Bone cancer- Osteosarcoma
What is Visceral Pain?
Visceral pain is described as
- Initial phase:
- Nociceptive visceral pain.
- Diffused pain, squeezing and dull pain.
- Not well localized like somatic pain.
- Later phase:
- Neuropathic pain.
- Character of pain: Allodynia or hyperalgesia to touch or pressure.
- Associated with symptoms like nausea, vomiting; blood in urine, sputum and stool.
What are the Examples of Visceral Pain?
Visceral pain is localized around cancer tumor mass of organs, glands or soft tissue. Visceral pain is observed in neck, chest, abdomen or pelvis.
Examples of visceral malignant cancer tumor resulting in visceral pain are as follows:
Headache and Facial Pain Caused by Cancer of Brain- Malignant Glioma, Metastatic Brain Tumor.
Neck Pain Caused by Cancer of Thyroid Gland-Thyroid Cancer.
Neck and Throat pain Caused by Cancer of Pharynx and Larynx- Pharyngeal and Laryngeal Carcinoma.
Neck and Chest Pain Caused by Cancer of Esophagus- Esophageal Carcinoma.
Chest Pain Caused by Cancer of Breast- Ductal and Lobular Carcinoma.
Chest and Mid Back Pain Caused by Cancer of Trachea- Squamous Cell and Adenoid Cystic Carcinoma.
Chest Pain Caused by Lungs- Lung Carcinoma.
Abdominal Pain Caused by Cancer of Intestine- Adenocarcinoma.
Abdominal and Lower Back Pain Caused by Cancer of Pancreas- Pancreatic Carcinoma.
Pelvic and Lower Abdominal Pain Caused by Cancer of Uterus- Endometrial Carcinoma.
Pelvic, Groin and Vaginal Pain Caused by Cancer of Vagina- Vaginal Carcinoma.
Lower Back and Flank Pain Caused by Kidney- Renal Cell Carcinoma, Urothelial Cell Carcinoma and Renal Pelvis Carcinoma.
Lower Abdomen and Pelvic Pain Caused by Urinary Bladder- Transitional Cell Carcinoma and Sarcoma.
Pain During Urination and Perineal Pain Caused by Cancer of Urethra- Transitional Cell Carcinoma.
Thyroid Gland-Thyroid Cancer
Pharynx and Larynx- Pharyngeal and Laryngeal Carcinoma
Esophagus- Esophageal Carcinoma
Breast- Ductal and Lobular Carcinoma
Trachea- Squamous Cell and Adenoid Cystic Carcinoma
Lungs- Lung Carcinoma
Pancreas- Pancreatic Cancer
Uterus- Endometrial Carcinoma
Kidney- Renal Cell Carcinoma, Urothelial Cell Carcinoma and Renal Pelvis Carcinoma
Urinary Bladder- Transitional Cell Carcinoma and Sarcoma
Urethra- Transitional Cell Carcinoma
What Is Nociceptive Somatic Pain?
Nociceptive pain is burning, shooting and stabbing type of pain caused by irritation of pain receptors and nerve fibers by chemicals secreted by inflamed or necrotic tissues. Pain is very well localized in skin and skeletal tissue. Pain receptors located in skin; muscles, tendons and bones are known as nociceptors. Nociceptive pain responds to anti-inflammatory medication.
What Is Neuropathic Somatic Pain?
Nociceptive (pain) receptors and pain carrying sensory fibers become hypersensitive following continuous irritation. Simple touch or pressure of hypersensitive receptors results in intense pain. Neuropathic pain is associated with allodynia (mild pain is felt as severe pain), hyperalgesia (simple touch is felt as severe pain) and hyperpathia (severe widespread pain). Neuropathic pain becomes continuous burning pain following central sensitization.
What Is Central Sensitization?
Inadequately treated neuropathic pain often causes hypersensitivity of central pain receptors and sensory pain transmitting nerves, which are located within the spinal cord and pain centers. Hyperactivity of receptors and nerves in spinal cord and pain center is known as central sensitization. Central sensitization results in uninterrupted neuropathic pain at rest and with activities.
