The Prognostic Factor of Malignancy of Undefined Primary Origin in Spinal Metastases
Authors: Daniel Jefferson W. , Veiga José Carlos Esteves 
Published: May 2015

Introduction Malignancy of undefined primary origin is metastatic malignancy identified on the basis of a limited number of tests, without an obvious primary site, before comprehensive investigation.2 Patients who harbor spinal epidural neoplastic 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 postoperative survival period seems reasonable for the decision-making process regarding whether surgery should be performed. The physician may reason that if the knowledge of the primary tumor site is not a prognostic factor for survival in preoperative urgent surgery for spinal epidural neoplastic metastases, then surgery must not be postponed. The objective of this study is to compare the postoperative survival between patients with defined and undefined malignancy of primary origin as a prognostic factor for survival in spinal metastases. 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. The inclusion criteria were as follows: known postoperative survival period, a Karnofsky performance score equal to or greater than 30 points, and a postoperative neoplastic metastasis histological type. The Kaplan–Meier method was used to estimate the postoperative 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). The median survival after surgery was 70 days (95% CI: 49.97–90.02) and postoperative mortality occurred within 6 months in 38 patients (73.07%). The primary neoplasm site and histological type were unknown in 36 (69.23%) of the patients in the preoperative period. The following primary tumor types were identified after the surgery: myeloma (8 patients), lung carcinoma (6), sarcoma (5), prostate carcinoma (5), lymphoma (4), undifferentiated carcinoma (4), thyroid carcinoma (1), pineal germinoma (1), gastric adenoma (1), and kidney blastoma (1). Cancer type was the strongest overall survival indicator in this study ( p = 0.023). The median postoperative survival for the 16 patients (30.77%) with known preoperative primary tumors was 59 days (95% CI: 11.96–106.04) and it was 72 days (95% CI: 51.45–92.54) for the 36 patients (69.23%) with unknown tumors. The statistical inference was p = 0.719 and statistically insignificant for postoperative survival between the known and unknown primary tumor site. The median postoperative survival in patients with elective surgery was 76 days (95% CI: 53.571–98.429) and for urgent surgery was 45 days (95% CI: 3.553–86.447). The statistical inference was p = 0.124 for postoperative survival between the elective and urgent surgery patients. Conclusion Undefined malignancy of primary origin is not a prognostic factor for survival in patients who harbor spinal epidural neoplastic metastases when compared with those with a defined malignancy of primary origin in this research study. References Daniel JW. Survival prognostic parameters in patients with spinal column epidural metastatic neoplasms [PhD thesis]. São Paulo, SP, Brazil: Santa Casa de São Paulo, Faculty of Medical Sciences; 2013 National Institute for Health and Clinical Excellence. 2010. Metastatic malignant disease of unknown primary origin. London: NICE clinical guideline. Available at: https://www.nice.org.uk/search?q=Metastatic+malignant+disease+of+unknown+primary+origin. Accessed September 20, 2014