In 2016, for the first time, Japan had over 1 million new incidents of cancer per year, which was more than the number of new births (1, 2). This might be explained by Japan’s super-aging society and the advances in cancer treatment (early diagnosis and treatment).

Recent advances in chemotherapy, molecular targeted therapy, immune checkpoint inhibitors, bone-modifying agents (BMA) such as zoledronic acid and denosumab, and radiotherapy have enabled multidisciplinary and comprehensive treatment, extending the lives of patients with cancer worldwide (3). Significant improvements in life expectancy have led to a new era of living with cancer with shortened hospital stays and increased outpatient treatments (4). However, although the prognosis of cancer patients improved, the incidence of metastatic cancer increased as well (5). Spinal metastases are the most frequent bone metastases (50%), and the prevalence of patients with spinal metastases increased in the past years (6). Spinal metastases have been identified in 36% of patients with malignant neoplasms (7). Spinal metastases can significantly reduce activities of daily living (ADL) and quality of life (QOL), compared with other types of bone metastases, as they are accompanied by severe pain and paralysis resulting from skeletal-related events (SREs). Declining ADL can be a significant burden on the life of the patient, leading to a shift in the management focus from curative treatment to life-prolonging palliative care.

The performance status (PS) is extensively utilized in oncology study and practice as a measure of ability to perform daily activities (8). PS 2, “ambulatory and capable of all self-care but unable to carry out any work activities; up and about more than 50% of waking hours,” represents the minimal requirement for chemotherapy to be proposed.

Declining PS can also lead to contraindications for chemotherapy and radiotherapy, resulting in shortened life expectancy. Therefore, the presence of spinal metastases is an important issue for patients, doctors, and society as it has a serious influence on the ADL, QOL, and life expectancy of patients. Furthermore, the population of patients with spinal metastasis is predicted to expand given the super-aged Japanese society and the improvement of imaging technology.

Thus, a paradigm shift in cancer care is currently taking place in Japan, where care is required not only to cure cancer, but also to preserve and improve the QOL of patients with cancer. A shift is being made towards accepting cancer to be a chronically ill condition and aiming to preserve and improve the ADL and QOL of patients with cancer. Consequently, the importance of maintaining ADL and improving the QOL of patients with spinal metastasis has increased, similar to the role of the spine surgeon in patient treatment.

A new era has arrived in which spine surgeons must use their specialist knowledge and skills to contribute as integral team members in cancer care. However, it has been shown that orthopedic surgeons in Japan are not having a proactive approach in the management of patients with bone metastases (1). Clinical inertia is a term that describes this lack of a proactive approach (9). Clinical inertia refers to the failure to start timely treatment and the failure to adapt the treatment in cases where evidence-based treatment targets are not met. In this review, we highlight three methods through which spine surgeons can overcome clinical inertia when treating spinal metastasis patients and become actively involved.

First, spine surgeons must be recognized for the locomotive syndrome in cancer patients (so-called “Cancer Locomo”) (1). The concept of Cancer Locomo, discussed in detail in Section 2, refers to musculoskeletal disorders in cancer patients and contributes to a more active involvement of spine surgeons in the management of spinal metastases. Ultimately, this will improve not only the QOL of patients with locomotor cancer, but also their prognosis.

In Section 3, we discuss the necessity of introducing a multidisciplinary approach. The momentum for the adoption of a multidisciplinary approach involving collaboration among multiple disciplines, such as radiology, orthopedics, oncology, palliative care, and rehabilitation for the prevention and treatment of SRE in patients with spinal metastases has been reported in various studies and clinical guidelines that are gaining momentum (10–16). With respect to spinal metastases, the importance of coordination between spine surgeons, radiologists, and oncologists is critical as failure to do so may delay treatment.

Third, spinal surgeons should consider the advancements in minimally invasive treatments to better manage spinal metastases. Advances in drug treatment, radiotherapy, and minimally invasive spine surgery (MISS) have expanded the management alternatives for patients with spinal metastases. Therefore, minimally invasive spine treatment (MIST) (17), a concept describing the minimally invasive management of spinal diseases and including conservative treatment, radiotherapy, and less invasive conventional surgery, has been proposed.

