The aim of this project was to investigate the diagnosis, treatment and consequences of local recurrence of soft tissue sarcoma (STS). It is based on patients reported to the Karolinska Hospital Sarcoma Register and the Scandinavian Sarcoma Group Register. Demographic and treatment data, based on 1613 adult patients reported to the Scandinavian Sarcoma Group Register by sarcoma centers in Norway, Sweden and Finland are presented. They all had STS of the extremities or trunk wall, and were diagnosed between 1986 and 1995. One third of the tumors were subcutaneous and two thirds deep-seated. The median size was 7 (1-35) cm and 75% were high grade. Metastases at presentation were diagnosed in 8% of the patients. Two thirds of the patients were referred to a sarcoma center before surgery. The preoperative morphologic diagnosis was made by fine-needle aspiration cytology in 72%. Among patients with final treatment for primary tumor at a sarcoma center (n = 1331), the surgical margins were wide or better in 76% of subcutaneous lesions, and in 58% of deep-seated lesions. Adjuvant radiotherapy has not generally been considered indicated after wide or compartmental excisions in Scandinavia. Overall, 23% of patients managed by surgery had adjuvant radiotherapy. Among patients with an intralesional or marginal excision, 44% had postoperative radiotherapy. Patients treated outside of sarcoma centers were seldom referred for radiotherapy. The crude local recurrence rate was 225/1331 (17%) among the patients with final treatment for primary tumor at a sarcoma center. The local recurrence rate after local surgery for high-malignant deep-seated STS was 103/391 (26%). The rate was 25/64 (39%) after an intralesional/marginal margin without postoperative radiotherapy versus 28/119 (24%) when radiotherapy was given. Fine-needle aspiration cytology (FNAC) was used to diagnose suspected local recurrences. 95 FNAC were performed in 86 patients from Karolinska Hospital. There were 47 local recurrences, of which 44 were diagnosed correctly by FNAC; one biopsy was inconclusive, and two lesions were incorrectly assessed as benign. 39 patients proved to have benign lesions in the scar examined cytologically on 50 occasions. None of the specimens was regarded as malignant, but in 4 cases FNAC was inconclusive. The inconclusive or false cytological diagnoses had no serious clinical consequences. Among 205 patients with local recurrence identified in the SSG Register 1987-1995, 169 patients were surgically treated. An intralesional or marginal margin was achieved in 110 of these patients, 59 of whom were also given radiotherapy. 54 of the 169 patients had a second local recurrence. The second local recurrence rate was 0.50 if the first local recurrence was treated using surgery with a marginal margin alone, compared to 0.28 if treated using either surgery with a marginal margin and radiotherapy, or a wide margin (p = 0.0008). In extremity STS, the amputation rate for local recurrences was 0.22, compared to 0.09 for primary tumors. The overall 5-year MFS was 0.72 (95% CI 0.68-0.76). High histopathological malignancy grade (Relative Risk 3.0; 95% CI 1.5-6.3) and an inadequate surgical margin (2.9; 95% CI 1.8-4.6) were independent risk factors for local recurrence. High histopathological malignancy grade and large tumor size (> 7 cm) were the most important risk factors for metastasis. Local recurrence was associated with an increased risk of metastasis (4.4; 95% CI 2.9-6.8), but an inadequate surgical margin was not a risk factor for metastasis (1.1; 95% CI 0.8-1.7). In conclusion, it is unlikely that local recurrence of STS is a major source of metastases. It nevertheless represents a costly, complicated and emotionally difficult problem. More radical surgical margins would improve the local recurrence rate, but this can hardly be achieved for center-operated patients without increasing the amputation rate. Instead, local control will improve by giving radiotherapy to all patients after marginal surgery, and to selected patients with wide margins. Radiotherapy is indicated especially after a previous open biopsy or when a local recurrence might lead to an amputation. Furthermore, radiotherapy seems indicated after local recurrence, regardless of margin or grade. The most effective way of reducing costs and detriment associated with local recurrence is to increase referral to sarcoma centers before biopsy or surgery as primary surgical margins would then improve.