The aim of this study was to provide a detailed evaluation of the clinical profiles, perioperative outcomes, and short-term survival following different extents of surgical intervention—biopsy, subtotal resection, and GTR—in patients with ISCM. Evidence-based surgical strategies remain challenging, and our study contributes critical insights to the ongoing debate regarding optimal management.

Surgical extent and survival

Our comparative analysis underscores the nuanced balance between aggressive surgical intervention and patient-specific conditions. Notably, patients undergoing GTR exhibited the lowest early mortality (13% at 90 days) compared to subtotal resection (60%) and biopsy-only (33%). This might suggest superior survival with aggressive tumor removal. However, deeper analysis reveals crucial selection biases: GTR-eligible patients had higher KPS scores (mean KPS 75% vs. 54–63% in other groups). Additionally, biopsy-only cases typically had disseminated disease (e.g., leptomeningeal spread or multiple lesions), limiting their prognosis and treatment options. Logistic regression showed that EOR was not independently associated with three-month survival (p = 0.834), indicating survival benefits likely reflect favorable baseline profiles rather than surgical extent. This underscores the confounding impact of patient selection bias in ISCM surgical outcomes and aligns with emerging literature emphasizing individualized patient factors.

A recent systematic review examining ISCM from lung carcinoma similarly concluded that GTR did not provide significant survival advantages over subtotal resection; rather, surgical intervention itself—regardless of radicality—was beneficial compared to non-operative approaches [12]. This review highlighted that symptomatic relief and functional preservation from surgical decompression had greater prognostic relevance than the extent of tumor removal. Correspondingly, Gazzeri et al. also reported no significant survival difference between subtotal and total resections for ISCM, emphasizing symptom management and neurological stability as key outcome drivers [11]. Our results further stress the importance of individualized surgical decision-making. Aggressive GTR may offer benefits in selected cases with isolated lesions and good neurological status, as maximal resection can potentially reduce symptom burden and local disease progression. Conversely, in patients with extensive metastases or poor neurological function, aggressive surgery offers limited clinical benefit. In such scenarios, limited decompression or diagnostic biopsy to preserve function and reduce perioperative morbidity appears more prudent.

Prognostic factors for survival

Our analysis did not demonstrate significant associations between survival and commonly considered prognostic factors such as age, sex, preoperative Karnofsky score, or neurological grade. While these factors are typically prognostic across oncology populations, the absence of measurable impact in our cohort likely reflects advanced cancer stages and the overall poor prognostic of ISCM. The small sample size further limits conclusions and underlines the necessity for cautious interpretation. Nonetheless, literature reveals several prognostic factors consistently associated with survival following ISCM surgery. Notably, surgical intervention itself emerges repeatedly as a critical determinant of improved survival compared to conservative management. Dam-Hieu et al. reported significantly longer median survival in surgically treated patients (7.4 months) vs. non-surgically managed ones (2.6 months) [20]. Similarly, Goyal et al. observed a doubling in median survival - from 3 to 6 months, with surgical intervention, particularly in patients with solitary metastases and no brain metastases [19]. Wu et al. also identified surgery as an independent protective factor for survival in lung cancer-associated ISCM, underscoring the benefit of surgical decompression in specific subgroups [12].

Additionally, postoperative neurological improvement consistently appears as a strong prognostic marker: Wu et al. (2022) found significant survival advantages linked explicitly to postoperative neurological symptom relief (HR = 0.212, p < 0.001), indicating that decompression and functional preservation might outweigh EOR as the key outcome drivers [12]. These findings highlight symptom management and neurological function preservation as central surgical goals. Other relevant factors related include disease extent and MRI-based tumor characteristics. A retrospective study of 61 patients treated with radiotherapy found longer survival when only one spinal cord segment was involved [30]. Similarly, extensive T2 hyperintensity (≥ 3 segments) and multiple intramedullary lesions correlated with shorter median survival, illustrating the potential prognostic relevance of MRI features [14]. These imaging biomarkers may aid clinical decision-making and treatment stratification. Tumor histology findings remain inconsistent, likely due to methodological differences and small cohorts. Lung cancer histology was associated with worse prognosis in one analysis [11], whereas melanoma metastases appeared to predict comparatively favorable survival in another series [27]. Such discrepancies highlight the complexities in evaluating histological impacts within limited patient samples.

In our cohort, analysis of primary histology and adjuvant therapy impact was not feasible due to small patient numbers. However, given the frequent presence of brain or leptomeningeal metastases, these additional metastatic burdens undoubtedly influenced survival. While previous studies found meningeal involvement [11] and number of metastatic organs [27] to be non-significan, these findings warrant careful interpretation due to their limited statistical power. In summary, our findings and the broader literature emphasize surgical decompression and symptom relief as primary prognostic factors in ISCM management, surpassing EOR. Larger-scale studies remain critical to identify and validate prognostic markers and guide more precise, evidence-based surgical strategies for this challenging patient population.

Perioperative complications and neurological deterioration

One of the most important findings of our study was the low perioperative risk: Our cohort experienced neither intraoperative mortality nor severe complications. Postoperative complications were manageable, such as one wound infection, successfully treated with antibiotics and debridement. Furthermore, we observed no permanent neurological deficits linked to surgery. These favorable results reflect substantial advances in neurosurgical techniques, intraoperative neurophysiological monitoring, and preoperative imaging, all of which have markedly improved ISCM resection safety.

