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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Another subgroup of patients undergoing mastectomy are those who want to reduce their risk of developing breast cancer such as those with gene mutations (e.g., BRCA1, BRCA2) and a strong family history. Advances in surgical treatment like breast-conserving approaches have enabled patients to realistically consider this option.

Who are at risk of developing persisting pain ?

Some factors associated with increased risk of persisting pain include:

Type of surgery: Nerve preservation approaches are associated with reduced incidence of sensory deficits (53 % vs. 84 %) but may not be possible in all cases.

Different breast cancer surgery options include

• Radical mastectomy – involves removing the breast, skin, fat, chest muscles (pectoralis major and minor), and all the lymph nodes of the affected side.
• Modified radical mastectomy spares the chest (pectoral) muscles when compared to the surgery mentioned previously.
• Lumpectomy with axillary node dissection involves removal of the tumour with surrounding margin of normal tissue and the axillary (armpit) lymph nodes.
• Breast-conserving surgery (lumpectomy) also known as breast preservation, conservative breast surgery, wide local excision, partial mastectomy is generally used in early breast cancer  and involves removal of the tumour and a margin of normal tissue.
• Lumpectomy with sentinel lymph node biopsy involves removal and examination of the first axillary node (sentinel node) receiving drainage from the breast. The node is identified by injection of a special dye/ radiolabeled substance prior to the operation. If this node is free of disease, axillary dissection is not required.

Axillary nodes dissection leads to increased chances of lymphedema (arm swelling due to inadequate drainage) and poses risks to one of the nerves (intercostobrachial nerve) which is responsible for the sensation of the inner aspect of the upper arm. Both of these factors can become a source of persisting pain. The wide variation in the size, location, and branching patterns of the nerve make it more vulnerable to injury. Damage may occur as a result of stretching during surgery or direct nerve injury, presenting with numbness and pain in the area supplied by the nerve. As per one study women with axillary node dissection are 3.1 times more likely to experience moderate-to-severe pain at rest.

Other nerves in the area are also at risk of injury and can become a source of persisting pain. These include 

• Medial cutaneous nerve of the arm (provides sensation to the lower medial skin of the upper arm (damaged during section of the tributaries of the axillary vein)
• Medial and lateral pectoral nerves (control the chest wall or pectoral muscles)
• Long thoracic nerve (controls the serratus anterior muscle present along the side of chest wall close to armpit)
• Thoracodorsal nerve (controls the latissimus dorsi muscle)

Other treatments like radiation therapy administered in conjunction with surgery increase risk of persisting pain. This may be due to increased tissue fibrosis, neural entrapment, and impaired shoulder movement. Moreover, radiotherapy also increases risk for lymphedema which is another reason for persisting pain. Later-stage disease also is likely to require more aggressive treatment (i.e., chemotherapy) and may be associated with higher rates of pain. Regardless these are necessary treatments and when indicated should be pursued. 

Pre-existing pain prior to surgery is one of the most consistent factors related to increased risk of persisting pain after surgery. Even those patients with unrelated pain conditions such as headaches or low back pain are more likely to develop chronic pain after surgery. 

Severe pain after the operation requiring high doses of painkillers increases the likelihood of persisting pain.

Age: In several studies, younger age was seen to be associated with greater likelihood of persistent pain. Although the exact reason is not known, some postulated factors include presence of more aggressive cancers requiring more aggressive treatment, higher preoperative anxiety, and the need for adjuvant chemotherapy in this group.

Psychosocial distress can be both a risk factor for and a consequence of chronic pain. Preoperative anxiety has been found to be related with immediate postoperative pain levels. Numerous studies have found correlations between persisting pain after surgery and depression, stress, and psychological vulnerability. 

What are the symptoms of postmastectomy pain syndrome?

Postmastectomy pain syndrome may cause persistent or intermittent burning, shooting, stabbing, pulling, tightness, heaviness sensation or aching pain in

• Chest
• Axilla (armpit)
• Arm
• Shoulder

Other symptoms in addition to pain may include

• Numbness
• Tingling or prickling pain 
• Increased sensitivity in the area
• Spasms
• Severe itching 
• Phantom breast sensation & pain

What are the causes and different types of pains found after breast surgery?

