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It may be seen as a statement of the obvious that cancer causes pain. However, the pain associated with cancer is a complex experience that typically stems from the physical presence of the tumour itself or the biological changes it forces upon the body. The most direct cause of discomfort occurs when a growing tumour takes up space and puts physical pressure on surrounding tissues. As a tumour expands, it can press against nearby nerves, stretch the sensitive membranes covering internal organs, or squeeze blood vessels, which restricts blood flow and deprives tissues of vital oxygen. If a cancer spreads into the skeletal system, it can disrupt the natural structure of the bone, stretching the pain-sensitive outer layer of the bone or causing tiny structural fractures that lead to severe, localized discomfort. Beyond the physical pressure of a tumour mass, cancer causes pain through chemical irritation and widespread inflammation. Tumour cells and the body’s own immune response release a variety of chemical signals and inflammatory substances into the surrounding tissue. These chemicals actively irritate nearby nerve endings, lowering their pain threshold and making them hyper-sensitive to even minor movements. Furthermore, if a tumour blocks a hollow organ or duct—such as an airway, a bile duct, or the intestinal tract—it can cause a painful buildup of pressure, forcing the surrounding muscles to spasm intensely as they try to push past the obstruction. Whether through direct mechanical pressure or chemical irritation, these combined forces signal the brain that tissue damage is occurring. Read a transcript
According to the European Society for Medical Oncology (ESMO) clinical guidelines, managing cancer pain effectively begins with understanding that while pain is highly prevalent—especially in the advanced stages of the disease—it is a thoroughly treatable condition that should never simply be accepted.
Pain can stem from direct tissue damage, such as bone or organ pain, or from nerve injuries that cause burning, tingling, or shooting sensations. Furthermore, pain can arise from the cancer itself or as a temporary side effect of essential treatments like surgery, chemotherapy, or radiation. Because undertreatment remains a widespread issue globally, patients and their families are strongly encouraged to take an active role in their care.
Patients with cancer should speak up early and clearly describe how the pain impacts your daily life, sleep, appetite, and mood. Medical teams routinely monitor this by asking patients to rate their worst pain over the last 24 hours on a scale from 0 to 10. They will pay particularly close attention to any pain rated at a 3 or higher, or any pain causing significant emotional distress.
When treating persistent chronic pain, healthcare professionals follow a stepped medication approach. They prioritize the oral route whenever swallowing is possible, as pills are the easiest way for families to manage care at home. Rather than waiting for pain to return and taking medication only “as needed,” analgesics are prescribed on a strict, around-the-clock schedule to prevent pain spikes from occurring in the first place.
Mild pain is typically treated with non-opioids like paracetamol or anti-inflammatory drugs (NSAIDs). As pain progresses to a mild-to-moderate level, weak opioids or low doses of strong opioids are introduced. For moderate-to-severe pain, strong oral opioids are the standard first choice, with morphine being the most widely used.
Even when background pain is stabilized, patients may still experience sudden, intense flares known as breakthrough cancer pain. To manage these sudden spikes, doctors proactively prescribe immediate-release “rescue” medications.
While standard oral opioids can help with slow-onset flares, unpredictable and rapid-onset breakthrough pain is best treated with rapid-onset transmucosal fentanyl formulations. These dissolving tablets or nasal sprays are absorbed quickly through the lining of the mouth or nose, providing noticeable relief within 10 to 15 minutes.
Because opioid therapies routinely trigger side effects, managing them is a critical part of the overall care plan. Opioid-induced constipation is nearly universal and does not improve over time, meaning laxatives must be routinely prescribed as a preventative measure from day one. Nausea and vomiting are also common when first starting these medications but can be successfully controlled with anti-sickness drugs.
More severe central nervous system side effects—such as extreme drowsiness, confusion, or a paradoxical worsening of pain known as opioid-induced hyperalgesia—require immediate medical attention. In these cases, doctors may need to adjust the dosage, improve patient hydration, or switch to an alternative opioid altogether.
For complex or localised pain that does not respond adequately to standard medications alone, targeted treatments and advanced medical procedures offer highly effective relief. Localised bone pain caused by cancer that has spread is incredibly responsive to radiation therapy. A quick, single dose of external beam radiation is the preferred schedule to optimise patient comfort and limit hospital visits.
Specialised bone-targeted drugs, like bisphosphonates or denosumab, are also used to delay the onset of bone pain. However, patients must undergo a preventative dental checkup before starting these drugs to prevent rare jaw complications. When nerve pain is present, doctors often add specific first-line target drugs, such as tricyclic antidepressants or anti-seizure medications (like gabapentin or pregabalin), to the patient’s routine regimen.
Finally, for the small percentage of patients whose pain remains entirely resistant to conventional therapies, specialised pain teams may use more invasive techniques. These include nerve blocks to numb specific pain pathways or spinal catheters and implantable pumps that deliver medication directly to the nervous system. This direct delivery maximises pain control while drastically reducing systemic side effects.
This information is based upon:
M. Fallon, R. Giusti, F. Aielli, P. Hoskin, R. Rolke, M. Sharma & C. I. Ripamonti, on behalf of the ESMO Guidelines Committee Management of Cancer Pain in Adult Patients: ESMO Clinical Practice Guidelines, Ann Oncol. (2018) 29 (Suppl 4): iv166–iv191
