Epidemiological studies have reported that MSCC could be the initial presentation of malignancy up to 20%,3–5 and it can occur in any cancer type.10–12 Regardless of whether the site of the primary cancer is known or not, surgery does play a role in spinal metastases management because MSCC is an oncological emergency that necessitates immediate surgical intervention. According to a recent review, an integrated multidisciplinary approach is needed for the management of spinal metastases due to its complexity.2 Before selecting an appropriate surgical approach, it is crucial to have an initial assessment of patient performance status, systemic burden of disease, and systemic treatment options. If the patient has very poor performance status, extensive systemic disease, or lack of available systemic treatment, these factors might preclude the possibility of better neurological recovery after the operation.
Two prognostic scoring systems, Tomita score and revised Tokuhashi score, are used to guide the management of spinal metastases.13–14 However, they are not practical in the setting of MSCC due to the lack of time for extensive surveys. The treating surgeon first encounters the issue as to whether the patient should undergo surgery. If surgery is indicated, the treating surgeon has to decide which surgical approach is appropriate.
There are a few articles that have addressed the issue. The first report of a surgical series concerning patients with an unknown source of spinal metastases found that select patients could benefit from aggressive surgical intervention.6 However, the extent of resection had no effect on survival or local recurrence. The population in this study was heterogeneous because they included patients who had a prior diagnosis of malignancy and subsequent treatment. In addition, this study included all the patients with spinal metastases, which might be different from MSCC. Two other studies published in the United Kingdom and Sweden analyzed patients presenting acutely with MSCC due to an unknown primary cancer.7–8 It has been reported that most patients underwent posterior fixation and stabilization, and they had similar complication rates, hospitalization durations, and neurological outcomes as those patients with a known primary. Postoperative survival was dependent on the type of primary tumor, and patients with cancers of unknown primary had the worst prognosis. This finding supported the recommendation that the surgery was safe and should be done as soon as possible. However, both studies do not compare the surgical outcome of different surgical approaches. The latest article published in China compared the surgical outcomes of different modalities in patients with spinal metastasis from cancer of unknown primary.9 The article described a better neurological recovery and quality of life for the patient after surgery. Within that group, the patients could benefit from more aggressive approaches. Of note, this study does investigate the surgical outcomes of patients with cancer of unknown primary whose primary site of cancer could not be found even after a detailed survey. Overall, there is limited literature to address the issue about the outcomes of different surgical approaches in patients with MSCC as first the manifestation of malignancy.
Our anatomical distribution of spinal metastasis was in agreement with previous studies with most cases being in the thoracic spine followed by lumbar and cervical spine. The initial Karnofsky performance and Frankel scales in both groups were better than those in most of the previous reports. This finding might be the result of rapid medical accessibility and early referral from the treating physician due to awareness of the spinal emergency. Both Karnofsky performance and Frankel scales in each group improved three months after the operation, a finding that agreed with those of previous studies in which surgery was warranted and could maintain and improve ambulatory function in patients with spinal metastasis or MSCC as the first manifestation of malignancy. We found only three patients in our cohort who had neurological deterioration after the operation. All of them were in the palliative group, one with debilitating back pain refractory to medication, another with post-operative stroke with hemiplegia, and the other with Brown-Séquard syndrome. To compare the outcomes of different surgical approaches in these patients, we analyzed survival curves from the end of the latest follow-up. There was a significant difference in PFS between the two groups with longer survival in the debulking group. However, there was no significant difference in OS between groups. The analysis concerning neurological adverse events at one and three months after the surgery revealed that the outcome was not related to variables other than surgery, which indicated that different surgical modalities accounted for different surgical outcomes. Of note, the initial Tomita score in the debulking group was higher than that in the palliative group. It is counterintuitive to the prognostic model based on the Tomita score because the present study showed that surgical outcomes were better in the debulking group. Thus, a more aggressive approach was warranted in managing patients with metastatic spinal cord compression as the first manifestation of malignancy.
Cancers of unknown primary are defined as histologically proven cancers whose primary sites cannot be identified after extensive investigation.15–16 Prognoses for these patients are not as optimistic as those with known primary cancer because of their aggressiveness, early dissemination, and unpredictable nature.17–18 Despite systemic treatment, the median OS of the patients with cancers of unknown primary is about 6 to 12 months.6–7, 18 Our study demonstrated that these patients could benefit from debulking surgery if the cancer type was unknown when the surgeon made the decision to perform surgery. However, the importance of a thorough evaluation in order to identify the primary tumor cannot be overemphasized. Those patients with known primary cancer can have adequate systemic therapy that significantly improves OS over those with cancers of unknown primary. The outcome of improving both Karnofsky performance and Frankel scale scores after the operation means that these patients have the opportunity to rapidly proceed to systemic therapy and thus, have longer survival. In addition, the median time from a patient’s arrival at our hospital to the operating room is about 12 hours in each group (minimum six hours, maximum 120 hours), which is much shorter than in other countries.7,19 One study published in the United Kingdom reported that earlier surgery could provide better neurological recovery19; however, the effect was not significant, and most of the patients underwent surgery 48 hours after the arrival. Further studies are needed to clarify whether earlier surgery could provide more neurological recoveries and longer survival. In summary, our findings highlight the importance of a more aggressive surgical approach in managing patients with metastatic spinal cord compression as the first manifestation of malignancy.
The present study has several limitations. First, this was a retrospective study. The patients were not randomized, and the surgical approaches were chosen at the discretion of the treating physicians. Second, the patients who did not have neurological deterioration tended to be lost to follow-up during the study period. This may have biased our surgical outcome. Third, our sample size was small. Each cancer type has its own disease nature and treatment response; however, we did not incorporate cancer type into the analysis due to the small sample size. All of the surgery- and instrument-related fees were covered by National Health Insurance (NIH), but a prosthesis, such as titanium wire mesh or expandable body cage, used for vertebral body reconstruction was not. This factor might have also biased the results.
In conclusion, surgery can improve the neurological outcome of spine metastasis as the first manifestation of malignancy, and debulking surgery was shown to provide better neurological recoveries and OS. Thus, debulking surgery rather than palliative surgery can be considered first when clinical information is limited and a patient is a suitable candidate for aggressive surgery.