Necrosis on FDG PET/CT correlates with prognosis and mortality in sarcomas

The purpose of this study was to determine if there is an association between necrosis as identified on staging (18)F-FDG PET/CT and overall survival (OS) and progression-free survival (PFS) in patients with sarcoma.

Sixty-six patients with newly diagnosed limb and girdle sarcoma underwent PET/CT at our institution between June 2004 and July 2009 for sarcoma staging before treatment with curative intent. The tumor maximum standardized up-take values (SUVmax), the presence of necrosis, and the volume of necrosis were measured for each primary tumor and correlated with follow-up data. PFS and OS were analyzed using the Kaplan-Meier method. Proportional hazards models were used to estimate hazard ratios.

Median patient age was 49 years, and 51.6% of the patients were men. Sarcomas were categorized as soft tissue (69.2%), bone (23.5%), or other (7.3%). Mean follow-up time was 33.3 months. During the follow-up interval, 53% of patients experienced disease progression, and 40.9% died. There was a statistically significant relationship between the presence of necrosis and OS (by log-rank test, p = 0.001), as well as PFS (by log-rank test, p = 0.0001). Twenty-four-month OS was 96%, 65%, and 38% in patients with tumors with absence necrosis, those with presence of necrosis, and with necrosis volume greater than 50%, respectively. Forty-eight-month OS was 81% in patients with absence of necrosis and 41% in patients with presence of necrosis. Twelve-month PFS was 96%, 60%, and 42% in patients with tumors with absence of necrosis, those with presence of necrosis, and those with necrosis volume greater than 50%, respectively. Twenty-four-month PFS was 83%, 38%, and 22%, respectively, in these groups.

The presence of necrosis and the volume of necrosis, as identified on the staging FDG PET/CT and after adjusting for SUVmax, are strong independent adverse prognostic factors for disease recurrence and death in patients with limb and girdle sarcomas.