The development of new therapies and screening tests have increased the survival of oncological patients, and consequently, the incidence of metastatic lesions of the spine.1–3 The objective of the treatment of these lesions is the maintenance of quality of life based on the four following pillars: pain relief, maintenance of neurological function, spine stability, and local control of the disease.4,5
Surgery in vertebral metastases is considered a palliative treatment reserved for patients with a life expectancy of >3 months who can tolerate the procedure. Patients with severe pain due to instability may benefit from surgical procedures for stabilization/decompression after multidisciplinary analysis.5–7 Thus, the knowledge of factors related to the functional prognosis of these patients is imperative.
The present study aims to evaluate the epidemiology of surgical patients with spinal metastases, identify the complications of the procedure and their relationships with the other epidemiological variables, and evaluate their neurological prognoses.
MATERIALS AND METHODS
A retrospective cohort of patients was surgically treated at the Hospital das Clínicas of University of Campinas for spinal metastases from January 2010 to September 2018.
Inclusion criteria were all patients hospitalized in the period described above and who had the following characteristics: patients surgically treated for spinal metastases, survival over 3 months estimated by the Clinical Oncology team and postoperative follow-up at the same hospital. The procedures were performed by the same surgeon (A.F.J.). Patients who did not undergo surgical treatment, patients whose data were not found or were insufficient for analysis, and patients with hematological diseases were excluded from the study. After the analysis of the exclusion criteria, the sample obtained comprised 40 patients.
The clinical data of the patients and those referring them for the procedure were collected retrospectively from the charts of the selected patients. Demographic, clinical, and histological data were collected, as well as surgical and oncological treatment information. All patients were followed until the date of death or until the last follow-up visit before the data analysis, in case of living patients.
Surgical treatment was performed after diagnosis of symptomatic spinal cord compression (SCC) and/or mechanical instability of the spine. The neurological function was classified based on the Frankel index8 in the preoperative period and 4 weeks postoperatively. The patients were stratified into the three following groups: complete neurological deficit (Frankel A), incomplete deficit (Frankel B, C, and D), and no neurological deficit (Frankel E). The deterioration or improvement of motor function was defined as a change of at least one level in the Frankel index.
Retrospectively, we analyzed the charts and applied the SINS score9 to evaluate the presence of mechanical instability of the spine. Lesions were considered stable at 0–6 points, potentially unstable at 7–12 points, and unstable at 13–18 points.
After the data were collected, hospitalization and its relationship with the performance of spinal instrumentation, the occurrence of complications and postoperative functional outcomes were analyzed. The data obtained were processed with SPSS software for MacOS version 21.0 (Statistical Package for the Social Sciences, SPSS Inc, Chicago, IL). To verify the normality of the quantitative variables, the Kolmogorov–Smirnov test and Shapiro–Wilk test were applied. Qualitative variables were presented in absolute and relative values. For the evaluation of the association between the variables, the Chi-square test, Fisher exact test, or Fisher–Freeman–Halton test was applied. For evaluating the improvement of neurological status between the Frankel scores before and after surgery, the McNemar test was applied for categorical and qualitative variables. The study was initiated after approval by the research ethics committee of UNICAMP under the number CAAE: 49071115.3.0000.5404.
A total of 40 patients underwent surgery for spinal metastases between 2010 and 2018. The mean age of the patients was 54.4 years (range: 23–76 yr). Twenty-three (57%) were male. There was a large distribution of histological types of the primary tumor, with breast, lung, prostate, colon, and hepatic carcinomas being the five most common types representing 25 (62.5%) cases. The mean follow-up was 12 months (95% CI: 8.93–15.110).
Pain, defined as either axial pain or radicular pain, was the reason for visiting a primary care provider in 25 cases (55.6%), and the duration of the symptoms until the surgery lasted an average of 30.95 days (range: 1–180 d). Metastatic lesions were more commonly located in the thoracic spine in 23 (57.5%) patients followed by lumbar spine in eight (20%) patients. Thirty-six surgically treated patients had at most three metastases (90%). The stability of the spine was evaluated using the SINS score, with seven (17.5%) patients stratified at 0–6 points, 21 (52.5%) at 7–12 points, and finally, 12 (30%) at 13–18 points.
By analyzing the preoperative imaging tests, it was found that 13 (32.5%) of the cases presented vertebral body collapse and eight (20%) patients presented deformity—comprising seven (17.5%) patients with kyphotic deformity and one (2.5%) with scoliotic deformity. Metastases were uniquely epidural in 24 (60%) cases. Neurologically, in the preoperative period, 26 (65%) patients had incomplete neurological deficit, being classified as Frankel B, C, or D; 5 (12.5%) patients had complete deficit (Frankel A); and nine (22.5%) were classified as Frankel E, that is, neurologically intact.
Instrumentation of the spine was performed in 22 (55%) patients who underwent operation and were considered with mechanical spinal instability. Eighteen (45%) patients presented with symptomatic spinal cord compression (SCC) and three (7.5%) patients presented with spinal instability without neurological symptoms. Laminectomy and circular decompression were performed in all patients with SCC. A posterior surgical approach was used in all cases.
