Prognostic factors for retroperitoneal sarcoma diminish after 1 year

Abbott AM. Cancer. 2012;doi:10.1002/cncr.26665.

Issue: February 10, 2012

Tumor and patient characteristics that can predict prognosis after resection of retroperitoneal sarcoma lose their significance after 1 year of survival, according to study findings published in Cancer.

Researchers used SEER registries to conduct a retrospective study of 1,199 patients who underwent surgical resection for nonmetastatic retroperitoneal sarcoma from 1988 to 2007. They used Cox proportional hazards regression to determine the effect of several factors on sarcoma-specific survival at baseline and 5 years after diagnosis.

They determined that male gender, older age and histologic subtype — all of which predicted worse sarcoma-specific survival at the time of diagnosis — no longer were significant predictors after 1 year of survival.

“This large population-based study … demonstrates that variables contained within the American Joint Committee on Cancer staging system and current postoperative nomograms do not adequately predict continued survival in persons who have survived years after their initial retroperitoneal sarcoma diagnosis,” Andrea M. Abbott, MD, of the University of Minnesota in Minneapolis, and colleagues wrote.

Only high tumor grade, another factor that predicted worse sarcoma-specific survival at diagnosis, remained a significant predictor of worse prognosis after 3 years (HR=1.7; P=.004) and 5 years of survival (HR=1.95; P<.02), researchers found.

Race, receipt of adjuvant radiation therapy, nodal disease and tumor size were nonsignificant predictors of survival.

"The current work provides the first framework to help clinicians counsel survivors of retroperitoneal sarcoma," the researchers wrote. "By demonstrating how demographic and tumor factors vary in significance over time, we highlight which variables remain prognostic at specific time points in survival. This information will allow clinicians to develop patient-specific surveillance schedules and aid in the development of resource-conserving cancer survivorship programs that may improve health care utilization and enhance the quality of life for patients."

Unadjusted analysis showed each additional year of survival increased patients' chances for continued survival. At diagnosis, sarcoma-specific median survival was 83 months. After 1 year of survival, sarcoma-specific median survival increased to 98 months. After 3 years of survival, sarcoma-specific median survival increased to 177 months. More than half of the patients survived the duration of the 5-year follow-up.

The researchers said there were several limitations in the study, noting that SEER registries do not include information on resection margin status, disease recurrence or systematic chemotherapy. However, their findings are from a large nationally representative study that lasted more than 2 decades, minimizing referral and institutional biases often observed in single-center studies.

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