This study was approved by the Hospital Ethics Committee (GYX2020-002). The study reporting adheres to the law of China and the 2008 version of the Declaration of Helsinki. Written informed consent forms were signed by all participants or their legally authorized guardians regarding the diagnosis, pathology, and publication of the patients’ personal information in article form. A total of 100 patients with upper extremity lymphedema after breast cancer surgical intervention who were admitted to the lymphedema clinic of our hospital from March 2019 to December 2019 were selected by a convenience sampling method. Patients who met the inclusion and exclusion criteria and signed the informed consent form were directly included as research subjects. All the patients were then equally divided into the experimental group and the control group with 50 patients in each group. The inclusion criteria were: (1) Diagnosis of subcutaneous soft tissue lymphedema of the upper extremity by lymphography and/or color ultrasound; (2) no prior CDT; (3) age ≥ 18 years; (4) education level above primary school level with certain reading and writing abilities; and (5) agreement to participate in the study and provision of informed written consent. Patients were excluded according to the following criteria: (1) Past or current history of a psychiatric disorder; (2) already identified recurrence, distant metastasis or metastatic cancer; (3) serious systemic diseases related to the heart, lung, liver and kidney; (4) past history of severe complications such as severe systemic infection, anemia and cachexia; (5) past history of thrombus and tumor emboli; (6) local infections such as ulcers and bleeding tendencies; or (7) inability to continue the treatment due to physical reasons during the treatment process. The demographic and clinical data of the patients are presented in Table 1.

The patients were assessed and treated at the ambulatory clinic of Sun Yat-sen University Cancer Center by a senior nurse with an internationally recognized lymphedema therapy certification, who is also called a lymphedema therapist. According to the Vodder method, the patient was completely relaxed. The therapist used the large and small thenar muscles of the palm or the closed index finger, middle finger and ring finger to touch the nearby superficial lymph nodes with moderate strength to stimulate superficial lymph nodes, to dredge the lymphatic channels and accelerate lymphatic circulation. All patients completed one course (20 treatments over 28 days) of the six-step treatment. Skin care was provided by the lymphedema therapist for approximately 10 min. Upon completion of manual lymphatic drainage, the patients were treated with air pressure wave therapy for 15 min and then with bandages. This was followed by functional exercises supervised by a lymphedema therapist. The entire treatment process took approximately 1.5 h per day.

The control group was given conventional CDT (international standard four-step method). The steps were as follows:

Skin care: The objectives of the skin care component were to clean the skin and address any skin-related complications. Firstly, the patients were instructed to wash and dry their skin using pH-neutral soap. Any wrinkled skin was kept clean and dry. A further goal was to protect the skin from cuts, abrasions, and bites (especially sensitive skin). Finally, complications such as skin keratosis, fungal infection, lymphatic leakage, ulcers and lymphangitis were treated.

Manual lymphatic drainage: The therapist touched the affected side of the limbs from the distal end to the proximal end of the heart along the superficial lymphatic vessels, with circular propulsion, rotary propulsion, and spoon-shaped propulsion. The drainage procedure was started at the beginning of the chest wound after surgery, i.e., wound scar after mastectomy and breast conserving operation, and then moved to the upper side of the chest (drainage to the contralateral axillary or ipsilateral supraclavicular lymph nodes), the lower side of the chest wound (drainage to the ipsilateral inguinal lymph nodes), the medial lymph nodes of the upper arm (drainage to the supraclavicular lymph nodes), the medial lymph nodes of the upper arm (drainage to the ipsilateral inguinal lymph nodes through the dorsal armpit or dorsal side of the body), the lymph nodes on the back of the hand, the palm and forearm (drainage to the cubital fossa lymph nodes) and, finally, the lateral upper arm. The touching technique needed to be gentle to avoid local skin reddening[12-14]; a pressure of 25-30 mmHg was applied.

Pressure dressing of foam granule bandage: The retaining bandage was wound around the finger joint and hand. Cotton bandages were run from the hand to shoulder. The foam pellet bandage started at the hand and was wrapped under the shoulder with a 50% overlap. The short stretch bandage started at the back of the hand and was then wrapped under the shoulder with 50% overlap. The pressure gradient was gradually decreased from the distal to the proximal end. During the dressing, the socket was kept in the functional position. The high elastic bandage was applied from the back of the hand. The pressure was drawn into a square pattern according to each pattern set on the surface of the bandage and wound under the shoulder with 50% overlap. The elastic bandage layer should be tightly wrapped to accommodate the finger. The pressure was maintained appropriately, as making the bandage too tight could affect the blood circulation of the affected limb and leaving it too loose would not achieve the therapeutic effect[15].

