Procedure
This cross-sectional study was conducted on women with breast cancer who referred to public and private oncology centers in Tabriz, Iran for chemotherapy or radiotherapy from October to March 2020. The inclusion criteria were getting primary breast cancer based on the medical record with each stage, more than one month elapsed from the diagnosis, and undergoing chemotherapy or radiotherapy. The exclusion criteria included having a history of chronic and systemic diseases, having a history of mental disorders, having other concurrent cancers or breast cancer metastases based on the medical record, undergoing chemotherapy or radiotherapy due to the cancer recurrence, and experiencing other stressful events, such as death of relatives during the last six months.
The sample size was determined using the formula 
and calculated based on the study of Konings et al. (18). Thus, considering SD = 3.4, d = 0.05 around the mean (14.4), α = 0.05 with 95% confidence coefficient, and 20% sample drop, the sample size was calculated 166 subjects. The sampling was done using the convenience sampling method after obtaining the permission of the Ethics Committee of Tabriz University of Medical Sciences (IR.TBZMED.REC.1398.577). In the same vein, the researcher referred to the public and private oncology centers in Tabriz, evaluated the patients in terms of the inclusion and exclusion criteria, provided the information about the research objectives and confidentiality of information, and asked the eligible patients to participate in the study. The written informed consent was obtained from all participants. Therefore, 166 women with breast cancer undergoing chemotherapy and radiotherapy (83 subjects from public centers and 83 from private centers) completed the demographic and disease characteristics questionnaire, cancer worry scale, social support questionnaire, brief illness perception questionnaire, international physical activity questionnaire-short form, and the EORTC-in-patsat32 through interview in a quiet environment. Some important questions, such as the type and stage of cancer were completed from the patients’ files.
Measures
The demographic and disease characteristics questionnaire included the variables of age, educational level, occupation, family income level, insurance coverage, place of residence, marital status, number of children, type and stage of breast cancer, place of treatment, and type of surgery as well as elapsed time from the diagnosis of cancer.
The present study used the eight-item cancer worry scale (CWS) designed by Douma et al. (2010). The responses are rated on a 4-point Likert scale ranging from 1: never to 4: almost always. The scores are ranged from 8–32. Higher scores represent more worry about cancer recurrence. The Cronbach’s alpha of the tool was 0.88 (19).
The brief illness perception questionnaire (Brief IPQ) with nine items was used to assess the illness perception of women with breast cancer. The first eight items are scored on a scale of 1–10. The item nine is open-ended, questioning the three main causes of the illness. The scores are ranged from 0–80. The Cronbach’s alpha coefficient of the tool was reported to be 0.80 and the test–retest reliability was 0.75 (20).
Further, the EORTC-in-patsat32 questionnaire, developed by Bredart et al. (2004), was applied to measure the patient’s satisfaction with medical care. The questionnaire evaluates the areas of satisfaction with health care providers, and aspects of the organization of care and services. The responses are rated on a 5-point Likert scale (1: poor; 2: average; 3: good ; 4: very good; 5: excellent) and the score of each area is between 0-100 and higher score represents more satisfaction. The Cronbach’s alpha of the tool was calculated to be 0.56–0.96 (21).
The present study applied the twelve-item social support questionnaire developed by zimet et al. (1988). The multidimensional scale of perceived social support (MSPSS) is a 7-point Likert scale ranging from 1: strongly disagree to 7: strongly agree. The total score ranges from 12–84 and the higher the score, the greater the perceived social support (22). The Cronbach’s alpha of the tool was reported 0.83 (23).
In addition, the present study used the international physical activity questionnaire - short form (IPAQ-SF) with seven items during the last seven days. The physical activity level is classified into the light physical activity, like walking, moderate physical activity, such as carrying light loads, cycling at average speed, and playing volleyball, and heavy physical activity, such as lifting heavy objects, digging, like digging a garden, aerobic exercise, fast cycling, and running. For Calculating and classifying the physical activity, the metabolic equivalents (MTEs) were calculated for the aforementioned physical activities. The metabolic equivalent is considered to be 3.3 for walking, 4 for moderate activity, and 8 for vigorous activity. Then, the numbers were multiplied by the duration of performed activity (min) and the number of the days of doing that activity (24):
Metabolic equivalent (min per week) = walking (metabolic equivalent × min × day) + moderate activity (metabolic equivalent × min × day) + vigorous activity (metabolic equivalent × min × day)
The Cronbach’s coefficient of .7 was demonstrated for the Persian version of IPAQ-SF (25).
Statistical analysis
The data were analyzed using SPSS / Ver 25 software and Kolmogorov-Smirnov test was used to measure the data distributions for normality. The data were analyzed using independent t-test, Pearson correlation coefficient, and ANOVA. Then, the independent variables with P- value of less than 0.2 in the bivariate test entered into the multivariate linear regression model through Backward strategy in order to control the confounding variables.