Acupressure for Preventing Post-Operative Pain and Opioid Use Among Breast Cancer Patients Receiving Surgery

Chronic pain following breast cancer surgery is a significant problem for women. There are over 3 million women in the United States living as breast cancer survivors. Sustained post-surgical pain is one of the most troubling side-effects for these women and continues to affect around 25-60% of breast cancer survivors, with approximately half classifying pain as being moderate to severe. Chronic cancer-related pain is associated with increased fatigue, depression, anxiety, sleep disruption, and decreased quality of life and function.

Acute pre- and post-operative pain are significant predictors of sustained pain following breast cancer surgery, but are insufficiently managed. The etiology of persistent breast cancer related pain following surgery is multifactorial and may be the direct effect of cancer or cancer treatment (e.g. surgery). Known risk factors for this chronic pain include younger age, higher body mass index, type of surgery (axillary lymph node dissection), and presence of a mood disturbance. Cancer patients may develop pain from neurotoxicity from adjuvant chemotherapy, and radiation may also play a role, and causes persistent pain in 13 - 26% of patients.

Two of the most significant factors that determine persistent pain following breast cancer surgery are the degree of pre-surgical pain and acute post-surgical pain. Recent reports have suggested that treatments aimed at reducing these factors may be effective at preventing the development of chronic pain following breast cancer surgery. Existing pre-emptive treatments to reduce this acute surgical pain include the use of nerve blocks and/or pharmacologic agents such as opioids, NSAIDs, ketamine, and gabapentin. While some pharmacologic approaches yield clinically meaningful reductions in post-operative pain in the research setting, there remains controversy in the field. For example in breast surgery specifically, a recent meta-analysis showed that thoracic paravertebral blocks have a statistically significant effect on reducing chronic pain, but the effect was not clinically meaningful and was associated with procedural risks such as vascular puncture.

In addition to the risk of developing pain following breast cancer surgery, women also report increased acute and chronic surgical pain following breast reconstruction surgery. In one of the first studies to examine pain post-reconstruction surgery, Wallace et al. found that the incidence of pain one year following breast cancer mastectomy plus reconstruction was 49% as compared to 31% for mastectomy alone. This increase was both statistically and clinically significant, and remains a current undertreated problem. Overall many women develop persistent pain after breast cancer surgery following either tumor removal or breast reconstruction. We know that this is influenced by acute pre- and post-surgical pain, but unfortunately the existing measures available for clinicians to prevent persistent post-surgical pain are not adequate.

Opioids are commonly used analgesics in the perioperative surgical setting; however, they are accompanied by significant limitations. Opioids are the most common pharmacologic intervention used for acute perioperative surgical pain. They are known to decrease pain via activation of specific receptors (mu, delta, and kappa), which inhibit neuronal firing resulting in reduced nociceptive activity. Although widely prescribed there are significant limitations for opioid use including tolerance, addiction, diversion, and even mortality. There were over 33,000 opioid deaths in the US in 2016 alone and the majority of these have been from opioid prescriptions. The US is currently experiencing an opioid epidemic wherein Americans constitute only 5% of the global population yet we consume over 80% of the world's opioid supply. Unfortunately, while opioids are needed in the surgical setting, the problem of increased opioid use is itself compounded by surgery. Patients receiving even low-risk surgeries are 44% more likely to become de novo long-term opioid consumers. With respect to breast cancer surgery, the odds of developing chronic opioid consumption following mastectomy increases by approximately 300%. Although the reason(s) for developing chronic opioid consumption are largely unknown, patients that receive a new opioid prescription within 7 days post-surgery, as compared to those who do not, are more likely to still be receiving opioids one year out. Thus acute pre-surgical and post-surgical pain, in addition to being risk factors for persistent chronic pain, may also increase the probability of becoming a chronic opioid consumer. There is an unmet need for analgesic interventions that are opioid sparing in the breast cancer surgical setting. This study proposes that acupressure may be one such option.