Evaluation of newer prognostic markers for adult soft tissue sarcomas

In addition to tumor size, grade, location, and the presence of metastases, other factors may be useful in prognostication for adults with soft tissue sarcoma (STS). This study examines the relationship of MDR-1 mRNA, p-glycoprotein (P-gp), Ki-67 expression, and DNA content expression to clinical outcome in adults with STS.

Snap-frozen STS specimens from 65 patients were analyzed and compared with clinical outcomes. Immunohistochemistry was performed for the Ki-67 antigen and P-gp. DNA content was determined using the Feulgen reaction and quantitated using image analysis. MDR-1 mRNA expression was determined using a reverse-transcriptase polymerase chain reaction (RT-PCR)-based assay.

P-glycoprotein expression was found by immunohistochemistry in 48% of cases with 5-year overall (54% v 14%, P = .07) and disease-free survival rates (32% v 18%, P = .039) higher in high-grade tumors that did not express P-gp. MDR-1 mRNA was detected in 51% of cases and no patient with high levels of MDR-1 mRNA expression was a long-term survivor. Patients with diploid tumors had significantly better survival than those with nondiploid tumors (51% v 31%, P = .03). High levels of Ki-67 were associated with poorer overall survival (46% v 31%, P = .04). On multivariate analysis, American Joint Committee on Cancer (AJCC) staging, DNA content, Ki-67, and P-gp staining were significant prognostic factors for 5-year overall and disease-free survival.

P-gp expression, high-level Ki-67 expression, and nondiploid DNA content are independent prognostic indicators that correlate with poor outcomes in STS patients. However, MDR-1 mRNA was not found to be predictive of survival. These newer markers are useful additions to AJCC staging for prognostication for patients with STS. Such markers may be useful in selecting high-risk STS patients who could benefit from systemic adjuvant therapy.