Spinal metastases are an end-stage manifestation of the cancer disease process, and according to most modern studies, the one-year survival rate is 50%. At diagnosis, most patients are suffering severe pain, neurologic symptoms and ambulatory impairment.
Over the last 15 years, surgical treatment has been touted as a means to preserve quality of life and independence in patients with spinal metastases and improve their chance of survival. However, most of the limited studies of surgery in this setting have been retrospective, short-term and prone to confounding by indication.
By leveraging data from the Prospective Observational study of Spinal metastasis Treatment (POST), researchers at Brigham and Women’s Hospital examined the two-year natural history of spinal metastases in a wide range of cancer patients treated operatively or non-operatively in the same clinical setting.
Andrew J. Schoenfeld, MD, MSc, a surgeon in the Department of Orthopaedic Surgery at the Brigham, Grace X. Xiong, MD, a resident physician in the department, and colleagues report in Spine (Phila Pa 1976) that both types of treatment yielded improvements in health-related quality of life. There was no survival advantage with surgery, and the overall mortality rate was sobering: 70% of patients died within two years.
The multicenter POST study was designed to evaluate the New England Spinal Metastasis Score (NESMS), a prognostic tool that considers primary tumor characteristics, metastatic burden, general health (via albumin) and ambulatory ability. It ranges from 0 to 3 (best). The NESMS has been validated as being capable of predicting survival at one year for patients with spinal metastases, as reported in The Spine Journal.
POST was launched on July 1, 2017, and patients were evaluated one, three, six and 12 months after treatment was initiated. Survival was tracked through month 24 and the study was completed on July 31, 2021. For the natural history analysis, the researchers analyzed the records of all 202 participants.
Characteristics of the Cohort
The most common primary tumor types in POST were lung cancer (20%), breast cancer (18%) and prostate cancer (14%). 31% of patients had metastases in multiple spinal regions. 58% were independently ambulatory at presentation, and 71% were neurologically intact.
The most common non-operative treatment was combined chemotherapy and radiation (79%). The most common surgical strategy was a fusion-based procedure (79%), and 30% of the entire cohort also had a corpectomy. 55% of surgically treated patients also underwent chemotherapy and radiation.
The average survival was 248 days, with 25% of patients surviving 76 days or less. 23% died within three months after treatment initiation, 37% within six months, 51% within one year and 70% by the time of study completion. There was no significant difference in survival between patients treated surgically versus non-operatively.
Complications of special interest were recorded at one- and three-month visits. The complication rate at three months was 21% for the cohort as a whole and was significantly greater for patients managed non-operatively (28% vs. 13% for surgically treated patients; P=0.009). The most common study-specific complications in both cohorts were venous thromboembolism and pneumonia.
Quality of Life
As measured on the EuroQol-5 dimension (EQ-5D), health-related quality of life was significantly lower in the surgical cohort than in the non-operative group at baseline.
Improvements in EQ-5D were observed in both groups, but scores in the surgical cohort were comparable to those in the non-operative cohort three months after treatment initiation. There were no significant between-group differences thereafter.
Determinants of Mortality
In a multivariable analysis adjusted for potential confounders, the only clinical/sociodemographic characteristics significantly associated with mortality were:
- NESMS score of 0 (HR, 5.61; P<0.001)
- NESMS score of 1 (HR, 3.00; P=0.001)
- Age of 61–71 (HR, 0.52; P=0.03)
Guidance for Physicians
These findings imply surgery for spinal metastases is best reserved for patients who are likely to benefit demonstrably in terms of quality of life, maintenance of ambulatory function, maintenance of neurologic function or pain reduction.
The NESMS appears to be effective for predicting survival regardless of the type of treatment, particularly for patients with scores of 0 or 1. At time points beyond one year, the discriminative ability of NESMS scores 2 and 3 may be diminished, given the limited life expectancy of patients with spinal metastases.