Background: Traditionally, grade is considered the most important prognostic factor for soft tissue sarcomas (STS). However, because of the alleged difficulties in reproducibility of grading, new, objectively determined prognostic factors would be of value. The aim of our study was to establish if S-phase fraction (SPF) measured with flow cytometry was of prognostic significance for STS.
Methods: In this study, we included all 193 adult STS patients with superficial trunk or limb tumors who were treated by the Helsinki University Central Hospital (HUCH) STS group between January 1987 and May 1993. One hundred and seventy-two formalin fixed paraffin embedded tumor samples were available. SPF measurement was successful in 155 cases.
Results: Eighty-six cases were diploid. Ploidy was found to have no effect on overall survival. The median SPF was 6.8% (diploid tumors, 4% and nondiploid tumors, 12.9%). A high SPF predicted a shorter survival in patients with diploid tumors (P=0.003). The prognostic value was even stronger when we studied disease specific survival and excluded from analysis samples that contained less than 50% tumor cells (P=0.011). However, no prognostic value could be detected in nondiploid tumors or in the material as a whole.
Conclusions: Our results suggest that high SPF is an adverse prognostic factor for survival of patients with diploid STS. However, further studies are needed to confirm these results.