Research on the Relationship Between Self-Management Ecacy and Quality of Life for Breast Cancer Patients Receiving Endocrine Therapy

Purpose To investigate the status quo and relationship between self-management ecacy and quality of life (QOL) of patients with breast cancer undergoing endocrine therapy, and to explore the inuencing factors of QOL. Methods The convenience sampling method was used to select 240 patients who received endocrine therapy after breast cancer surgery in the First the self-designed general data questionnaire, self-management ecacy questionnaire for breast cancer patients with endocrine therapy and quality of life scale for breast cancer patients were used to investigate. The frequency, percentage, mean ± standard deviation were used to describe patients' self-management ecacy and quality of life. Pearson correlation analysis was used to analyze the relationship between self-management ecacy and quality of life, and univariate analysis and multiple stepwise regression were used to analyze the inuencing factors of QOL. The scores of self-management ecacy and QOL of patients with breast cancer endocrine therapy were 125.21 ± 25.57 and 153.33 ± 19.31 respectively, which were at the middle level; self-management ecacy was signicantly positively correlated with quality of life ( p < 0.01 ) ; multiple stepwise regression results showed that self-management ecacy, the number of physical symptoms, monthly family income and recurrence and metastasis were the inuencing factors of QOL. Self-management ecacy breast cancer therapy.


Introduction
Breast Cancer (BC) is the most common malignant tumor in women worldwide [1] and also causes the largest number of deaths among women worldwide [2]. The latest global cancer burden data released by THE World Health Organization/International Agency for Research on Cancer (WHO/IARC) in December 2020 [3] showed that the number of new cases of breast cancer in 2020 was as high as 2.26 million (11.7% of the newly diagnosed cancer), and the number of deaths was more than 680,000 (6.9%). In China, the number of new cases of breast cancer reached 426,000, with 117,000 deaths. The incidence and mortality rate of breast cancer are still rising [3,4].
Endocrine therapy for breast cancer mainly reduces or clears estrogen levels in the body through some drugs or treatments, thereby inhibiting the growth of breast cancer and reducing the risk of recurrence and metastasis [5,6], which plays an important role in the comprehensive treatment of breast cancer [7]. Studies [8][9][10][11][12] show that most patients with endocrine therapy for breast cancer have experienced hot ashes, night sweats, insomnia, joint stiffness, weight gain, anxiety, depression and other symptoms, and the long treatment cycle will make patients become depressed and indifferent. Therefore, in the process of treatment and rehabilitation of patients with breast cancer endocrine therapy, it is particularly important for patients to actively participate in the management of the disease and establish an effective self-management model. Self-e cacy is a core concept in self-management theory, and studies have con rmed that the self-management behavior of breast cancer patients is affected by selfe cacy, and the higher the level of self-e cacy, the better the self-management behavior [13]. Based on the endocrine therapy of breast cancer patients quality of life of the related research is less involved in self-management e cacy problems, this study aims to investigate the status quo of self-management e cacy and quality of life of breast cancer patients undergoing endocrine therapy, clarify the relationship between self-management e cacy and QOL, and provide reference for the formulation of nursing intervention programs to improve patients' selfmanagement e cacy and improve patients' QOL.

Participants
From May 2016 to September 2016, convenience sampling method was used to select patients who received endocrine therapy after breast cancer surgery in the Department of Breast Surgery of the First A liated Hospital of China Medical University as the research subjects. Inclusion criteria: pathological diagnosis of breast cancer and postoperative endocrine therapy for more than 1 month; above 18 years old; complete cognitive and behavioral abilities; patients were willing to participate in the study with informed consent. Exclusion criteria: combined with more serious cognitive and mental disorders; combined with complicated diseases that seriously affect the quality of life.

Sample size
In multi-factor analysis, 10 times of the independent variable is considered appropriate. There were 20 independent variables in this study, and 20% invalid questionnaires should be considered. The nal sample size was 240 cases. Invalid questionnaire criteria: more than 20% of the items in the whole questionnaire are not answered; the whole questionnaire was wavy or monosyllabic.

Data collection and measurements
General Data Questionnaire It was designed by researchers themselves, including demographic data (age, height, weight, race, level of education, employment status, lifestyle, marital status, monthly family income, medical payment method, etc.) and disease related information questionnaire (postoperative time, start time of endocrine therapy, menstrual status, physical symptoms, complications, recurrence, metastasis, etc.).
Self-management e cacy questionnaire for breast cancer patients undergoing endocrine therapy [14] The questionnaire consisted of 33 items from 4 dimensions, including 9 items of life/emotion, 7 items of disease coping, 9 items of society/family and 8 items of compliance behavior.Likert5-level scoring method was used in the questionnaire, ranging from "no con dence" to "very con dence", and the higher the score, the higher the level of selfmanagement e cacy. The Cronbach's α coe cients of the total questionnaire were 0.972, and the Cronbach's α coe cients of the four dimensions ranged from 0.895 to 0.949. The I-CVI of the questionnaire ranged from 0.80 to 1.00 and the S-CVI was 0.966. The retest reliability was 0.913.
Quality of Life Instruments for Patients with Breast Cancer QLICP-BR) [15,16] The scale developed by the Chinese scholars Chong-hua Wan, combined with China's economic and cultural background and value system, specially for measuring the breast cancer patient health related quality of life, a total of 39 items, consisted of the common module QLICP -GM and breast cancer speci c entry form; using Likert 5 grade evaluation method, from "no" to "very" count 1-5 points, respectively. There are both positive and negative scoring items in the scale. The higher the score of the positive item, the better the quality of life; the higher the score of the negative item, the worse the quality of life. The Cronbach's α coe cient of internal consistency of social dimension was 0.58, and the other dimensions were greater than 0.65. The retest reliability of the scale was 0.88. In addition, some studies have proved that the internal consistency Cronbach's α coe cient of this scale is 0.81 [17].