In Section 4, we describe the conventional surgeries and the MIST including high-precision radiotherapy. Knowledge of cancer locomo, multidisciplinary approaches, and MIST can help spinal surgeons to overcome clinical inertia in cancer treatment (Table 1). Moreover, these findings herald a new era in the management of spinal metastases for spine surgeons.

Since 2007, the Japanese Orthopedic Association has advocated “locomotive syndrome,” a condition in which motor functions are weakened caused by musculoskeletal disorders, and has promoted the “locomotive syndrome prevention” movement (18). The locomotive syndrome is characterized by impaired mobility due to muscle weakness and musculoskeletal disorders, whereas patients frequently requires nursing care (18). The need to manage musculoskeletal dysfunction in patients with cancer is increasing owing to an increase in the population of patients with cancer following advances in cancer treatment. Therefore, orthopedic surgeons are increasingly required to actively participate in the treatment of cancer, a term coined by the Japanese Orthopedic Association in 2018, building on the concept of locomotive syndrome (1).

Locomotive syndrome in patients with cancer defined as a reduced motor ability due to cancer-related motor dysfunction and was categorized by three categories:

This category includes locomotive issues that coexist with cancer, including osteoporosis, lumbar spinal canal stenosis, and osteoarthritis. These issues are sometimes inadvertently overlooked or undervalued in the orthopedic domain because of their primary focus on cancer.

Type 3, ostensibly tangential to cancer, is clinically important as such issues can be overlooked or underprioritized by orthopedic specialists with different oncological concerns (1). To address the overlooked or under-prioritized type 3 cancer-related motor impairments, the “Cancer Locomo” campaign advocates for a more inclusive role of the orthopedic surgeons in the cancer care. This campaign emphasizes the need for comprehensive locomotor management in patients with cancer, and ultimately aims to preserve patient autonomy and QOL, even for incurable or terminal cases.

Spine surgeons frequently address degenerative diseases, which often result in disengagements with oncological care and limited involvement in cancer treatment. This detachment may lead some spine surgeons to eschew involvement in cases involving patients with cancer, perceiving themselves as lacking expertise. Consequently, patients with cancer and comorbid locomotive dysfunction may miss the chance for adequate care because of their cancer diagnoses.

The principle of cancer rehabilitation institutionalized in Japan’s health insurance system in 2010 is dedicated to bolstering resilience and enhancing or sustaining functional capacity in patients with cancer (19). Conversely, campaigns addressing locomotive syndrome in cancer patients highlights the crucial role of maintaining and improving mobility through specialized management strategies. For example, while cancer rehabilitation might concentrate on adaptive training (such as wheelchair transfers) following pathological fractures, the Cancer Locomo approach advocates for aggressive surgical procedures such as internal fixation, total joint replacement, and spinal instrumentation to reinstate ambulatory capabilities. Collaborative synergy between cancer rehabilitation and Cancer Locomo can significantly enhance the ADL and QOL of patients with cancer. In general, limitations in daily activities caused by motor impairment also impact PS. Although poor PS in cancer treatment is generally a contraindication to chemotherapy and may lead to the discontinuation of cancer treatment, orthopedic surgeons have the possibility to correct the apparently poor PS due to motor impairment and expand the indications for cancer management further. In addition, pre-operative exercise may play a critical role in ensuring that patients achieve curative tumor resection; hence, leading to improved surgical outcomes and enhanced long-term survival (20). Therefore, managing spinal metastases from the Cancer Locomo perspective in cancer patients is critical not only for optimizing their QOL but also for improving their overall prognosis.

Insufficient recognition of the “Cancer Locomo” may result in clinical inertia among spinal surgeons when managing spinal metastases. A deeper understanding and more assertive intervention in Cancer Locomo can enhance not only the QOL of these patients but also their overall prognosis.

