Solitary Fibrous Tumour: A Single Institution Retrospective Study and Further Validation of a Prognostic Risk...

Solitary fibrous tumour (SFT) is a rare mesenchymal-derived neoplasm that can arise in any anatomical location in the body. SFT rarely metastasises, but aggressive behaviour is seen in a minority of cases, and relapses can occur several years after treatment. It would be a clinical advantage if high-risk patients could be identified before treatment.

We retrospectively analysed a population-based cohort of SFT to describe treatment, outcome, prognostic factors and to further validate a previously published risk assessment tool (D-score) based on age, tumour size and mitotic index. Seventy-two patients diagnosed with SFT in the Central, North and Southern Denmark regions between 1979 and 2013 were included in the study.

For patients with localised disease at the time of diagnosis (n = 64) the 5 and 10 year overall survival was 86% (95% confidence interval 74-92) and 65% (95% confidence interval 50-78), respectively. Seventeen of 62 patients (27%) who were in remission after radical treatment developed recurrence with either local or distant disease. The 5 year recurrence-free survival was 83% (95% confidence interval 70-90) and the 10 year was 69% (95% confidence interval 53-81). The 5 year local recurrence-free survival was 96% (95% confidence interval 86-99) and the 10 year was 92% (95% confidence interval 76-96). The median time to both overall recurrence and local recurrence was 4.3 years. Metastatic or inoperable SFT had a poor prognosis with a median overall survival of 8.4 months (range 3.6-26.4) and a 5 year overall survival of 11% (95% confidence interval 2-30). A further validation of a risk assessment tool (D-score) confirmed that patients classified as high-risk had a significantly decreased overall survival, with a hazard ratio of 3.7 (95% confidence interval 1.1-12.3).

This study showed that our management and outcome were comparable with other published studies describing SFT and confirmed the value of the D-score as a risk assessment tool. Because of late recurrences, long-term (e.g. 10 years) follow-up for moderate- and high-risk patients is recommended.