The breast cancer is the second leading cause of death in women (
1). It is estimated that by 2020, 70 percent of new cases of breast cancer will be observed in developing countries (
2). The International Association for the Study of Pain (IASP) reported that the prevalent of pain in breast cancer is between 40% to 89% (
3) and 17 million people complain of cancer pain.
Cancer pain or cancer treatment side effects impact on 50 to 90 percent of the patients (
4). This leads to emotional disturbance and consequently decrease quality of life in patients (
5). Cancer pain is affected by the neuropathic, psychological, social and spiritual variables and ends to social dysfunction (
6). Pain is a multidimensional phenomenon. According to the International Association of Pain, pain is defined as an unpleasant emotional experience associated with actual or potential tissue damage and has sensory and emotional dimension. Sensory aspects of pain refers to severity of pain and emotional dimension refers to amount of an unpleasant emotional experience (
7). In other words, pain is what a patient expresses as long as he experiences it. This definition emphasizes psychological concept of pain and its control (
8). Pain is a breakdown situation so that not only confronts the patient with pain distressing experience but also is related to many stressful factors which impact other different parts of patient’s life. Therefore, living with chronic pain requires tolerating emotional stress. Also, pain reduces the person’s emotional and emotional abilities. The persistent desire of the individual to escape from the pain is often unattainable. This ultimately leads to frustration and depression, which weakens the patient’s morale (
9).
On the other hand, Cancerous crises have a negative effect on the patient’s response to pain and even her healing (
10). Several drug therapies have been used to reduce cancer pain such as non-steroidal analgesics, opiate painkillers (
11), and antidepressants (
12,
13). However, these drug agents often do not completely resolve all signs of mental stress or pain. Since these drugs are mostly consumed in the long term produce a range of side effects (
14). Hence, non-pharmacological strategies which are widely used in pain management and emotional distress management are applied (
15). One of the most famous interventions is mind meditation which is rooted in Buddhism teaching (
16). From acceptance and commitment therapy perspective which is the integration of consciousness and the principles of cognitive behavioral therapy, human suffering is rooted in mental flexibility which is made through cognitive defusion and experiential avoidance. What is considered harmful is the tendency to absorb experiences and combat them by experiential avoidance (
17). Acceptance and commitment therapy is a special treatment process “psychological flexibility” which focuses on behavioral changes not reducing the symptoms (
18). The main purpose of this approach seeks to undermine excessive struggle with anxiety and experiential avoidance attempts to down-regulate and control unwanted private events (thoughts, images, bodily sensations). The goal is to enhance more flexible and mindful ways of relating to anxiety so individuals can pursue life goals important to them (
19). In this approach as soon as thoughts, feelings, memories, etc. were labels as signs and symptoms a struggle arouse among them. This is because these symptoms are defined as a traumatic and ailmental phenomenon. Acceptance and commitment change the relationship between emotions and problematic thoughts so that people do not perceive them as symptoms and even learn to understand them harmlessly (
20). In fact, there is less focus on symptoms and more focuses on improving quality of life (
21). In a randomized trial, the results showed that an acceptance-based approach was effective on the mood and quality of life of breast cancer patients (
22). In a meta-analysis evidence-base evaluation with 60 randomized controlled trials on psychiatric disorders, somatic disorders, and stress at work the results revealed that the success of this approach for chronic pain is more effective than anxiety and depression. That is to say ACT is not yet well-established for any disorder (
23). In another study the effectiveness of applied relaxation and acceptance and commitment therapy in a randomized, controlled clinical trial with a sample size of 60 chronic pain patients was compared. The results showed that the ACT approach with regard to its role as psychological flexibility as a mediating factor to reduce severity of pain is more effective than applied relaxation (
24). The recent researches on acceptance and commitment therapy show that this treatment can be an appropriate treatment for chronic pain (
25,
26). On the other hand, since acceptance and commitment interventions have shown significant advances in psychological components such as quality of life and mental flexibility, as well as reduction of symptoms in distress, emotional disturbances, and physical pain in cancer patients (
27).