Pain may persist after surgery due to numerous reasons such as surgical injury- nerve or muscle damage, nerve entrapment, lymphedema, mechanical causes, radiotherapy and chemotherapy, post-surgical scarring, recurrence of tumour, etc. Nerve injury pain has been further divided into the following types

Phantom Breast Pain

Phantom pain is seen after amputations where the absent body part (phantom) hurts. The patient may experience sensation as if the removed breast is still present and is painful. Often patients are confused and reluctant in sharing this with others as they feel unsure if this is actually real and possible, but phantom pain is real and not just in one’s head. Controlling this can be challenging and requires a multi-modality (using many treatment options in combination) approach.

Nerve Injury & Neuroma pain

Nerve injuries can lead to the formation of neuromas which in simple language can be explained as swelling at the end of the injured nerve. These neuromas can generate spontaneous or provoked tingling, electric shock like sensation with increased sensitivity in the area. Neuroma pain may be more common following lumpectomy than mastectomy. I have come across a few cases where the patient experienced pain as if she was having a heart attack requiring multiple visits to hospital emergency whilst the actual problem was injured pectoral nerves and the pain responded to nerve blocks. 

Post-Mastectomy Pain Syndrome (PMPS)

These patients present with persisting pain and sensory abnormalities following surgery. It is more common after operations involving the upper outer portion of the breast or the underarm area. Pain may be felt in axilla, inner side of upper arm, chest wall, shoulder or the surgical scar. Intercostobrachial nerve damage which can occur with axillary node dissection is considered as a common cause. 

Mastectomy patients are also at increased risk for pain in the shoulder and/or scapulothoracic area (upper back and back of shoulder area). In one study approximately 27% of patients reported such problems even after 6 months of surgery and the possible causes can include 

• Axillary web syndrome
• Adhesive capsulitis
• Myofascial dysfunction
• Brachial plexopathy 
• Rotator cuff injury

Reduced movements and guarding can lead to further decline in function, reduced lymphatic drainage and increase in pain.

What is the prognosis of post breast cancer surgery pain and what are the treatment options?

There is paucity of good quality evidence regarding the long-term outcomes in post mastectomy pain with some studies suggesting reduction in chronic pain /sensation abnormalities whereas others reporting long term persisting pain in a significant proportion of patients. Persisting pain after surgery can be multifactorial and hence besides pain management, addressing psychosocial and functional disruption, using a multimodal approach, is equally important. Some of the options used in the treatment include

Medications: These may include different classes of medications such as special types of painkillers used for nerve pain called anti neuropathic medications. These include the anticonvulsants and antidepressants which are well known painkillers.

Before starting painkillers, an assessment to identify the likely pain generators is carried out and the therapy is tailored accordingly. Sometimes even the side effects of medications are utilised to our advantage like the sedative side effect to improve sleep. There are numerous other painkillers which can be utilised like opioids, anti-inflammatory agents, topical agents (e.g. capsaicin), numbing patches, painkiller patches, oral tablets, pain relieving nasal sprays and lollipops etc. 

Physical therapy. Early initiation of physical therapy with gradual increase from range of motion exercises to active stretching, followed by strengthening is recommended. The aim is to preserve glenohumeral and scapulothoracic movement, strength, and to minimise arm dysfunction. Early initiation of physical therapy is supported by research evidence demonstrating  better range of motion at 2 years post axillary node dissection surgery.

Another subgroup that can benefit from early therapy is those experiencing pain secondary to lymphedema. Apart from physical therapy other interventions such as occupational therapy, compression garments, manual lymph drainage, lymph-reducing exercises, skin care and weight loss may also be required. 

Psychological treatments these may include options such as cognitive behavioural therapy (CBT), hypnosis, mindfulness-based therapies, meditation, self-management programs (individual vs. group) etc. Self-management programs focus on education, cognitive restructuring  to modify thought processes and reduce distress, coping skills training (e.g., pacing, communication) and relaxation training (e.g., hypnosis, mindfulness).

Interventions/ Injections– these are discussed in the next section

What other interventions can be performed for postmastectomy pain?

The most appropriate intervention is decided keeping in mind the likely pain generator. Some of the options include

Trigger point injections Muscles ability to contract and relax plays an important role in body functioning. When muscles fail to relax, they form knots or tight bands known as trigger points. Common causes include inflammation, injury of the muscle or the neighbouring structures. Injection of local anaesthetic and steroid at the points of maximal tenderness can relieve chronic post mastectomy pain. The local anaesthetic blocks the pain sensations and the steroids help in reducing the inflammation, swelling. I prefer to perform these injections under ultrasound guidance as it improves the accuracy and reduces the chances of complications. Post injection physiotherapy is essential to prevent recurrence and maximise the benefits. 