Survey methods
Questionnaire was distributed by the researcher himself. Before the investigation, researcher explained the purpose and signi cance of the study to the patients, promised to keep their information strictly con dential, and the patients signed the informed consent form. In the process of lling in the questionnaire, patients' questions were answered in time. For those patients who were not convenient to ll in the questionnaire by themselves or had poor eyesight, the researcher read the questions for the patients one by one, and then the patients answered by themselves or the researcher recorded their answers. The questionnaire was lled in anonymously, and was taken back on the spot after lling in, and checked whether there was any missing content. If there was any missing or unclear content, the questionnaire was returned to the patient in time for checking and lling to ensure the integrity of the results.
Statistical analysis SPSS 20.0 software was used for statistical analysis. Descriptive statistics included frequency, percentage, mean and standard difference, etc. and inferential statistics included T test, Pearson correlation analysis, one-way ANOVA and multiple step-up regression analysis, etc. P<0.05 was statistically signi cant.

Results
A total of 300 questionnaires were sent out and 240 were effectively received with effective recovery rate of 80%. All subjects were female, aged between 30 and 78 years old, with an average age of 52.89±9.67 years old.
Status quo of self-management e cacy of patients undergoing endocrine therapy for breast cancer The average score of self-management e cacy of patients undergoing endocrine therapy for breast cancer was 125.21±25.57, among which 48.3% of patients with total score higher than the average were in the middle level (Table  1). The average score of QOL of breast cancer patients treated with endocrine therapy was 153.33 ± 19.31, and 54.2% of them were higher than the average score, which was generally in the middle level( Table 2). Correlation between self-management e cacy and quality of life in breast cancer patients undergoing endocrine therapy The total score of self-management e cacy and all dimensions were signi cantly positively correlated with the total score of quality of life (p<0.01), self-management e cacy was signi cantly positively correlated with physical function, physiological function, social function and breast cancer speci c modules of quality of life (p<0.01)( Table  3).  Multivariate analysis of quality of life of breast cancer patients treated with endocrine therapy QOL as a dependent variable, the single factor meaningful variables of age, BMI, marital status, family income, the number of somatic symptoms and types, fatigue, nausea, insomnia, whether metastasis and recurrence selfmanagement effectiveness as independent variables, multiple stepwise regression analysis, the results showed that there were four signi cant variables included in the regression equation, namely, self-management e cacy, number of physical symptoms, monthly family income, and recurrence and metastasis, which jointly predicted 46.2% of the variance in quality of life, in which self-management e cacy alone explained 33.6% of the variance (Table 5).
Regression equation: Y' QOL =5.445X Self-management e cacy -3.337X number of physical symptoms +2.144X monthly family income -8.660X recurrence and metastasis +61.255 The total score of the questionnaire on self-management e cacy of endocrine therapy for breast cancer patients was 165.00 points. In this study, the average score of the self-management e cacy of breast cancer endocrine therapy patients was 125.21 points, which was at a medium level and consistent with previous research results [18][19]. Studies have shown that the course of disease will affect the level of self-management e cacy of patients, and the level of self-management e cacy of patients will decrease with the passage of time [20]. Therefore, in this study, patients were divided into 1 year, 2 years, 3 years, 4 years, 5 years and more than 5 years according to the length of endocrine therapy for comparison. However, the results showed that there was no signi cant difference in the scores of self-management e cacy among patients with different periods of endocrine therapy (p>0.05), which may be due to the good physiological and psychological status of most patients with endocrine therapy in this study, and the adequate family and social support system, which made patients con dent to adhere to long-term treatment.
QOL status quo in patients with endocrine therapy of breast cancer of breast cancer The average score of QOL of breast cancer patients treated with endocrine therapy was 73.29, which was at a medium level, consistent with the results of Montagnese et al. [21]. Among all the dimensions, the score of psychological function was the lowest, which may be related to breast cancer patients' inferiority about the change of their own image, the worry about the disease and treatment, and the symptom confusion caused by endocrine therapy.
Correlation between self-management e cacy and QOL in patients with endocrine therapy of breast cancer The results of this study showed that there was a positive correlation between self-management e cacy and quality of life (p<0.01), which indicated that the higher the level of self-management e cacy, the better the QOL, which was consistent with previous research results [18, [22][23][24]. At the same time, the results of this study showed that the selfmanagement e cacy of patients with breast cancer endocrine therapy was positively correlated with the physical function dimension, physiological function dimension, social function dimension and breast cancer-speci c module of QOL (p<0.01), which indicated that improving the self-management e cacy of patients with breast cancer endocrine therapy can improve their physical, physiological and social function and other aspects of life quality.
However, in the results of this study, the common symptoms and side effects of self-management e cacy and QOL were not related, which may be due to the difference between the symptoms and side effects contained in the dimension of QOL scale for breast cancer patients and the physical symptoms and side effects experienced by breast cancer patients during endocrine therapy. In addition, the life/emotion dimension, disease coping dimension, social/family dimension and compliance behavior dimension of self-management e cacy were positively correlated with the quality of life (p<0.01), which indicated that when the self-management e cacy level of daily life and emotions is high, positive emotions can be improved while negative emotions can be reduced to broaden the patient's thinking-behavior system and establish an effective coping mode [23,25], so as to better cope with diseases and achieve social and family functions. In addition, breast cancer patients with a strong sense of self-e cacy can face the stress caused by the disease with a more optimistic and positive attitude, actively seek the help of medical staff and the support of family and society, build up con dence in ghting the disease, actively participate in the management of the disease, and reduce the in uence of disease and treatment on the overall health and QOL [26][27].

