Medical advancement has transitioned cancer from being a rapidly fatal disease to a chronic disease. Cancer pain, however, still remains a major problem affecting 30–40% at the time of diagnosis, and 75% of those with advanced cancer. Although it may not always be possible to relieve the cancer-related pain completely but fortunately it can be effectively managed in most individuals with appropriate therapy. Effective pain control has been shown to improve the quality of life in all stages of the disease. Breakthrough pain is one pain which troubles even those cancer patients whose pain is otherwise well controlled. Its management requires careful evaluation by specialists with attention to detail. In the subsequent section we discuss more about the breakthrough pain and commonly asked questions.

What is breakthrough pain?

Breakthrough cancer pain (BTcP) is a transient exacerbation of pain superimposed on the background of controlled persistent pain. In simple words it refers to the sudden, relatively short lasting severe pain episodes one experiences from time to time, often catching one unprepared, despite having background pain well controlled.

Here are a few characteristics of breakthrough pain

• Pain is of moderate to severe intensity (between 4-10/10, average score 7/10)
• Onset is rapid (between 3 to 5 minutes) or in some cases more gradual reaching peak intensity within a few minutes. In about two thirds of the patients time to maximum pain intensity is less than 10 minutes
• Duration of an untreated episode can be between 1 min and 4 h (average 30 min)
• Multiple, predictable (in one third of patients) or unpredictable episodes throughout the day

Effective pain management requires assessment of responsible factors and having a management plan rather than trying to reach out for emergency services during unsocial hours in a panic mode. 

How common is breakthrough pain and what causes this pain?

BTcP is a common problem with studies reporting the incidence as approx. 50% to 75%. This is despite using strong painkillers to control the baseline pain. Patients with the severe persisting pain, advanced cancer disease, and aggressive anticancer treatments are more likely to experience breakthrough pain. 

BTcP may result from the cancer itself (70–80% of cases) or the anticancer treatment (10–20% of cases) and is seen more commonly is association with certain cancers like head and neck cancer (70%), gastrointestinal (59%), lung (55%) and breast cancer (52%). Common examples of BTcP include mouth pain on swallowing due to inflammation of mouth lining (mucositis) or bone pain due to movement. 

BTcP can originate from numerous sources (somatic, visceral, or neuropathic) and the cause may be different from the sources of persisting background pain. It may be associated with 

• Voluntary movements like sitting, standing
• Involuntary movements like intestinal distension or
• May occur spontaneously

This distinction is relevant as it may encourage more targeted treatment approaches. Up to half of the patients may experience two or more types of BTcP. Sometimes the term episodic pain is used synonymously with breakthrough pain although some researchers ascribe a different meaning to this term.

Another type of BTcP which one commonly encounters is the increased pain that can occur when the effect of painkillers is wearing off, just before the next dose is due. This is addressed as the “end of dose failure.” Some studies include this as a type of breakthrough pain whereas others do not.

Why do we need to treat breakthrough pain?

Breakthrough cancer pain is a common problem and can be associated with a variety of physical, psychological and social complications. Persisting pain often robs the sufferers of their independence and their ability to perform routine tasks, adversely affecting the quality of life. Besides causing suffering, the severity and unpredictability of breakthrough pain can adversely impact one’s confidence level, emotional health and social interactions. Moreover, it is associated with increased utilisation of healthcare and social care services with obvious financial implications.

How do we address this type of pain?

All cancer pain patients should be specifically assessed for the presence of BTcP. A standard pain management & palliative care practice is to prescribe medications for the constant background pain and a separate on-demand dose of pain relieving measures for breakthrough pain. In BTcP there is no one treatment which works universally and the treatment needs to be individualised. 

Selecting the right option requires a fair amount of expertise and familiarity with all the available options. There are a number of factors which need to be taken in to account when deciding on the treatment and these include

• Underlying cause of pain
• Type of pain (nerve pain, nociceptive, mixed)
• Pain characteristics (onset, duration, severity)
• Predictable or unpredictable
• Previous response to pain relieving medications including opioids (efficacy, tolerability)
• Background analgesic medications (may need to be adjusted) and drug interactions
• Patient-related factors including age, other organ function, stage of the cancer and individual preferences
• Cost, availability and safety aspects

Opioids (morphine like drugs) are considered as the preferred medications for treating BTcP. The profile of the drug selected to treat the BTcP needs to mirror the pain profile one is experiencing. For example, in cases of sudden onset short-lasting pain episodes, drugs like oral morphine may prove to be ineffective as they take 30 to 45 minutes to work. In such a situation rapidly acting drugs are more likely to be useful. A mismatch between pain profile and drug selected is likely to produce poor relief and/or more side effects 

The route of drug administration is important as it controls how quickly the pain relieving effects are apparent. Drugs given directly into the veins have a rapid effect although it requires an intravenous cannula to be present. Alternative routes such as through the nose or by intraoral route (sucking on tablets) of the rightly chosen drugs work within 5 -15 min. The dose of ‘rescue medication’ is determined by individual titration to ensure maximum relief with minimal side effects and may be subject to change over time.

A predictable episode of BTcP triggered by known factors for example, eating can be managed by a planned administration of medicine prior to the activity taking into account the time taken for the medication to work. Some patients choose to restrict activity to reduce the number of  BTcP episodes.

Once the trial medication has been started, dose titration and regular reassessments are essential. All patients with new BTcP medications should be reevaluated within 48–72 h. Patient education regarding the correct and appropriate use of medications is essential as research evidence demonstrates incorrect usage, misuse / abuse and underuse in a significant proportion. 

Other non-opioid drugs are also useful in the management of BTcP. Examples include anti-inflammatories, benzodiazepines, paracetamol etc. Preventing and treating BTcP is not just about medications as interventional techniques and non-pharmacological methods are other options which can be helpful.

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