SPARC expression in patients with high-risk localized soft tissue sarcoma treated on a randomized phase II trial of...

Treatment for localized soft tissue sarcoma includes surgery and radiation, while the role of chemotherapy is controversial. Biomarkers that could predict therapeutic response or prognosticate overall survival (OS) are needed to define patients most likely to benefit from systemic treatment. Serum protein acidic and rich in cysteine (SPARC) is a matricellular glycoprotein that has been evaluated as a potential biomarker in numerous malignancies given its involvement in cell adhesion, proliferation, migration, and tissue remodeling.

Using primary biopsy and resection specimens from patients with high-risk localized, soft tissue sarcoma treated on a neo/adjuvant chemotherapy study, SPARC expression was assessed and compared to patient and tumor characteristics, treatment, and outcomes. Survival functions were estimated using the Kaplan-Meier method and compared using the log-rank test. The Cox model was used for multivariate analysis.

Fifty patients had primary tumor specimens available. High, low, and no SPARC expression was found in 22, 13, and 15 patients, respectively. There was no significant difference in time to recurrence or OS between patients in these three groups. Comparing lack of SPARC expression with any SPARC expression, there was no significant difference in time to recurrence in patients without SPARC expression (n = 15) compared to patients with SPARC expression (n = 35). Likewise, there was no statistically significant difference in OS in patients without SPARC expression versus patients whose tumors expressed SPARC.

Although we did not find a statistically significant difference in time to recurrence and OS in patients with high-risk soft tissue sarcoma, we did identify a trend toward improved time to recurrence and OS in patients whose tumors lacked SPARC expression. However, SPARC did not demonstrate the ability to discern which high-risk patients may have a worse prognosis or greater benefit from chemotherapy.

The trial was registered on September 13, 2005 with ClinicalTrials.gov, number https://clinicaltrials.gov/ct2/show/NCT00189137?term=sarcoma&id=NCT00189137&state1=NA%3AUS%3AMI&phase=1&rank=1 .