Cancer Pain

Cancer pain is pain that arises in people with cancer, whether caused directly by the tumour, by its spread, or by cancer treatment. It is one of the most feared consequences of malignant disease and is common across the course of illness, especially in advanced and metastatic cancer.

Definition

Cancer pain is pain caused by cancer itself (for example by tumour invasion of bone, nerve, or viscera), by its metastases, or by cancer-directed treatment such as surgery, chemotherapy, or radiotherapy; it may have nociceptive, neuropathic, or mixed features.

Scope

This topic covers what cancer pain is, the mechanisms by which tumours and their treatment produce pain, the place of cancer pain within palliative and supportive care, and the public-health concern of unrelieved cancer pain and access to analgesia. It is a reference overview and does not provide dosing or individualised treatment advice.

Key concepts

• Tumour-related vs treatment-related pain
• Nociceptive and neuropathic components
• Bone metastasis pain
• Chemotherapy-induced peripheral neuropathy
• Breakthrough cancer pain
• Barriers to access to analgesia

Mechanisms

Cancer pain is mechanistically heterogeneous. Tumour growth can stimulate and sensitise nociceptors directly and through inflammatory and acidic mediators in the tumour microenvironment; invasion or compression of bone, nerves, and viscera produces nociceptive and neuropathic pain. Bone metastases, a common source of cancer pain, involve osteoclast-driven bone destruction and sensitisation of sensory nerves. Cancer treatments add further mechanisms, such as chemotherapy-induced peripheral neuropathy. Many patients experience breakthrough pain — transient flares superimposed on otherwise controlled background pain.

Clinical relevance

Cancer pain is a central concern of oncology and palliative care because it is common, often treatable, and a major determinant of quality of life. This entry describes the syndrome and its mechanisms as reference material; it summarises that structured, guideline-based assessment is used clinically and does not provide individualised treatment or dosing recommendations.

Epidemiology

Pain is reported by a large proportion of patients with cancer, with prevalence rising in advanced and metastatic disease. Worldwide analyses also highlight that access to opioid analgesics for moderate-to-severe cancer pain is markedly inadequate in much of the world, a recognised global health inequity.

History

The modern approach to cancer pain was shaped by the hospice and palliative-care movement and by the World Health Organization, whose 1986 framework for cancer pain relief introduced a stepwise approach to analgesia that became widely influential. Subsequent classification work incorporated chronic cancer-related pain into the ICD-11 chronic pain framework, and contemporary clinical practice guidelines have refined assessment and management.

Debates

Why does cancer pain remain undertreated globally?

Despite available treatments, unrelieved cancer pain persists worldwide, driven in large part by restricted access to opioid analgesics arising from regulatory, economic, and educational barriers rather than lack of effective options.

Key figures

• Marie Fallon
• Carla Ripamonti

Seminal works

• fallon-2018
• berterame-2016

Frequently asked questions

Is all cancer pain caused by the tumour itself?

No. Cancer pain may be caused directly by the tumour or its spread, but it can also result from cancer treatments such as surgery, chemotherapy, or radiotherapy, and a single patient may have more than one source of pain.

What is breakthrough cancer pain?

Breakthrough cancer pain is a transient flare of pain that occurs against a background of otherwise controlled pain, either spontaneously or triggered by activity.