Adjunctive radiotherapy at the surgery site was performed in 40 patients (100%). Chemotherapy was performed with adjuvant therapy in 36 patients (90%).
Within 30 days after surgery, five patients (11.1%) had complications, which were as follows: deep vein thrombosis or pulmonary embolism (two patients, 5% of the total), respiratory failure (one patient, 2.5%), pneumonia (one patient, 2.5%), and wound infection (one patient, 2.5%). No reoperation was performed within 30 days.
The presence of complications did not have a statistical correlation with the preoperative characteristics. Table 1 shows the epidemiological characteristics and complications.
Relationship Between Instrumentation and Epidemiological Characteristics
Among the patients evaluated, 22 (55%) underwent instrumentation and spinal arthrodesis. Of these, three (13.6%) presented complications, while two (11.1%) of the patients who did not undergo arthrodesis had complications. There was no significance between complications and surgical instrumentation compared with decompression surgery in our series (P = 0.816).
Among the patients in whom pain was the reason for seeking care, 16 (72.7%) were submitted to instrumentation (P = 0.024). Regarding the instrumentation and the retrospective application of the SINS score, there was statistical significance corroborating that a higher SINS score corresponded to the indication for instrumentation surgery due to the instability of the spine as shown in Figure 1 (P = 0.004).
After image analysis, 11 (52.4%) patients with vertebral body collapse were submitted to arthrodesis surgery (P = 0.008). Among the patients without spinal deformity, 15 (46.8%) were instrumented; in the presence of misalignment, six (85.7%) patients with kyphotic deformity, and one (100%) with scoliotic deformity were submitted to instrumentation (P = 0.0042), as shown in Table 2.
As shown in the tables below, 14 (35%) patients showed improvement of at least one level in the Frankel classification after surgery. Among the five patients with complete preoperative deficit, three (60%) presented partial improvement of the deficit to incomplete deficit (Frankel B–D). Among the 26 (62.2%) cases with incomplete deficit (Frankel B–D), nine (34.6%) exhibited total neurological recovery (Frankel E) and only one (3.8%) had neurological worsening and presented as Frankel A in the late postoperative period. The patient who had neurological worsening was a 59-year-old with prostate metastatic adenocarcinoma and presented with spinal cord compression and incomplete deficit (Frankel B). During surgical decompression he had severe arterial hypotension and postoperatively had a complete deficit probably due to spinal cord hypoperfusion added to spinal cord compression. Finally, in the preoperative evaluation, 9 (22.5%) patients were neurologically intact, while in the postoperative evaluation, 20 (50%) patients had no deficit (Frankel E). As shown in Table 3, there was a statistically significant neurological improvement of the patients who underwent surgery (P = 0.002), but there was no statistical correlation between the epidemiological characteristics studied and the presence of neurological improvement, as shown in Table 4.
Relationship Between Pain as a Reason for Seeking Initial Care and Mechanical Instability of the Spine
Of the 40 patients evaluated, 22 (55.0%) presented pain (axial or radicular) as the main reason for seeking initial medical care. Relating the presence of pain with the SINS score for assessing the mechanical stability of the spine in metastases, pain was present in 3 (13.6%) patients with SINS scores of 0–6 points, 8 (36.4%) patients with scores of 7–12, and 11 (50.0%) patients with scores of 13–18, that is, with instability of the spine according to the SINS score, as shown in Figure 2. This suggests that the greater the instability, the greater the chance of presenting with pain clinically. After statistical analysis, the presence of pain as a reason for seeking care was found to have a positive correlation with the presence of mechanical instability of the spine using the SINS score (P = 0.009).
Among the patients in whom pain was a reason for initially seeking care, 16 (72.7%) underwent surgery with instrumentation and arthrodesis. Pain as the reason for the first visit presented an odds ratio (OR) = 2.44 (95% confidence interval [CI]: 1.14–5.2) for instrumentation need (P = 0.024). Analyzing the imaging tests, patients with pain were more likely to present collapse of a vertebral body as shown in Figure 3, with an OR = 3.75 (95% CI: 1.0–13.9; P = 0.017). Alignment and characteristics of bone lesions did not present a correlation with pain at the initial clinical presentation, as demonstrated in Table 5.
This study examined the characteristics, outcomes, and complications of surgeries for spinal metastases at our institution. Patients who presented mechanical pain as an initial symptom, presence of deformity secondary to metastasis, or collapse of the vertebral body were correlated with the instrumentation associated with decompression surgery. The retrospective classification by the SINS score showed a direct relationship with the performance of instrumentation in our sample. In relation to neurological deficit, this study demonstrates that there is benefit in performing surgery in patients with a neurological deficit.
