In this study, the lung, breast, renal, and prostate cancers were the predominant primary sites, as observed in previous reports, including cases where the primary site was unknown at the time of treatment initiation. This trend was similar in the early and late groups, and patients with a history of these cancers should be wary about spinal metastasis.
In this study, the time between the previous doctor’s visit and a visit to our hospital decreased in the preceding 5 years, and the percentage of non-ambulatory patients at the time of visit to our hospital decreased. This may be due to the increasing momentum of multidisciplinary treatment in recent years, and the requirement for early intervention for spinal metastases has been recognized by the primary doctors. Nonetheless, the effect of surgical treatment on patients who developed paralysis was limited in both groups, and more than 50% of patients were unable to regain ambulation. Patchell et al.  reported that in a randomized controlled trial of 101 patients with spinal metastases and neurological symptoms, the surgical results were significantly superior to those who underwent exclusive radiotherapy. Rades et al.  performed a matched-pair analysis of 108 patients and reported that the results of combined surgery and exclusive radiotherapy were comparable. The radiosensitivity of carcinoma varies, and the mode of spinal cord compression, patient’s general condition, and prognosis for life are also extremely variable; therefore, a decision regarding the treatment strategy often depends on the individual case. At our hospital, patients with spinal cord symptoms were treated with posterior decompression and fusion in addition to radiotherapy, provided their general condition allowed for these treatments. MIST, using percutaneous pedicle screws [4, 5] and percutaneous vertebroplasty [13, 14], was recently introduced. In a systematic review by Mendel et al., percutaneous vertebroplasty was found to be effective in treating metastatic spinal tumors .
These surgical interventions are based on the idea that, as a merit, they can indirectly prolong life by improving the activities of daily living (ADL) through surgery and increasing the probability of receiving postoperative adjuvant therapy. However, minimally invasive procedures are particularly beneficial to patients who are not paralyzed and do not require decompression. In cases where spinal cord compression is strong and paralysis appears, posterior decompression and resection of the tumor must be performed in combination, considering the possibility of postoperative paralysis flaring up or worsening due to tumor growth. Grade 3 on the epidural spinal cord compression scale  indicates the requirement for posterior decompression or tumor resection in principle . In recent years, TES, a radical surgery for spinal metastases, has also been reported to improve the local control of metastases and prognosis of life in certain carcinomas, depending on the primary tumor stage [18, 19]. However, this treatment is not indicated when the tumor is advanced and has multiple metastases.
Radiation therapy should be initiated as soon as the diagnosis of metastatic spinal tumors is confirmed. The National Institute for Health and Clinical Excellence guidelines recommend that radiotherapy for spinal metastases should be initiated within 24 h after diagnosis .
On this premise, it is clear that surgical or radiation treatment should be performed as early as possible before the appearance of lower paralysis symptoms.
In this study, the referral time from the primary doctor consultation to our hospital was shortened; however, it took a relatively long time from the onset of pain to the primary doctor visit. In particular, in patients with pain as the only symptom, it took 26.5 and 19.8 days for the patients in early and late groups to consult the primary doctor, respectively. Even in cases where lower paralysis appeared, it did not occur suddenly; in many cases, pain occurred in the spinal metastases as a prodromal symptom a few days before the onset of paralysis. When paralysis occurs due to spinal metastasis, ADL and QOL decrease significantly. If the performance status is reduced due to paralysis, aggressive treatment, such as chemotherapy, cannot be performed, rendering it difficult to improve the prognosis. Even though there are several treatment options, early detection remains considerably crucial. In this study, molecular-targeted therapy was administered more frequently in the late group, which may have contributed to the recovery of postoperative gait function. Advanced medical treatments, such as molecular-targeted therapy and immunotherapy, have significantly developed in recent years, especially in lung and breast cancers [21, 22], and may expand the indications for surgery for patients with spinal metastases in future. Early detection of spinal metastasis and timely intervention are therefore necessary. In light of the above, raising awareness of spinal metastases in patients who experience pain that appears without a trigger and persists for several days and encouraging these patients to seek medical attention are potentially effective.
In this study, we investigated the changes in the patient status and treatment of metastatic spinal tumors over the past 10 years. This study has certain limitations. We did not include cases treated with advanced radiation therapy, such as heavy particle therapy, stereotactic body radiation therapy, and intraoperative radiation therapy. Although the usefulness of these therapies for metastatic spinal cord tumors has been reported in recent years [23, 24], reports of their benefit to patients with respect to gait function are scanty, and future studies are warranted. In addition, it was a retrospective study, the primary carcinoma was not analyzed in detail, and the long-term results of the patients were not followed. Few studies have investigated the evolution of treatment and patient status at the initiation of treatment for metastatic spine tumors, which are subjected to ever-changing treatment strategies. In recent years, patients with metastatic spine tumors have been promptly referred by their primary doctors under a favorable medical cooperation system. However, the effectiveness of the treatment of patients with lower paralysis remains limited, and it is desirable to create a system for earlier detection.