Page 64 - Predicting survival in patients with spinal bone metastasesL

CHAPTER IV DISCUSSION
In this retrospective study of 1043 patients treated for symptomatic SBM it is shown that the clinical profile of the primary tumor, performance status and – in the subgroup of a favorable clinical profile only – the presence of visceral and brain metastases are associated with survival. Other prognostic factors such as the presence of extraspinal bone metastases, number and location of spinal metastases and neurological functioning did not show a significant effect on survival.
The most important limitation of this study is its retrospective design. Due to the fact that all patients were treated in a single institution, clinical information was readily available, including radiology reports. However, this does not rule out the possibility of inaccuracy of the source data. Furthermore, no SBM-specific treatment protocols existed, exemplified by the fact that the landmark study by Patchell et al.2 resulted in more surgical interventions being performed in the period after publication. However, as this study analyzes survival only and therapy for SBM is not directly aimed at prolonging survival, it is unlikely that our results are influenced by this change in therapeutic approach. It is possible that the presence of brain metastases is underrepresented in this study population, as whole-brain scans were not routinely performed, contrary to thoracic and abdominal scans. As a result, most of the patients with brain metastases had symptomatic lesions. It is unclear whether asymptomatic brain metastases have the same predictive value in this specific patient population. Lastly, in our institution treatment for SBM only takes place in symptomatic patients and only patients treated locally for their SBM by means of surgery or radiotherapy were included. As a consequence, patients with symptomatic SBM that received only supportive care no are not represented in this study.
In contrast to the previous study by our group – which was based on a prospective database with only radiotherapy patients - patients with a cervical located SBM were not excluded, nor were patients with renal cell carcinoma, leading to better generalizability of the data. Because the prospective DBMS database was closed after an inclusion period of 2.5 years, median follow-up times are distinctly different. Survival times in category A are therefore limited. Since the DBMS inclusion criteria were stricter and contained more patients with a favorable clinical profile and fewer with an unfavorable profile, median survival times were
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