Nerve Blocks & Pulsed Radiofrequency – Intercostal, Pectoral Nerves 
Intercostal nerves run in between two ribs to supply the chest wall. They carry messages from the chest wall to the brain and vice versa. Indications for intercostal block can be diagnostic or therapeutic. The procedure involves injecting a mixture of local anaesthetic and a small amount of steroid under ultrasound guidance. Using ultrasound helps to visualise the spread of drugs and reduce the chances of complications as the needle can be kept away from important structures such as lungs. Pulsed radiofrequency treatment can be performed to prolong the effects of the injections.

Cryoablation of Nerves The primary aim in cryoablation is deactivation of the nerves transmitting the pain signals and this is achieved by freezing the nerves in a controlled fashion to temperatures as low as minus 80 degrees. The procedure is performed using a special probe called cryoprobe, which is guided to the correct location using ultrasound, x-rays and nerve stimulators. The extremely low temperatures achieved at the tip of the cryoprobe results in formation of an ice ball which freezes the nearby nerves thereby reducing pain. This technology is a minimally invasive pain-relieving alternative that does not require any cuts or incisions. It is a safe, day care procedure with the potential of providing quick and lasting relief.

Plane Blocks – Ultrasound guided Serratus Plane Block (SPB) & PECS Block
These injections are commonly used during anaesthesia for breast surgery and can sometimes be useful in chronic pain situations. They involve injection of local anaesthetics and steroids, using ultrasound guidance, in specific planes between the muscles ensuring blockage of multiple nerves with a single injection. Serratus plane block can also block the intercostobrachial nerve, which is implicated in chronic post-mastectomy pain. In chronic pain conditions they are often used to break the pain cycle enabling patients to start physiotherapy.

Botox injections
Botox injections can help in situations where muscles are the source of pain and their spasm is an issue. They can also be useful when muscle pain is produced by the temporary expander as a part of the breast reconstruction. They work by temporarily paralysing the muscles thereby producing relief. Injections are best performed under ultrasound guidance to ensure accuracy and may need to be repeated after a few months if the problem persists. 

Pulsed radiofrequency (PRF) of dorsal root ganglion (DRG)
DRG can be looked at as the modulator of the pain signals being transmitted from the periphery to the brain. By performing a block and pulsed radiofrequency procedure the pain impulses reaching the brain can be modulated/ reduced and this can produce pain relief. PRF of the DRG is considered for patients with inadequate response to other treatments discussed previously. 

Stellate Ganglion Block this can be helpful in some cases in reducing pain and improving range of shoulder movements. These injections target special nerves called the sympathetic nerves, that can get involved in transmitting the pain signals to the brain.  Sometimes a series of injections may be required to produce lasting relief. 

The post Struggling With Pain After Breast Cancer Surgery? Learn More About Post Mastectomy Pain appeared first on Dr Amod Blog.

• Cancer itself – When cancer grows it damages the tissues. It causes inflammation, unusual stretching, irritation and all this can lead to pain. Like if we talk about a pancreatic cancer, when it grows or stretches it can irritate the diaphragm (main breathing muscle) and that cause shoulder pain
• Cancer spread – when cancer grows uncontrollably then it can spread to the nearby or distant body parts like the bone, liver, kidney, lymph nodes etc.
• Associated problems like bloating, constipation, blockage of ducts, clotting problems, distention of liver or abdomen etc.
• Cancer treatments like radiotherapy or chemotherapy are known to cause nerve pain (peripheral neuropathy. Surgery may also be associated with chronic persistent pain.
• Extra stress on other body parts – Often to protect one part of our body, we put pressure on other parts for example using crutches to offload a leg may become the source of shoulder pain as the crutches place extra load on my shoulder
• Other coincidental problems – it is not necessary that all pain that every cancer patient suffers is due to cancer. There could be other coincidental problems like in the general population such as arthritis. So it is important to identify not only the type of pain but also the source of pain, before we plan treatment.

Pain related to cancer may have different components such as background pain and breakthrough pain. These need to be taken into account while making treatment plans. Let’s take an example of pain due to pancreatic cancer. These patients may have a constant pain (background pain) and there may be increased pain that comes after eating (breakthrough pain). Breakthrough pain may happen due to provoked or unprovoked factors and when we make a treatment plan it is important to have a plan for breakthrough pain.

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