Recently, the management for spinal metastases has shifted owing to multimodal cancer therapy advancements, including advancements in chemotherapy, molecular targeted therapy, immune checkpoint inhibitors, BMA such as zoledronic acid and denosumab, and intensity-modulated radiotherapy, which can prevent spinal cord exposure (3). Hence, the aims of treatment for spinal metastases is changing from conventional palliative care to present QOL- or ADL-preserving care (1, 21).

SREs, such as bone metastases-related skeletal complications, defined as pathological fractures, spinal cord compression, necessity for radiation to the bone (due to painful or impending fracture), or surgery to the bone and are now recognized as factors that may affect the QOL and ADL of patients (22). The occurrence of SRE has been suggested to lead to worse prognosis, ADL disturbances or QOL deterioration (16, 23, 24). Thus, a primary objective in treating spinal metastases is to avoid pain, mechanical instability, and neurological deficits. As the SRE occurrence rate in patients with spinal metastasis was reported to be approximately 20% (23, 24), SRE prevention is gaining attention (25–28). Among SREs, symptomatic metastatic epidural spinal cord compression (MESCC) may result in nearly 20% of patients with spinal metastasis (23, 24). Watanabe et al. (29) and Helweg-Larsen et al. (30) described that the intensity of preoperative paralysis strongly influenced final walking ability. That is, once MESCC-induced severe spinal palsy occurs, the post-operative recovery and neurological prognosis do not improve. Therefore, screening and early diagnosis of spinal metastases and appropriate timing of surgery or radiation therapy are important for patients with cancer. Preventing subsequent complications such as MESCC and preserving ADL, including neurological function, may improve overall survival (31).

For cancer patients with bone metastasis, the significance of a multidisciplinary approach in the diagnosis, treatment, preservation, and ADL improvement has been recommended (1, 32, 33). In general, oncologists are constrained by their expertise in initial diagnosis and treatment of spinal metastases. However, multidisciplinary cancer board meetings on bone metastases are usually attended by primary cancer physicians, medical oncologists, orthopedic surgeons, spine surgeons, diagnostic radiologists, radiation oncologists, physiatrists, palliative care physicians, psycho-oncologists, physical therapists, occupational therapists, pharmacists, nurses, and medical social workers (32).

Preemptive treatment using a multidisciplinary approach includes prophylactic surgery, radiotherapy, and the administration of appropriate bone-modifying drugs to patients in need. Multidisciplinary approaches are reported to have a key role in patients with spinal metastases as they might lead to earlier recognition of a neurological deficit, initiation of radiological investigations, and treatment (33) Preservation of walking ability can be achieved by using radiotherapy for spinal cord metastases before walking function declines (19, 34), fractures and paralysis can be prevented through early detection of bone metastases via imaging surveillance even in the absence of subjective symptoms (20, 35), and paralysis as well as surgery can be prevented by timely interventions of a liaison team before SREs occur (21, 26). Maintaining the ability to walk at the terminal stage (30 days prior to death) (21), reduced costs and hospitalization (10–16), and improvement of the rate and severity of neurological impairment subsequent to local treatment (26). These ultimately improvement the overall survival (26, 32, 36).

Furthermore, a multidisciplinary approach is expected to contribute to the understanding and awareness of cancer locomo. In Japan, although the benefits of preemptive medicine with a multidisciplinary approach for patients with spinal metastases have become apparent, such multidisciplinary approaches are not common even in cancer hospitals (34). This might be explained by clinical inertia from spinal surgeons that are involved in the management of spinal metastases. Preemptive treatment using a multidisciplinary approach improves not only the QOL of patients with cancer locomo but also their life expectancy. Therefore, nationwide environmental improvements are required.

Surgical interventions for metastatic spinal tumors include radical (curative), pre-emptive prophylactic, and palliative interventions, with treatment options based on various decision-making systems. Surgical indications for metastatic spinal tumors include refractory pain, progressive palsy, and/or the development of bladder or bowel disturbances due to mechanical instability of the spinal structures and/or spinal cord/cauda equina/nerve root compression due to metastatic tumor invasion. Surgical interventions should be performed under tolerable general conditions rather than considering only life expectancy, which should longer than 3–6 months.

