Lymphedema is a chronic disease involving the accumulation of protein-rich fluid in the interstitial space due to abnormal lymphatic circulation [1]. Lymphedema can be separated into primary and secondary types, and although it is induced by a variety of causes, it is most commonly caused by breast cancer itself or as a complication of breast cancer treatment [2]. The lymphedema that is caused by breast cancer itself or due to breast cancer treatments is called breast cancer-related lymphedema (BCRL), and its incidence is reported to be 6%-83%, indicating that different studies have found vastly different results [3]. BCRL is a serious complication that impairs the upper extremity functions and quality of life of breast cancer patients. The progression of BCRL is related to various risk factors including surgery, radiation therapy, chemotherapy, diagnostic time, pathological lymph node condition, infection, and weight gain [4,5,6]. Prevention by risk factor management is an important part of lymphedema treatment [7], and several studies have reported that the treatment effects, prognosis of BCRL, and the quality of life of breast cancer patients are greatly affected by the patients' awareness of BCRL and its risk factors [8,9,10]. Although there have been studies on BCRL-related awareness, risk factors, and education in other countries, no evaluation of the BCRL-related awareness level in Korean breast cancer patients has been conducted. Thus, the appropriateness of current BCRL-related education or of early detection of lymphedema cannot be determined. Therefore, this study was conducted in order to investigate the level of awareness of BCRL in breast cancer patients, and to provide the basic data needed to establish a proper education time and method.

Lymphedema following breast cancer surgery can cause a number of serious clinical or psychological problems. According to Tobin et al. [15], 46% of 50 lymphedema patients have a functional disability. Lymphedema is one of the most serious complications that can result from breast cancer treatment, which can clinically induce a limited range of motion and pain in the affected upper limb, weakness or tightness, and can cause secondary psychological problems such as anxiety, depression, sexual dysfunction, social avoidance, and aggravation of existing psychological illnesses [8,15,16,17,18]. There is currently no medical cure for lymphedema; therefore, it is important to prevent lymphedema by educating patients on the avoidance of risk factors and how to observe their own arms for early diagnosis and treatment [7,10,19]. Woods [8] conducted a survey of 40 breast cancer patients investigated with semi-structured interviews, Psychosocial Adjustment to Illness Scale, and limb volume measurement, and reported that increasing awareness has the benefit of maximum improvement and long-term control for patients with lymphedema. In addition, Sherman and Koelmeyer [11,12], reported that information delivery on lymphedema in a brochure format or via clinic staff plays an important role in minimizing the risk of lymphedema. Moreover, patients' higher awareness of lymphedema helps more effective early diagnosis and treatment of lymphedema. Fu et al. [13] also reported that education on lymphedema strengthens patients' self-management. Medical institutions in Korea are educating patients to be more aware of lymphedema, yet there have been no prior studies conducted on the patients' level of awareness or knowledge on the risk factors and treatments of lymphedema in Korea. Previous studies [10,11,12,13,14] conducted in other countries have the disadvantages of a small sample number of samples or survey over the phone. The present study increased the number of samples compared with the number of patients, and met with patients in person to survey them, in order to help to plan and conduct education on lymphedema for breast cancer patients in Korea.

Among the recruited breast cancer patients in the present study, barely more than half of the patients were aware of lymphedema as a disease, and only 30 patients (25.9%) received explanations about the possibility of lymphedema from the medical staff before surgery. The patients who were diagnosed with lymphedema showed a higher awareness regarding all of the items on the questionnaire. This means that prevention and management of lymphedema needs be carried out in the early stages and not conducted after exposure to various risk factors or after the diagnosis of lymphedema.

In addition, 20.69% of the patients who participated in the survey answered that lymphedema is a disease that does not require medical treatment, 82.75% answered that lymphedema is a curable disease, and notably, 21 out of the 30 patients (70%) who were diagnosed with lymphedema also answered that lymphedema is curable. Regarding the question asking whether they knew which medical department treats lymphedema, 51.73% of the patients either chose departments other than rehabilitation medicine or answered 'I'm not sure.'; only 19 out of the 30 patients who were diagnosed with lymphedema (63%) answered 'Rehabilitation Medicine'. According to the results above, the patients seemed not to have the proper information even after the diagnosis of lymphedema. In addition, for the questions regarding the risk factors of lymphedema, such as weight gain, hygiene, or aggravated lymphedema, patients showed a relatively lower level of awareness (55.6%) compared with that of the other items (70% on average) on the questionnaire.

Multiple regression analysis results show that the factors that affect this awareness are chemotherapy, lymphedema treatment, duration of illness, and age. In the case of those who underwent chemotherapy and lymphedema treatment with a long duration of illness, the patients may have had greater exposure to other patients or medical staff, and this may have had a positive effect on their awareness of lymphedema. In addition, considering that younger patients also exhibited a higher awareness, cognitive decline in the aging population may have affected the level of awareness of lymphedema. The above results suggest that the quality and timing of the current education on lymphedema are problematic.

Therefore, for proper management of lymphedema, education protocols considering age, duration of illness, and whether the patient has had chemotherapy need to be developed. In addition, although it did not significantly affect the level of awareness of lymphedema, the patients that were members of a breast cancer patient association and those who were diagnosed with lymphedema showed a difference in awareness level. More active education for breast cancer patients to approach their disease is necessary. In addition, continuous exposure to information on lymphedema can help to improve the patients' awareness level and approach towards lymphedema, even for those who have already been educated.

The limitations of the present study were the small number of subjects, and the fact that the difference in the level of awareness was not investigated before and after education on lymphedema, therefore the direct association between education and awareness level could not be proven. Moreover, the degree that education affects awareness could not be examined due to different learning abilities and educational backgrounds of the patients. In addition, the patients that were not diagnosed with lymphedema were not examined for the presence of lymphedema, and the investigation of the difference in the level of awareness of lymphedema and access to the diagnosis and treatment for lymphedema was not accurately conducted. Future studies need to recruit a greater number of subjects and work towards understanding the relationship between education and changes in the awareness level of patients.