The global cancer statistics in 2022 expect breast cancer (BC) to account for 31 % of all newly diagnosed tumors in women, and the mortality rate will account for 15 % of all cancers in women [1]. According to the American Cancer Society, the 5-year survival rate of BC patients from different races varies from 80 % to 92 % [2,3]. BC patients face the stress of a cancer diagnosis, a “fatal disease,” and experience the pressure of surgery, chemotherapy, radiotherapy, and other treatment methods. It is noteworthy that BC patients with intense psychological stress, such as fear of cancer recurrence, will be more doubtful about their disease and future life, exhibit severe symptom burden, and develop serious mental illnesses such as posttraumatic stress disorder [4]. Moreover, BC patients need to invest in a more extended period of treatment costs due to the improvement of the 5-year survival rate, which brings a severe economic burden to patients and their families.

Some studies have shown that financial distress in younger cancer patients was severe [5], and four years after the cancer diagnosis, 12 % of early BC patients had medical debt [6], which had a remarkable impact on the patient's mental health and quality of life [7]. In addition, as a threatening illness, BC challenges women's identity, body image, relationships with children and husbands, and self-esteem [8], thus aggravating stress, anxiety, and depression.

Increasing evidence has shown that stress is closely related to various psychological and physiological problems [9,10], but only when individuals feel environmental stimuli is stress, that is, perceived stress [11]. Perceived stress refers to the subjective feeling or psychological response that occurs when a stressful event in the environment acts on an individual and is evaluated through the integrated perception process (sensation, perception organization, judgment, and recognition stages) [12]. It is the level of subjective psychological stress that an individual experiences [11]. Compared with stress, only by focusing on the perceived stress of BC patients can we understand the impact of stress on health more deeply. Consequently, it is vital to reduce BC patients’ perceived stress.

In recent years, some scholars have carried out intervention research on reducing the perceived stress of BC patients, such as yoga [13], mindfulness-based stress reduction [14], body-mind-spirit [15], exercise [16], cognitive-behavioral stress management [17], enhanced self-regulation [18], and auricular acupuncture [19]. Nevertheless, the effects of interventions are contradictory. For example, Taylor et al. [13] explored the effect of yoga on BC patients and showed no significant change in perceived stress compared to the control group. In contrast, another RCT [20] displayed the opposite result. Moreover, most RCTs have small sample sizes, such as 24 [21], 28 [22], 31 [23], and 44 [14], which limits statistical efficiency to a certain extent. Due to the heterogeneity of results, it is necessary to elucidate the impact of interventions on perceived stress and comprehensively identify effective interventions in BC patients.

Lazarus and Folkmans’ transactional model of stress and coping clarified that when individuals perceive stress, the neuroendocrine system activates the hypothalamus-pituitary-adrenal (HPA) axis, increasing the release of inflammatory markers [24]. Considering that inflammatory markers can also reflect changes in stress, several included studies explored the impact of interventions on perceived stress and verified the impact on inflammatory markers. In addition, anxiety and depression are common in breast cancer patients, so most of the included studies verified the impact of anxiety and depression simultaneously. Therefore, this study used perceived stress as the primary outcome and anxiety, depression, and inflammatory factors as secondary outcomes. Several interventions, such as mindfulness-based stress reduction [14] and auricular acupuncture [19], explored the effectiveness of inflammatory makers but were limited to a small sample size. At the same time, interventions targeted at reducing anxiety or depression, such as mindfulness and yoga [14,15], cognitive-behavioral stress management [17], and self-regulation [18], showed different effects, even opposite results [14,15]. Hence, it is necessary to integrate results from different RCTs to verify the effects of interventions on inflammatory factors, anxiety, and depression.

A rigorous meta-analysis is necessary to address the lower statistical efficiency and inconsistent results in previous studies. However, to our knowledge, systematic reviews and meta-analyses on the effect of interventions on perceived stress in breast cancer patients are limited. Thus, this study adopts a meta-analysis method, aiming to confirm the impact of interventions on perceived stress, anxiety, depression, and inflammatory markers to identify effective interventions. This systematic review can enable practitioners to understand the current interventions for improving perceived stress, which interventions are effective or ineffective, and the limitations of current research, which can provide a reference for future new intervention research and clinical trials.