The Use of Secondary Prognostic Parameters when Malignancy of Undefined Primary Origin is Present in Spinal Metastases

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Introduction Accurate prognostication is not feasible when the primary malignancy is unknown. Patients who harbor spinal metastases with malignancy of undefined primary origin are common in the clinical scenario of installed paraplegia within 24 hours or rapid progressive paraparesis. Acute spinal nervous tissue compression is an indication for urgent surgery and should be performed within 24 hours of hospitalization. In this urgent clinical situation, time-consuming neoplastic disease staging may not be feasible. An estimated 3-month post-operative survival period seems reasonable for the decision-making process regarding whether surgery should be performed. When the primary malignancy site is unknown, secondary parameters are used to estimate patient survival. Special patient care dependency, spinal cord tumor compression, walking impairment, urgent surgery, and malignancy of undefined primary origin can be used to estimate survival and can act as secondary prognostic parameters of survival. The objective of this study is to identify pre-operative prognostic parameters for survival in patients with spinal metastasis when malignancy of undefined primary origin is present. Material and Methods This study was a retrospective chart review of patients who underwent surgery for spinal epidural neoplastic metastases between February 1997 and January 2011. Inclusion criteria: Knowledge of the post-operative survival period. Five pre-operative prognostic parameters for patient survival where identified: Special care dependency (Karnofsky Performance Score ≧30 points); Spinal cord tumor compression (MRI/TAC spinal imaging); Walking impairment ( ASIA Scale A & B); Urgent surgery; Malignancy of undefined primary origin. Statistical analysis compared patients with the selected five prognostic parameters for survival to those with one to four of these prognostic parameters. The Kaplan–Meier method was used to estimate the post-operative survival and the log-rank test was used for statistical inference. Results A total of 52 patients who underwent 52 surgical procedures were identified. The mean age at the time of spinal surgery was 53.92 years (standard deviation 19.09). Malignancy of undefined primary origin was present in 36 (69.23%) of the patients in the preoperative period. The overall median survival after surgery was 70 days (95% CI: 49.97–90.02) and post-operative mortality occurred within 6 months in 38 (73.07%) patients. The median post-operative survival for the 16 (30.77%) patients harboring the selected five prognostic parameters to estimate survival was 22 days (95% CI: 4.36–39.64) and for the other 36 (69.23%) patients with one to four of the prognostic parameters, 72 days (95% CI: 57.30–86.70). The mean post-operative survival for the same 16 (30.77%) patients harboring the selected five prognostic parameters to estimate survival was 109.75 days (95% CI: 107.49–251.27) and for the other same 36 (69.23%) patients with one to four of the prognostic parameters, 210.33 days (95% CI: 118.46–302.20). Statistical inference for the five analyzed prognostic parameters was p-value = 0.123 Conclusion Patient special care dependency, spinal cord tumor compression, walking impairment, urgent surgery and malignancy of undefined primary origin are useful as secondary prognostic parameters for patient survival. A 2- to 3-month post-operative survival period justified surgical treatment in this study.