INTRODUCTION
Cancer is a major global health issue, with breast cancer being the most common cancer among women worldwide. The incidence and survival rates vary significantly across different regions. In Iran, the incidence of breast cancer is high, and it affects Iranian women at a younger age, compared to their counterparts in other countries. This study investigates the social burden of cancer and its impact on individuals’ health, particularly focusing on breast cancer patients who often undergo chemotherapy or radiation therapy. It highlights the prevalence and severity of pain experienced by cancer patients, which affects their quality of life and social interactions. Additionally, it mentions the use of opioid medications for cancer pain management, along with the emphasis on non-pharmacological pain management approaches recommended by national cancer networks. Complementary therapies, such as therapeutic massage, specifically Shiatsu massage, are discussed as potentially beneficial for alleviating physical, emotional, and psychological symptoms associated with cancer and its treatment. It also mentions the adoption of Shiatsu massage as a relatively safe treatment option in cancer care, as evidenced by its implementation in hospitals in London since 2005 without reported side effects. There is no evidence of the effectiveness of Shiatsu on pain in breast cancer patients undergoing chemotherapy, and the need for high-quality studies regarding its efficacy remains essential. According to the data evaluating the effectiveness of pain management, it has been shown that pain relief significantly improves patients’ perception of cancer treatment. This study aimed to investigate the effectiveness of Shiatsu massage in improving the pain of breast cancer patients during chemotherapy.

METHODS
A randomized controlled trial was conducted Ayatollah Khansari Hospital in Arak, Iran, from June 2021 to January 2022. The sample size was calculated based on the findings of a similar study and considering the confidence interval. With a confidence level of 95%, a power of 80%, and an attrition rate 10%, the final sample size was 70 participants. The samples were selected using the convenience sampling method, and those who met the inclusion criteria were randomly assigned to two groups of intervention (A) and control (B). The inclusion criteria were having a minimum and maximum age of 18-60 years, being diagnosed with with stage II, III, or IV by the treating physician, and having full consciousness. On the other hand, the participants who died during the study or experienced acute pain at the time of questionnaire completion were excluded from the study. The final sample size was 35 individuals in each group.
Data were collected after obtaining ethical approval and informed consent. Pain intensity was measured using the Visual Analogue Scale (VAS), ranging from 0 (no pain) to 10 (worst possible pain). Pain scores were categorized as mild (1–3), moderate (4–6), and severe (7–10). Measurements were taken at two time points: before and after the intervention. Demographic and clinical information was also collected. In the intervention group, Shiatsu massage was administered during chemotherapy infusion by a trained practitioner who had completed a 12-hour training course. The massage began 15 minutes after the onset of drug infusion and lasted 20 minutes in total (three 5-minute massage sessions with two 2-minute breaks). In the control group, a mock massage involving light touch without pressure was applied for the same duration. The outcome assessor was aware of the group assignments; therefore, the study was single-blind.
The obtained data were then analyzed using SPSS software (version 16). Normality was checked using the Kolmogorov–Smirnov test. Depending on data distribution, parametric or non-parametric tests were employed. Analysis of covariance (ANCOVA) was used to adjust for baseline pain intensity, and chi-square or Fisher's exact tests were applied for categorical variables. A P-value of <0.05 was considered statistically significant.

RESULTS
The mean pain scores before the intervention were 6.83±2.43 and 4.91±2.54 in the intervention and control groups, respectively, indicating a statistically significant difference between the two groups (P=0.002). After the intervention, the corresponding scores were obtained at 3.26±1.9 and 5.83±2.68 in the intervention and control groups, respectively, showing a statistically significant difference between the two groups (P=0.0001). The mean pain score in the intervention group decreased from 6.83±2.43 to 3.26±1.9, which is significant (P=0.0001). Additionally, in the control group, the mean pain increased from 4.91±2.54 to 5.83±2.68, which is significant (P=0.006). The mean pain reduction in the intervention group is 3.571±2.38 units, and the mean pain increase in the control group is 0.914±1.85 units. For further investigation and controlling the confounding effect of baseline pain scores, an analysis of covariance (ANCOVA) was conducted. The adjusted mean in the control group was 6.373±0.326, and in the intervention group, it was 2.712±0.326, indicating that the pain score in the intervention group is significantly lower than that in the control group (P=0.039). Different levels of pain before intervention show a statistically significant difference between the two groups (P=0.006). Additionally, after intervention, different levels of pain in the control and intervention groups showed a statistically significant difference (P=0.002). Wilcoxon test results also indicate significant changes in pain levels in both groups (P<0.05). In the intervention group, initially, 21 individuals had severe pain, 9 had moderate pain, and 5 had mild pain; however, after the intervention, these numbers changed to 3 with severe pain, 11 with moderate pain, and 20 with mild pain. In the control group, initially, 8 individuals had severe pain, 15 had moderate pain, and 12 had mild pain, which changed to 13 with severe pain, 14 with moderate pain, and 7 with mild pain after the intervention. Improvement is observed in both groups; however, the degree of improvement is higher in the intervention group.