Functional exercises: After bandaging, the patients were instructed to partake in functional exercise, and each joint was moved according to the six-step health exercise[15]. During exercising, the muscles expand and contract, and the bandage resisted muscle expansion and exerted force on the intermittent pressure of deep tissue. When resting, the muscle relaxes, and the bandage’s resilience acts on the tissue to produce persistent pressure, thereby promoting the flow of lymph. This protocol is consistent with the guidelines for preventing upper limb lymphedema proposed by the National Lymphedema Network in 2003[16]. The patients were advised to practice self-care to prevent lymphedema by avoiding the following things: infusion into the affected limb (to avoid increasing the circulation load of the affected limb); measuring blood pressure; wearing tight jewelry; performing any swinging, throwing, pulling, or pressing movements; lifting weights; damaging the skin; exposing the affected limb to excessive heat or cold; and wearing elastic cuffs for extended periods of time. In addition, during airplane flights, the cabin pressure is less than the atmospheric pressure on the ground. As the plane rises from sea level to an altitude of 6000-8000 feet, the pressure in the cabin decreases further. Reduced cabin pressure leads to changes in tissue pressure that may worsen lymphedema. Therefore, when flying, patients should wear elastic sleeves and perform unarmed lymphatic drainage.

The experimental group received six steps of CDT. The additional two steps were as follows:

Treatment of scar tissue: Firstly, the nurse opened the lymphatic pathways as mentioned earlier. Then, the therapist touched the superficial lymph nodes with their index finger, middle finger, and ring finger, applying a static rolling motion with moderate intensity. The nodes were touched in the following order: supraclavicular lymph nodes, cervical lymph nodes, anterior and posterior auricular lymph nodes, sternal lymph nodes, axillary nodes, elbow lymph nodes, thoracic lymph nodes, dorsal lymph nodes and inguinal lymph nodes[12]. Then the therapist used the finger pulp of both hands to relieve the scar tissue, loosen the connective tissue, and reduce the scar contraction, which further led to reductions in lymphatic compression and backflow obstruction and increased the range of motion of the shoulder joint.

Foam granule bandage combined with an air wave pressure therapy instrument: A foam granule bandage combined with a POWER-Q6000 air wave pressure therapy instrument was used for treatment. The instrument is produced in Korea, and includes two parts: an electric air pressure pump and an inflatable sleeve. The sleeve generally has six cavities, and the nurse works one by one after inflating the sleeve along the long axis of the limb to the root of the limb press. The patient was placed in the supine position, and then a foam pellet bandage was wrapped around the back of the hand with 50% overlap until it reached below the shoulder. Then the whole affected limb was wrapped with the upper limb cuff of the air wave pressure therapy instrument containing 6 air sacs. The nurse then pressed the area from the distal end to the proximal end of the full circle with pneumatic pressure in an orderly manner. The pressure was increased gradually from 25 to 30 mmHg. The maximum pressure was kept at 45 mmHg, once a day, for 15 min. At the same time, according to the observation and analysis of subjective and objective symptoms, the subjective symptoms were numbness and pain of the affected limbs and fingers, and the objective symptoms were dark purple and cold fingers. If the patient felt uncomfortable with the affected limb or had dark purple fingers on the affected side, the treatment was suspended immediately[17].

Bioelectrical impedance analysis (BIA): Bioelectrical impedance analysis (BIA) was used to measure the change in body water content before and after treatment. Electrical impedance is one of the most important physical characteristics of the human body. The body bioelectrical impedance (50 HKz) and extracellular moisture ratio of patients in both groups were compared from before the start of the session to after the 20th session. A lower bioelectrical impedance indicated a higher extracellular moisture ratio, indicating more serious edema[9]. An InBody S10 body composition monitor (BCM) was used to measure the trunk bioelectrical impedance and extracellular water ratio at 50 Hz before treatment (the first time) and after treatment (the 20^th time).

The Lymphedema and Breast Cancer Questionnaire (LBCQ) 17, which includes 19 lymphedema-related symptoms, including numbness, tightness, stiffness, pain and heaviness, etc. was used to evaluate the occurrence of lymphedema-related symptoms in patients at the present time, in the past 1 mo and in the past 1 year. The patients answered "1" or "0". The internal consistency coefficient of the questionnaire was 0.785, and the retest reliability was 0.98018. This study was analyzed and discussed by members of the research group according to the conditions of patients in this study. Six items of tightness, pain, numbness, stiffness, swelling, and limited shoulder movement were selected and evaluated by lymphedema specialist nurses before and after each course of treatment, i.e., after the 20^th cycle.

