DISCUSSION

The treatment of cancer with spinal metastasis is palliative. The main purpose of the treatment is to relieve pain, alleviate symptoms of nerve compression and reduce the instability of the vertebral body. This study assessed the efficacy of treating breast cancer patients with thoracic spinal metastases using microwave ablation and minimally invasive open decompression therapy. The majority of the patients reported pain relief following surgery. Neurological function improved in 56.5% of the patients. According to the KPS metric, 78.3% of the patients showed improved function. Overall, the postoperative complications were less for the patients in this study than they are for patients that undergo a traditional open surgical intervention. The study results showed that microwave ablation and minimally invasive open decompression of thoracic metastases from breast cancer significantly enhanced the patients’ quality of life, reduced patient pain and improved patient recovery.

Previous studies have reported that 80% of patients with metastatic cancer of the spine are often troubled by pain.3 Pain is primarily caused by the local inflammatory response due to tumor enlargement, periosteal tension and expansion of the epidural venous plexus. Radicular pain is often due to compression of nerve tissue from the underlying nerve roots. Moreover, pain can be directly related to the axial instability caused by bone destruction. The pain caused by spinal metastasis is often caused by a combination of one or more of these factors.4 Microwave ablation destroys sensory nerve fibers, narrows the lesion and reduces the nerve stimulating factors produced by the destruction of tumor cells, resulting in pain relief.

Spinal cord dysfunction is associated with spinal cord metastasis. Surgical decompression is still the main treatment option for neuropathy because it quickly and effectively restores nerve function.11,12 In general, spinal decompression is achieved by posterior decompression laminectomy because it can ease the compression of the spinal cord and improve neurological function. However, most spine metastases involve the anterior and middle column of the spine.13,14 With the development of spinal surgery, metastatic lesions require more aggressive methods metastatic lesions require methods of total decompression, such as circumferential compression or combined approaches (involving anterior and posterior decompression). These techniques are associated with massive bleeding events, which can affect a patient’s quality of life and delay the administration of adjuvant therapy. Microwave ablation was developed and introduced for this condition in order to overcome this surgical risk. Microwave ablation is more effective in the ablation of bone tissue, especially in sclerotic bone lesions. The ablation process is less affected by the surrounding soft tissue, and it is more penetrating and effective than other methods. The application of microwave ablation in surgery destroys most of the tumor cells, delays local recurrence and reduces tumor-related bone destruction. However, when using this procedure, it is essential to control the microwave ablation safety boundaries and protect the spinal cord nerve tissue. Although the tumor tissue is not completely ablated, the patient can still benefit from treatment, particularly if they have aggressive malignant tumors. The risk of spinal cord injury is effectively avoided by proper temperature probe placement under open conditions. Radicular compression and spinal cord dysfunction are reduced or restored using circumferential decompression. If the nerve root of the thoracic spine is invaded by the lesion, the pain can be prevented by sacrificing the nerve root. Therefore, microwave ablation is effective in the treatment of neuropathic pain and the recovery of spinal cord function.


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After surgical decompression of the middle and posterior columns of the spine, the nerve root is compressed, which can result in the loss of integrity of the vertebral body structure.15 Therefore, reconstruction of vertebral integrity is critically important. The pedicle screw stabilization system provides strong fixation when utilized through a posterior approach. Vertebral resection is ideal for posterior fixation. However, this technique is associated with muscle dissection, detachment and devascularization, leading to major surgical-related complications, including bleeding, pain, infection and prolonged immobilization and recovery. Subsequently, wound healing is prolonged or inhibited, and further adjuvant radiotherapy and chemotherapeutic treatments are delayed. This can make it seem as if surgical efforts to control the tumor are ineffective. Thus, minimally invasive surgical approaches are needed.

Over the past several years, minimally invasive open decompression has been rapidly developed.16 The minimally invasive open decompression technique is mainly used to treat spinal cord compression, but there is no direct impact on spinal metastatic tumors. Additional microwave ablation therapy is required to achieve partial tumor control. The purpose of the procedure is not to entirely resect the tumor; it is only used to partially resect the tumor. Microwave ablation and circumferential decompression treatment creates sufficient space to allow polymethyl-methacrylate cement injection, facilitating little to no resistance, which can reduce the risk of bone cement leakage. Pain receptors are also simultaneously destroyed by the procedure. Injection of the polymethyl-methacrylate cement can strengthen the vertebral body to prevent pathological fractures and to establish the spinal cord barrier to prevent metastases.

In this relatively small study, no perioperative mortality was reported. The postoperative complications included cerebrospinal fluid (CSF) leaks, delayed wound healing and urinary tract infection. Symptomatic treatment resolved all of these complications. All the patients recovered postoperatively.

Limitations

This study has some limitations. Firstly, it is a retrospective observation with a relatively small sample size. Secondly, the follow-up time was relatively short. Thus, a randomized controlled trial with a longer follow-up period and a larger sample size is warranted to explore the effects of microwave ablation combined with minimally invasive open decompression for breast cancer patients with thoracic metastasis.

CONCLUSIONS

The study results suggest that the approach presented in this paper represents an improvement in the current surgical treatment procedures for thoracic metastases from breast cancer. The goals of spinal metastases tumor treatment include debulking the lesion, neuronal decompression and mechanical stabilization, all of which can be completed with microwave ablation combined with minimally invasive open decompression. To summarize, the application of microwave ablation combined with minimally invasive open decompression may be an effective alternative to the established treatment methods for breast cancer patients with thoracic metastasis.

Acknowledgments

The relevant human materials have been reviewed and approved by the ethics committee of Affiliated Tumor Hospital of Guangxi Medical University, and the study is deemed to meet the medical ethical requirements. We wish to thank the patients and families involved in this study for providing written informed consent for publication of the accompanying images. This work was supported by the Guangxi self-funded research project [grant number Z20170425 and Z20170428].

Disclosure

The authors report no conflicts of interest in this work.


Bin Liu,1,* Zhenchao Yuan,1,* Chang yuan Wei2

1Department of Bone and Soft Tissue Neurosurgery, 2Department of Breast Tumor Surgery, Affiliated Tumor Hospital of Guangxi Medical University, Nanning, China

*These authors contributed equally to this work.


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Source: Cancer Management and Research.

Originally published May 31, 2018.