Analysis of in uencing factors of QOL in patients with endocrine therapy of breast cancer
In this study, the factors in uencing the QOL of patients with breast cancer undergoing endocrine therapy were analyzed by one-way ANOVA, and it found that age, BMI, marital status, monthly family income, the number and types of physical symptoms, fatigue, nausea, insomnia, recurrence and metastasis and self-management e cacy had signi cant in uence on the QOL (p<0.05).
Because single factor analysis can't control the in uence of confounding factors and the information obtained from comprehensive analysis, the comparability of data is slightly poor and the results are relatively limited. Multi-factor analysis has the characteristics of high e ciency and reliable results, and through comprehensive analysis, it can eliminate atypical and unrepresentative factors and nd out the real factors. Therefore, in order to eliminate the possible interaction among various factors, this study took the QOL as the dependent variable, and meaningful variables in single factor analysis as the independent variable, and carried out multiple stepwise regression analysis to screen the most important in uencing factors of the QOL of breast cancer patients undergoing endocrine therapy.
The results showed that the variables entered the regression equation were self-management e cacy, number of physical symptoms, monthly family income, recurrence or metastasis, which jointly predicted the variation of 46.2% of the QOL of patients with breast cancer undergoing endocrine therapy. It was suggested that the higher the selfmanagement e cacy level of breast cancer endocrine therapy patients, the better the QOL, which was consistent with the previous research results [18, [22][23][24]28]. Bandura [29] thought self-e cacy can affect human health by in uencing individual's physical and mental regulation system, such as in uencing individual's health habits and directly controlling individual's physiological aging. Therefore, self-e cacy can make breast cancer patients reach the physiological, psychological and social health state by regulating the physical and mental system, thus affecting their quality of life. Patients with high self-e cacy, when faced with di culties and challenges, often don't fear di culties, often can make their ability to solve problems outstandingly, show better self-management ability, better grasp the relevant knowledge and skills of self-management healthy behaviors, adhere to daily life and emotional management, adhere to self-condition monitoring, adhere to correct self-management behaviors and improve their quality of life; on the contrary, patients with low self-e cacy often question their abilities and tend to adopt negative or evasive coping styles when facing diseases, which easily leads to the generation of bad emotions such as anxiety, depression, pessimism, disappointment, etc., which is not conducive to the formation of correct self-management behaviors and new healthy behaviors, and leads to the decline of quality of life [22,26,28,[30][31]. Secondly, the number of physical symptoms, family monthly income and whether recurrence or metastasis also enter the regression equation. The fewer physical symptoms, the higher monthly income of family, and the better QOL if there is no recurrence or metastasis [26, [32][33][34][35].
To sum up, the self-management e cacy of breast cancer patients undergoing endocrine therapy is the most important factor affecting their QOL. The higher the self-management e cacy level of breast cancer patients, the better their QOL.

Conclusion
Self-management e cacy and QOL of patients with breast cancer undergoing endocrine therapy are in the middle level, and self-management e cacy is positively correlated with QOL. Self-management e cacy of breast cancer patients undergoing endocrine therapy is an important factor affecting their QOL. In nursing work, we should pay attention to the status of self-management e cacy of breast cancer patients, and take corresponding nursing measures to help patients improve their self-management e cacy, self-management behavior and treatment compliance, so as to prolong their lives and improve their QOL.

Declarations
Funding: Liaoning Province Science and Technology Planning project (No.2015225023) Con icts of interest: The researchers declare no con ict of interests.
Availability of data and material: Data and material are available upon request.
Code availability: The IBM SPSS statistics 20.0 was utilized to analyze the data.
Authors' contributions: All authors contributed to the study conception and design. Material preparation, data collection, analysis were performed and the rst draft of the manuscript was written by Hongjie Yi. All authors commented on previous versions of the manuscript. All authors read and approved the nal manuscript.