SPSS version 25.0 (IBM Corporation, Armonk, NY, United States) was used for statistical analysis. The Mann-Whitney U test, χ² test, and Fisher exact test were used to analyze the differences between the two groups.

In both groups, the body water content was compared before treatment and after the 20^th session. The results of the study showed that the body water content was significantly improved after treatment in the experimental group as compared with the control group (P < 0.05, Table 2).

The subjective symptoms were compared between the experimental group and the control group before and after treatment. The results of the study found that the subjective symptoms were improved in both groups. After treatment, the body tension and swelling were more effectively reduced in the experimental group compared with the control group (P < 0.001; Table 3).

In this study, the sample size was small; the collection time and follow-up time were short; and the long-term effect was unclear. In addition, it was controversial whether climate was a factor affecting the therapeutic effect for lymphedema. In the future, multi-center studies must be carried out with an increased sample size, a comparison of lymphedema in different stages, extension of the follow-up time, use of additional relevant scales for quality of life and treatment compliance, and use of better observation indicators, so that more powerful clinical evidence can be obtained.

Patients with lymphedema following breast cancer surgery are likely to suffer from an abnormal appearance of the limb, susceptibility to fatigue, repeated limb infections, and limb dysfunction, which further seriously affects their quality of life. Active and effective treatment for upper limb lymphedema is very important for improving the health and quality of life of patients after breast cancer treatment. Complex decongestive therapy (CDT) is currently recommended as the standard treatment for lymphedema. CDT is a four-step detumescence therapy that can effectively treat upper limb lymphedema after breast cancer surgery, and is considered non-invasive, painless and without side effects. CDT typically involves manual lymphatic drainage, elastic bandage compression, limb function exercises, and personalized skin care. However, for the purposes of reducing scar formation and preventing axillary reticulum syndrome, this study added two steps to create a six-step comprehensive deswelling therapy combined with the use of a foam type granule bandage, which was applied in the treatment of upper extremity lymphedema pressure.

At present, there are few studies on the treatment of lymphedema after breast cancer surgery in China, and most of the relevant studies focus on the efficacy of single or composite methods. This study is based on the international standard four-step CDT with improvements, and the treatment mode is standardized and reasonable. The six-step CDT method was found to effectively treat upper limb lymphedema after breast cancer surgery, without trauma, pain, or side effects. At the same time, this study found for the first time that in the early stage of CDT, edema of the affected limb was temporarily aggravated, and the clinical nursing staff need to provide targeted education for patients in order to improve treatment compliance.

The six-step CDT developed in this study effectively alleviated upper limb lymphedema after breast cancer surgery, and the subjective symptoms of patients were reduced or disappeared. Moreover, patients’ self-care ability was improved, which will lead to improvements in the quality of life and treatment compliance among patients. Lymphedema is a chronic and long-term process that requires patients to adhere to the treatment for the curative effect to be stabilized. However, in real life, patients often cannot adhere to the treatment for a long period, and the symptoms of lymphedema may return or be aggravated. At the same time, treatment fatigue is possible, and then treatment compliance gradually decreases. Therefore, good treatment methods and obvious treatment effects can further improve patient compliance. Lymphedema therapists have further investigated methods to improve treatment compliance and the follow-up rate of patients with lymphedema.

No six-step approaches to CDT for the treatment of upper limb lymphedema pressure have been reported in the literature, and most related studies have focused on the treatment effect of each individual method. This study adopted six-step CDT for the pressure treatment of upper limb lymphedema, which was found to effectively treat upper limb lymphedema and improve the quality of life of patients, which is worthy of discussion and further research. The results of this study provide a basis for the prevention and treatment of lymphedema in a specialist nursing clinic, and provide a talent basis for the study class of lymphedema specialist nurses, which can be used as a reference for future generations.

The newly introduced six-step CDT can improve the symptoms of upper limb lymphedema after breast cancer surgery and takes full advantage of the ability of nurses to treat lymphedema. Thus, it is a practice that should be referenced and promoted. Lymphedema treatment is a long process, and our future research will expand upon this study by increasing the sample size, extending the follow-up time, and observing the curative effect of therapy, in order to develop better treatment methods for lymphedema.

This study put forward a new theory regarding scar care and the effect of a foam rolled bandage combined with the use of an air pressure wave therapeutic instrument. The new method included two new steps in addition to those of the international standard four-step treatment.

In the future, multi-center studies are needed that include a larger sample size, compare lymphedema at different stages over a longer follow-up time, apply additional relevant scales for quality of life and treatment compliance, and improve the observation indicators, so that more powerful clinical evidence can be obtained.