['Administration of preoperative radiotherapy for extremity soft tissue sarcoma improves local control, while allowing for a more conservative surgical resection. During radiation treatment tumor size typically decreases or remains constant. In a subset of patients, however, a size increase in the tumor occurs. Our goal was to investigate the prognosis of patients who had a size increase of at least 20% over the course of preoperative radiotherapy versus those who did not.', 'This retrospective study evaluated 70 patients treated for localized primary STS of the extremities between January 2000 and December 2008. Kaplan-Meier curves for disease-specific and metastasis-free survival were calculated for both groups.', "Sixty-one patients had stable or decrease local tumor size following preoperative radiotherapy and nine patients had an increase of at least 20% in tumor size. There were no statistically significant differences found in disease-specific survival and metastasis-free survival (Gray's test, P = 0.93 and P = 0.68, respectively) among the two groups."] Does tumor size increase following preoperative radiation of soft tissue sarcomas affect prognosis?