Contextualized against existing literature, our findings support the current safety of surgical approaches: Gazzeri et al. [11, 13] reported neurological deterioration in 20% of their 30-patient multicenter cohort post- ISCM surgery, highlighting that neurological risks, though reduced, are not absent. This underscores the need for meticulous planning, patient selection, and intraoperative caution. Historically, Hejazi & Hassler (1998) examined 80 patients undergoing intramedullary tumor resection, noting neurological improvement in most (63/80) patients. However, among 5 metastatic cases, 60% deteriorated, illustrating the heightened risk of neurological impairment with metastatic vs. primary spinal cord tumors [25]. Such data reinforce the considerable advancements made in neurosurgery, as modern studies now report lower complication rates and improved outcomes.

Nonetheless, complications—particularly CSF leaks and infections—remain relevant and require postoperative vigilance. Several authors reported postoperative complications such as CSF leaks and wound infections [21, 26]. Conversely, most recent studies show minimal surgical complications. Multiple series report no surgical complications, emphasizing advances in (peri-)operative care [12, 22, 23, 28, 29]. Collectively, our data and the literature highlight reduced morbidity and enhanced surgical safety. Nevertheless, surgical decisions must carefully balance benefit with residual risks of neurological decline and other complications. Continued advancements and broader experience will further refine patient selection and techniques, enhancing ISCM surgical safety.

Recent series demonstrate that carefully selected patients can achieve favorable neurological and functional outcomes [27, 28]. Modern studies report that the majority of patients experience neurological preservation or improvement postoperatively: for example, one multicenter analysis noted symptom improvement in ~ 60% of cases (with partial recovery of motor/sensory function and pain relief) and deterioration in only ~ 20% [11] and all patients who were ambulatory preoperatively remained ambulatory after surgery in another cohort [27]. New permanent neurologic deficits are relatively infrequent – permanent postoperative worsening is observed in roughly 10–20% of patients across studies [11, 27]. Importantly, outcomes are influenced by patient and tumor factors: those with milder preoperative deficits and lesions in favorable locations (e.g., dorsally located or cervical tumors) tend to have better recovery, whereas severe preoperative paralysis or tumors involving the thoracic cord portend poorer neurologic improvement [31].

Integrating systemic therapy and surgery in the management of ISCM

In light of modern oncologic therapies, surgical indications for ISCM must be framed within the patient’s overall disease context. Improved systemic treatments – including chemotherapy, targeted agents (EGFR/ALK inhibitors in lung cancer, HER2-directed therapy in breast, BRAF/MEK inhibitors in melanoma), immunotherapies (checkpoint inhibitors), and advanced radiotherapy techniques – have modestly extended survival in patients with spinal cord metastases and thus influence the role of surgery [32, 33]. Our series of 16 ISCM patients underscores that surgery is most beneficial when the patient’s systemic cancer is controllable or in remission, allowing them to actualize the gains of neurological preservation. Consistent with the literature, we found that carefully selected patients who underwent resection experienced neurological improvement and a meaningful survival interval, whereas those with aggressive, refractory disease derived limited benefit [12, 13]. The availability of effective systemic options can tip the risk–benefit balance in favor of surgery – for example, resecting an intramedullary metastasis in a lung cancer patient responding to an EGFR inhibitor can prevent paralysis and yield survival beyond historically grim expectations [12]. Conversely, in patients with disseminated malignancy lacking further treatment lines, a less invasive approach (such as palliative stereotactic radiosurgery or best supportive care) may be prudent. Notably, emerging modalities like spinal stereotactic radiosurgery now offer a non-surgical means to obtain local control in select cases, and retrospective data suggest combining surgery with adjuvant radiation can maximize disease control for those fit enough [32]. Ultimately, integrating systemic therapy with local treatment is critical: surgery should be seen as one component of a multimodal strategy, deployed when it aligns with the patient’s oncologic trajectory. This nuanced approach – selecting surgical candidates based on tumor biology, systemic therapeutic options, and performance status – is essential for optimizing outcomes in ISCM, as our findings illustrate. In practice, a multidisciplinary assessment (neurosurgery, oncology, radiation oncology) is warranted for each case, ensuring that surgical intervention is offered when it meaningfully improves neurological function and complements the patient’s overall cancer management [34,35,36].

Limitations and future directions

This study’s primary limitations are its retrospective design and small sample size (16 patients), limiting statistical power to detect subtle but clinically relevant prognostic associations, such as those related to Karnofsky Performance Status (KPS), tumor volume, or preoperative neurological function. The absence of prognostic significance for these factors should be interpreted cautiously, as larger cohorts may reveal associations missed here. Also, key prognostic factors—such as leptomeningeal progression, CSF cytology, systemic disease burden, and local recurrence timing—could not be consistently assessed. Prospective data collection and structured follow-up would allow deeper insight into their impact on surgical candidacy and outcomes. Selection bias is inherent due to the non-randomized nature of our methodology; surgical strategies (biopsy, subtotal, or total resection) were based on clinical judgment and patient-specific factors rather than prospective allocation. This likely confounds direct outcome comparisons, as patients undergoing aggressive surgery differed in baseline status from those receiving conservative treatment. In this context, tumor histology and systematic postoperative adjuvant treatments may confound these survival analyses. Future studies should employ multicenter collaborations and prospective registries to enhance statistical power and better define prognostic factors. Larger-scale studies stratified by tumor type and clearly defined treatment regimens would also be needed to specifically draw conclusions regarding survival outcomes between GTR and STR approaches. Identifying which patients benefit most from aggressive surgery versus conservative or systemic approaches, and incorporating standardized assessments of quality of life and neurocognitive function, remains a critical goal given the significant functional impact of ISCM.