Pain was the reason for initially seeking care in 55% of the cases, and this is related to the fact that pain is the first symptom of epidural spinal cord metastases (ESCM) in up to 96% of patients. In 2003, Levack et al10 performed a prospective observational study in which they evaluated the diagnosis, management, and prognosis of 319 patients treated between 1998 and 1999; they reported that most patients (94%) had pain as the first symptom and sought care in the primary care setting an average of 66 days before the diagnosis was made.10–13
The posterior approach surgical procedure with laminectomy and decompression was performed in all SCC patients by epidural spinal cord metastases (ESCM), and instrumentation was employed in 55% of the patients who were diagnosed with mechanical instability of the spine during the preoperative evaluation. Correlating the preoperative characteristics and surgical procedure, we noticed that the preoperative surgical evaluation of the stability of the vertebral column presented a direct correlation with the retrospective application and scoring of the SINS (P = 0.004); here, patients with higher scores—91% of patients with SINS 13–18—underwent instrumentation concomitantly with the decompression of the spine. This correlation is important, since it corroborates the use of the SINS score in our population, giving more objective criteria for a correct indication for the surgery, especially for more inexperienced surgeons, as proposed by Fisher et al in describing the SINS score.14
The rate of complications described in the literature is up to 39%, with postoperative infection rates of up to 30%; these values are higher than those found in our study, in which the complication rate was 11.1%. Among the patients with complications in this study, wound infection occurred in one (2.5%) and thromboembolic events in two (5%) cases, and no reoperation was required within 30 days.14–16 There was no relationship between postoperative radiotherapy and complications. In contrast, in 2009, Demura et al retrospectively evaluated 110 patients surgically treated by SCC for spinal metastases for analyzing complications and reported that the rate of adverse effects in irradiated patients was 32%, while in nonirradiated patients, it was 1% [55,66]. There was no correlation between the performance of surgical instrumentation with the occurrence of complications.
Among the patients who reported pain as a reason for seeking care, 72.7% underwent arthrodesis surgery, presenting an OR = 2.44 (95% CI: 1.1–5.2; P = 0.004), a fact corroborated by the positive correlation among the presence of pain in 91% of the patients with mechanical instability evidenced by the SINS score (P = 0.009). The same finding was reported by Cavalcante et al,15 in which the presence of pain in the 79 patients evaluated with SCC by ESCM correlated with a higher SINS score (P = 0.001). Analyzing the imaging tests, the presence of deformity, mainly kyphotic, and collapse of the vertebral body also showed a positive correlation with the performance of spinal instrumentation and arthrodesis (P = 0.042 and P = 0.008, respectively).
In our cohort, 11 patients who presented with incomplete deficit (Frankel B–D) had deficit reversal after surgery (Frankel E), and two patients with complete neurological deficit (Frankel A) had partial recovery of the deficit (Frankel B–D). In this sample, the neurological state was improved, as shown by the Frankel scale, in relation to the preoperative classification; this has also been demonstrated by several authors in the literature (P = 0.002). However, no variable presented statistical correlation as a predictor of neurological improvement. These data are consistent with the study by Patchell et al; in this study, among 101 randomized patients, the 51 patients who underwent surgery recovered their function in 62% of the cases, while only 19% of the cases submitted to radiation concluded that surgery is functionally superior, in terms of neurological recovery, to radiotherapy isolated in metastases of the vertebral column.16
In a recent study by Hohenberger et al in which they reviewed 94 surgically treated patients with spinal metastases, they reported that pain significantly improved comparing admission to discharge (P = 0.019), as well as motor deficits (P = 0.003). Predictors of poor outcome were Karnosky Performance Index < 70, male sex, multiple metastases and pre-existing bowel and bladed dysfunction. The mean follow-up was 2 months in this series, suggesting potentially more severe disease than our study.17 Improving in quality of life was also reported in the study of Abdelbaky et al that evaluated 70 patients who underwent surgical intervention for spinal metastasis. They reported total pain relief in 16 patients (24%) and pain levels decreased in 38 patients (58%). The survival rate was 71% at 3 months and 49% at 1 year, with 13 patients nonambulant before surgery able to walk after the procedure.18 Both studies suggested that surgery can be very helpful to selected patients with spinal metastases.
Our study had some limitations. For instance, it was a single center, small sample study that was retrospective in nature, and it did not evaluate patients who did not undergo surgery. However, it still provides important information regarding the complication rate and neurological prognosis of patients with spinal metastases.
In our series, pain as the first symptom was related to mechanical instability of the spine and the performance of instrumentation. The stratification of the patients by SINS score showed a correlation with instrumentation performance. Patients presented improvement of the neurological function postoperatively, but no predictive factors of this improvement were found other than the initial neurological status.
The performance of spinal instrumentation was not associated with an increase in the incidence of complications compared with isolated decompression laminectomy, with our complication rate being lower than the literature average.
- The objective of the treatment of spinal metastases is the maintenance of quality of life based on the four following pillars: pain relief, maintenance of neurological function, spine stability, and local control of the disease.
- Pain as the first symptom was related to mechanical instability of the spine and the performance of instrumentation.
- The stratification of the patients by SINS score showed a correlation with surgery with instrumentation.
- The patients presented improvement of the neurological function in the postoperative period.
- The performance of spinal instrumentation was not associated with an increase in the incidence of complications in this cohort.
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