For patients with spinal metastases and a favorable PS, the absence of metastases to major organs, and tumors confined to the vertebral body, radical surgery including total en-bloc spondylectomy (TES), for complete removal of the tumor is preferred (35, 37). Based on tumor localization, less invasive radical surgeries including sagittal en-bloc spondylectomy and contralateral osteotomy of the pedicle and posterolateral elements for en-bloc resection (COPPER) have also been reported (38–40).

However, the number of patients who can be treated with radical surgery is limited due to the invasive and technical demands of the intervention. Recently, long-term local control has become possible by combining palliative surgery with radiotherapy and drug therapy (anticancer drugs and bone-modifying agents). Preemptive prophylactic surgeries and palliative interventions such as posterior fixation and decompression (41), separation surgery (42) and balloon kyphoplasty (BKP), including percutaneous vertebroplasty (PVP) (43), have been reported. Minimally invasive spine stabilization surgery (MISt) using percutaneous pedicle screw (PPS) fixation, which has been conducted commonly in Japan since 2005, applies to cancer patients in poor general condition (27). MISt is a minimally invasive fixation method that involves temporal stabilization of the spine using a PPS, which alleviates pain, promotes early ADL improvement, and prevents pathological fractures.

Approaches that render the management of spinal metastases less invasive, including radiotherapy, BKP, and MISt, are collectively referred to as MIST (17). MIST can provide an improvement in prognosis for patients ineligible for conventional invasive surgery (17, 27). MIST have expanded the indications for surgery and become essential for patients with cancer. If spinal surgeons lack the knowledge and interest in MIST approaches for spinal metastases, this could be considered clinical inertia. This section outlines decision-making systems and the management of metastatic spinal tumors.

The ability to walk is important for extending the duration of life with cancer and for enabling cancer patients to live their own independent lives, continue to work, and continue cancer treatment until the end of their lives. Spinal metastases have a significantly impact on walking ability and spinal surgeons must be actively involved in the therapeutic process. However, orthopedic and spinal surgeons in Japan tend to avoid involvement with patients with cancer. Spine surgeons can overcome clinical inertia in cancer treatment by improving their knowledge of cancer locomotion, non-surgical treatment, multidisciplinary approaches such as cancer boards and clinical conferences, and various surgical procedures, including radical resection and MIST. Preserving the QOL and ALD of patients with cancer should be the mission of orthopedic and spinal surgeons.

TM: Conceptualization, Data curation, Funding acquisition, Investigation, Methodology, Project administration, Writing – original draft, Writing – review & editing. YuT: Conceptualization, Data curation, Investigation, Visualization, Writing – original draft. MH: Conceptualization, Supervision, Writing – original draft, Writing – review & editing. PP: Conceptualization, Data curation, Formal analysis, Writing – original draft. KW: Conceptualization, Investigation, Validation, Writing – original draft, Writing – review & editing. KK: Data curation, Formal analysis, Investigation, Writing – original draft. MT: Supervision, Validation, Writing – review & editing. HH: Conceptualization, Methodology, Supervision, Validation, Writing – review & editing. YK: Conceptualization, Data curation, Formal analysis, Methodology, Supervision, Writing – original draft, Writing – review & editing. YaT: Conceptualization, Data curation, Investigation, Writing – original draft. SN: Project administration, Supervision, Validation, Writing – review & editing. KN: Formal analysis, Project administration, Supervision, Validation, Writing – review & editing. HK: Investigation, Supervision, Validation, Writing – review & editing. YM: Methodology, Project administration, Supervision, Validation, Writing – review & editing. KO: Data curation, Formal analysis, Methodology, Project administration, Supervision, Validation, Writing – review & editing. MM: Methodology, Project administration, Supervision, Validation, Writing – review & editing. TN: Data curation, Methodology, Supervision, Validation, Writing – review & editing.