CONCLUSION
The present study aimed to determine the effect of Shiatsu massage on the level of pain in women with breast cancer during chemotherapy, and the results of this study indicate the effectiveness of Shiatsu massage on pain relief in women with breast cancer during chemotherapy. Our findings are consistent with the results of a study by Suarez et al. in 2018, where the mean pain in women with cancer undergoing chemotherapy was lower in the intervention group after Thai massage, compared to the control group (P>0.05). In line with our study, Souza et al. performed hand massage on cancer patients undergoing chemotherapy, resulting in improved pain scores in the intervention group, compared to the control group; however, this change was not statistically significant in our study. Brown conducted a study evaluating Shiatsu massage for cancer patients and found significant improvement in overall symptom scores and pain after palliative interventions.
Further investigations revealed that several studies have examined the effect of Shiatsu massage on pain relief in other groups, yielding similar results to our study. Kuboashi, in a randomized controlled study on chronic low back pain, found no significant difference between the two groups until the eighth week.
The present study aimed to determine the effect of Shiatsu massage on the level of pain in women with breast cancer during chemotherapy. The results of our study indicate the effectiveness of Shiatsu massage in reducing pain in women with breast cancer during chemotherapy. Our findings are consistent with the results of studies by Kuboashi et al. and Brown et al., which showed a significant improvement in pain levels in the Shiatsu intervention group, compared to the control group. However, the duration of intervention in our study was shorter, whereas Kuboashi et al. conducted interventions over 10 consecutive days, resulting in stronger effects.
Furthermore, a study by Filanowski et al., similar to the present study, demonstrated the efficacy of Shiatsu massage on pain relief in cancer patients. However, they performed the intervention more frequently (eight times), compared to our study. Additionally, this study showed a significant improvement in pain levels in the majority of participants after Shiatsu massage, similar to the findings of Siallahi et al., where most participants experienced a decrease in pain intensity after massage.
The present study suggests that Shiatsu massage is an easy, non-invasive, and safe intervention that can reduce pain in women with breast cancer undergoing chemotherapy. Shiatsu massage requires no special equipment, is easily performed in a short time, and is readily accepted by patients. Therefore, it is recommended to use Shiatsu massage in women with breast cancer undergoing chemotherapy, and the method of implementation should be taught to patients, their families, especially caregivers, and nurses.
To obtain stronger evidence regarding the effects of Shiatsu massage on pain, further studies with larger sample sizes, longer intervention periods, and consideration of more confounding variables, such as supportive systems, and arrangements of variables that may affect comfort should be designed.

Ethical Considerations
Compliance with ethical guidelines
The study protocol has been approved by the Ethics Committee of Arak University of Medical Sciences (Ethical ID:1398.091REC.ARAKMU.IR) and registered in the Iranian Registry of Clinical Trials (IRCT registration number: 2N20151002024290IRCT). Initially, the study objectives were explained to all participants, and written informed consent was obtained. All patients participated in the study voluntarily.
 

Funding
This study is the result of a research
project with the registration number: 1398.091REC.ARAKMU.IR, and was supported financially by the Vice Chancellor for Research and Technology of Arak University of Medical Sciences.

Authors’ Contributions
The authors contributed equally to the conceptualization and writing of the article. All of the authors approved the content of the manuscript and agreed on all aspects of the work.

Conflict of Interest
According to the authors, there is no conflict of interest associated with this article.

Acknowledgments
The researchers would like to express their gratitude to the Vice Chancellor for Research of Arak University of Medical Sciences, the
esteemed staff of the Hematology Department at Khansari Hospital, and especially those who assisted the researchers