Chronic post-treatment pain in breast cancer – where do we stand?

14 Jul 2015  |  Print

Chronic post-treatment pain in breast cancer – where do we stand?

Breast cancer treatment has come a long way, and patients live longer than ever before. For example, UK data reveal an improvement in 5-year survival from just 53% in the early 1970s to 87% now.[1] This is great news for patients and their healthcare providers. However, for those that do survive, the treatment of breast cancer can have damaging physical and psychological consequences.

Chronic pain is one such consequence – and is surprisingly common.

In a recent analysis of breast patients, conducted at 12 months post-surgery, 66% reported persistent pain.[2] Similarly, in a nationwide study of >3,000 Danish women 2-3 years after surgical treatment and adjuvant therapy for breast cancer, almost half (47%) reported pain.[3] Among these, the pain was severe in 13% of cases, and moderate in a further 39%.

This pain often continues into the long term. When the same Danish cohort was followed up again at 5-7 years post-surgery, 37% still reported pain.[4] Furthermore, the problem was not static, as the pain sometimes either progressed or regressed with time: among women reporting pain at 2-3 years, one third were no longer suffering at 5-7 years, while one-sixth of the women who did not have pain at 2-3 years did report it at 5-7 years.[4]

Defining chronic pain

How can we define ‘chronic pain’ in the context of breast cancer treatment? Broadly, it should meet the following three criteria:[4]

  • Located in or around the treated area;
  • More than 3 months after the last treatment;
  • When other causes, such as recurrence, have been ruled out.

The consequences of this pain can be far-reaching, even affecting basic levels of functioning. For many patients, post-treatment pain impacts on activities as fundamental as sleeping, dressing, doing the laundry, and carrying groceries.[5]

Risk factors for chronic pain after breast cancer treatment

Multiple components have been linked with an increased risk of chronic pain. These are typically divided into patient- and treatment-related factors:

Patient-related factors

Several patient features have been linked with chronic pain after breast cancer treatment. For example, age is a significant factor – the prevalence and intensity of pain and sensory disturbances is typically higher in younger patients.[6,7]

In addition, in surgical breast cancer patients, pre-operative pain has been associated with an elevated risk of persistent post-treatment pain.[2,7] Further studies are required to determine whether treatment of pre-operative pain can prevent the development of post-surgical problems.[7]

Another modifiable risk factor that predicts chronic pain in surgical patients is acute post-operative pain.[6,7] Efforts to improve post-operative pain management are therefore required, as this may reduce the occurrence of chronic pain.[7]

Pain complaints in other parts of the body are also associated with an increased risk of chronic pain following breast cancer surgery.[3,4] For example, in a survey of more than 2,000 women, those reporting pain in a non-surgical area had more than double the risk of chronic post-treatment pain.[4]

Finally, a range of psychosocial factors have been linked with long-term pain. In a prospective study of 362 women undergoing surgery for primary breast cancer, pre-operative psychological ‘robustness’ – a composite variable comprising high optimism, high positive affect and low emotional distress – was protective against chronic pain.[6] Furthermore, pre-operative depression, anxiety and catastrophizing have all been significantly associated with an elevated risk of post-treatment pain.[2,7,8]

Treatment-related factors

Certain types of breast cancer therapy appear to be more associated with chronic pain than others. For example, a recent systematic review identified axillary lymph node dissection (ALND) as a procedure with an elevated risk of chronic pain.[9]

Similarly, radiotherapy can cause nerve damage and is associated with an increased risk of chronic pain.[2] However, the choice of technique may be important. In a comparison of intra-operative radiation therapy (which has a small radiation field) versus external-beam radiation therapy (which has a relatively broad field), the former was associated with a lower pain prevalence: 25% versus 34%, respectively.[10] However, this trend did not achieve statistical significance (p=0.11).

Finally, some chemotherapy is commonly associated with neurotoxicity.[11] It has also been linked with chronic pain after breast cancer treatment, although the available data are contradictory – some studies suggest an association,[2] but others show no link.[3,12]

Managing chronic pain – a dearth of evidence

There is currently a lack of high-quality procedure-specific evidence on the reduction of chronic pain after breast cancer treatment. For example, in a systematic review of neural blockade, only seven studies were identified; the quality of these studies was found to be low and the efficacy data were inconclusive.[13] Hence, there is a need for more research into the treatment and prevention of chronic pain following breast cancer therapy.

This issue will become increasingly pressing as more patients experience long-term survival following their treatment. For these women, it is essential that we strive to optimize their quality of life by minimizing chronic pain.

References:

  1. 1. Cancer Research UK. Breast cancer survival statistics. Available at: www.cancerresearchuk.org/cancer-info/cancerstats/types/breast/survival/breast-cancer-survival-statistics#Trends. Accessed February 2015.
  2. 2. Meretoja TJ, Leidenius MH, Tasmuth T, et al. Pain at 12 months after surgery for breast cancer. JAMA 2014;311:90-92.
  3. 3. Gärtner R, Jensen MB, Nielsen J, et al. Prevalence of and factors associated with persistent pain following breast cancer surgery. JAMA 2009;302:1985-1992.
  4. 4. Mejdahl MK, Andersen KG, Gärtner R, et al. Persistent pain and sensory disturbances after treatment for breast cancer: six year nationwide follow-up study. Br Med J 2013;346:f1865.
  5. 5. Andersen KG, Christensen KB, Kehlet H, Bidstup PE. The effect of pain on physical functioning after breast cancer treatment: development and validation of an assessment Tool. Clin J Pain 2014. [Epub ahead of print].
  6. 6. Bruce J, Thornton AJ, Powell R, et al. Psychological, surgical, and sociodemographic predictors of pain outcomes after breast cancer surgery: a population-based cohort study. Pain 2014;155:232-243.
  7. 7. Miaskowski C, Cooper B, Paul SM, et al. Identification of patient subgroups and risk factors for persistent breast pain following breast cancer surgery. J Pain 2012;13:1172-1187.
  8. 8. Belfer I, Schreiber KL, Shaffer JR, et al. Persistent postmastectomy pain in breast cancer survivors: analysis of clinical, demographic, and psychosocial factors. J Pain 2013;14:1185-1195.
  9. 9. Andersen KG, Kehlet H. Persistent pain after breast cancer treatment: a critical review of risk factors and strategies for prevention. J Pain 2011;12:725-746.
  10. 10. Andersen KG, Gärtner R, Kroman N, et al. Persistent pain after targeted intraoperative radiotherapy (TARGIT) or external breast radiotherapy for breast cancer: a randomized trial. Breast 2012;21:46-49.
  11. 11. Hershman DL, Weimer LH, Wang A, et al. Association between patient reported outcomes and quantitative sensory tests for measuring long-term neurotoxicity in breast cancer survivors treated with adjuvant paclitaxel chemotherapy. Breast Cancer Res Treat 2011;125:767-774.
  12. 12. Andersen KG, Jensen MB, Kehlet H, et al. Persistent pain, sensory disturbances and functional impairment after adjuvant chemotherapy for breast cancer: cyclophosphamide, epirubicin and fluorouracil compared with docetaxel + epirubicin and cyclophosphamide. Acta Oncol 2012;51:1036-1044.
  13. 13. Wijayasinghe N, Andersen KG, Kehlet H. Neural blockade for persistent pain after breast cancer surgery. Reg Anesth Pain Med 2014;39:272-278.

 

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