What Is Mix Pain?
Mix pain has both nociceptive and neuropathic character of the pain. Somatic pain caused by malignant tumor may present as nociceptive pain, neuropathic pain or mix pain. Pain is often severe and intractable.
What Is Visceral Neuropathic Pain?
Visceral neuropathic pain is caused by central sensitization and irritation of pain receptors and nerve fibers by tumor cells following infiltration and rapid growths.
What Causes Severe Intractable Pain in Malignant Cancer?
Malignant cancer tumor results in severe intractable pain secondary to following causes:
- Rapid growth of tumor.
- Infiltration of tumor cells.
- Ischemic changes.
- Tissue necrosis.
- Tissue damage following radiation treatment.
- Pain caused by neuropathy secondary to chemotherapy.
- Pain following surgery.
- Tumor cell infiltration in nerve plexus.
Why Rapid Growth Of Tumor Causes Severe Pain?
Malignant cancer grows faster than benign cancer. Swift growth causes excessive pressure on adjacent organ and peripheral nerves. Disproportionate compression of the receptors and nerve fibers results in pain.
Why Tumor Infiltration Results In Severe Pain?
Primary or metastatic malignant cancer infiltrate into adjacent organs and soft tissue. Tumor cells infiltrate into peripheral nerves and organ resulting in severe intractable pain. Infiltration in adjacent organ also causes pressure symptoms or expansion of the surface of the organ resulting visceral peritoneal irritation.
How Does Ischemic Changes Cause Severe Pain?
Malignant cancer tumor infiltrates into blood vessel or obliterates the lumen of the blood vessel following rapid expansion. Tumor infiltration in to blood vessels or obliteration of blood vessels causes lack of forward blood flow. Lack of blood supply to organ follows tissue necrosis resulting in lack of oxygen and nutrient supply to organ. Tissue metabolizes in hypoxic or low oxygen level results in accumulation of acids and toxins, which causes severe intractable pain.
Why Radiation Therapy Results In Chronic Pain?
Radiation treatment causes severe scar tissue and shrinkage of the tissue mass. Scarring of soft tissue surrounding malignant cancer tissue often causes pinch or entrap nerves in thick fibrous tissue resulting in severe intractable neuropathic pain. Scarring is often associated with tumor and adjacent tissue necrosis and atrophy. Initial nociceptive pain is caused by tissue inflammation. Later pain becomes neuropathic secondary to scarring of sensory nerves and nerve plexus, which are located in the soft tissue between organs.
Causes of Pain after Radiation Treatment Are As Follows
- Tissue necrosis.
- Tissue atrophy.
- Scarring pinching sensory nerve and nerve plexus.
Why Does Chemotherapy Cause Pain?
Complication such as sensory neuropathy following chemotherapy often causes severe neuropathic pain.
Does The Pain Following Surgery Become Chronic?
Yes and no, surgery pain is nociceptive pain and pain disappears once wound is healed. Cancer patients often are malnourished and wound healing is delayed. Wound often gets infected. Prolonged wound healing and infected wound in malnourished patient may result in neuropathic pain.
Is Nerve Plexus Infiltration Painful?
Malignant tumor either primary or secondary (metastatic tumor) when situated close to nerve plexus, peripheral nerve or spinal cord may encroach upon the nerve or spinal cord causing severe pain. Metastatic tumor of vertebral column can infiltrate in to spinal cord causing severe pain or severe nerve damage resulting in paralysis.
Does Chronic Pain Interfere With Quality Of Life In Cancer Patient?
Yes, cancer pain is the most unbearable pain one can imagine. Cancer pain interferes with quality of life of the patient and close relatives.
How Difficult Is The Treatment To Reduce The Pain To Improve Quality Of Life Of Cancer Patient?
Treatment is challenging to oncologist and pain specialist. Recent advances in Pain Management have indicated pain can be reduced up to 75% or more.