MATERIALS AND METHODS
From January 2015 to December 2016, 23 cases of breast cancer single-stage thoracic metastatic lesions with clinical characteristics were treated using microwave ablation and minimally invasive open decompression treatment. Clinical characteristics included a Tokuhashi score greater than 8 points, pathological compression fractures, mechanical instability and radiological and/or clinical metastatic spinal cord compression. In our study, the patients’ clinical information, numerical rating scale (NRS) for pain assessment, Frankel Grade classification system score for spinal cord injury assessment, Karnofsky performance status (KPS) score and electronic medical records were collated and recorded in our center’s electronic medical record system.
All patients signed written informed consents before surgery, which was approved by the ethics committee of Affiliated Tumor Hospital of Guangxi Medical University. X-rays, computed tomography (CT) and magnetic resonance imaging (MRI) were used to evaluate the vertebral metastatic lesions. The scope of ablation and the type of surgical procedure were planned before surgery. The adjacent normal vertebrae were implanted with pedicle screws in patients undergoing the minimally invasive open decompression procedure. The pathological diagnosis of vertebral metastases was confirmed by pedicle screw biopsy. Guidance with fluoroscopy was used to allow precise control of the ablation antenna (2.45GHz, YiGao, ECO-100A1, Nanjing, China); thermometer placement was used to reduce the rate of complications and to avoid nerve damage during microwave ablation. The ablation antenna was placed in the center of the vertebral metastases through the pedicle (Figure 1). Thermometers were distributed in the vertebral anterior, vertebral center and vertebral posterior margin to protect the spinal cord and peripheral blood vessels in the thoracic spine. Ablation treatment was administered for 15–30 min while the vertebral center temperature was controlled between 50°C and 85°C and the surrounding tissue was maintained at a safe temperature of less than 43°C. Frozen saline was used to protect the spinal cord tissue to prevent excessive temperature. Metastatic tissue was removed and polymethyl-methacrylate cement was used to fill the vertebral metastases to prevent vertebral collapse.
(To view a larger version of Figure 1, click here.)
Data collection and outcome measures
Twenty-three patients underwent microwave ablation and minimally invasive open decompression. The patients underwent radiotherapy and chemotherapy after surgery. Patients were followed up for one month during the preoperative and postoperative period. All patients were included in the analysis. Because pain is the main complaint, we used pain improvement as a primary outcome measurement. NRS was recorded, and the Frankel Grade system was used to assess any impact on the nervous system. KPS was used to assess changes in the patients’ physical condition.
The data are expressed using mean±standard deviation. The before and after surgery parameters were identified using repeated-measures analysis of variance (ANOVA). The Mann–Whitney U test was used to compare changes in the cases where normal distribution could not be guaranteed. The chi-squared test was used to compare the categorical variables. A P-value of <0.05 was considered statistically significant. Data analysis was performed using SPSS version 22.0 (SPSS, Chicago, IL, USA).
Distribution of patient characteristic data
The study subjects consisted of 23 female patients, all of whom represented cases of single-stage thoracic metastasis from breast cancer. The mean age was 51.86±10.11 years (age range 38–68 years). Mean operation time was 177.21±60.04 minutes and the mean operative blood loss was 314.34±152.63 mL.
All 23 patients underwent surgical treatment and experienced pain relief. The level of pain during the preoperative and one-month postoperative period was assessed using NRS. The preoperative NRS score was 5.86±1.74 and the postoperative NRS score was 3.00±1.31. The differences in pain before and after surgery were statistically significant (Table 1).
A total of 23 patients presented with neurological symptoms (8 with Frankel Grade C, 12 with Frankel Grade D and 3 with Frankel Grade E). At the conclusion of the study one-month postoperative, all 23 patients had improved by one Frankel Grade and none had worsened (2 with Frankel Grade C, 8 with Frankel Grade D and 13 with Frankel Grade E). Nerve function recovery was rapid after the surgical treatment. Significant differences were observed in neurological symptom presentation before and after surgery (Table 1).
Functional outcome (KPS)
The KPS score was used to evaluate the functional outcome. At one-week post-surgery, the KPS score was significantly greater in 18 of the 23 patients, while 5 patients showed no deterioration in functional outcome. A comparison of the functional outcome results before and after surgery showed that the differences were statistically significant (Table 1).
There were no deaths 1 month after surgery. Two of the 23 patients had cerebrospinal fluid (CSF) leaks, 1 patient displayed delayed wound healing and 1 patient contracted a urinary infection. For all of the patients, the symptoms either disappeared completely or were significantly alleviated without complications using symptomatic treatment alone. No further surgical intervention was necessary.