Effectiveness of interstitial brachytherapy in extremity sarcoma-treatment outcomes and current concepts

Radiation is an integral part of treatment of soft tissue sarcoma. Interstitial brachytherapy (ISBT) can deliver boost or radical dose sparing critical structures. Although this technology has been around the longest, it is seldom found in recent literature.

To report the outcomes of patients with soft tissue sarcoma who underwent ISBT after surgical resection.

We studied ISBT of extremity sarcoma in 60 patients aged between 3 and 77 years with a median age of 45 years and six patients belonging to the pediatric age group. Forty-two patients were males and 18 patients were females. Most common location was the thigh region (n = 27). The most common histological pattern was synovial sarcoma (n = 20), followed by extra-skeletal osteosarcoma [n = 10]. Utmost caution was taken to minimize the skin dose and the complications of ISBT. All patients underwent intraoperative brachytherapy catheter implantation. Brachytherapy consisted of high-dose rate (HDR) Iridium-192 interstitial implant with a range from 3 to 6 Gy per fraction with total dose ranging from 45 to 50 Gy. Fifty-five percent had combined external-beam radiation therapy (EBRT) and ISBT ranging between 4 and 10 sessions of ISBT. Maximum follow-up period was 72 months. The average depth of insertion of the implant was 5 mm below the skin. The patients were serially followed up and wound condition, skin toxicity, recurrence, and functional status of the limb were documented.

At final follow-up, there was 91% local control (55 patients) on the study population that received ISBT. All the surviving patients had functional limb. Three patients died due to chemotherapy-related neutropenic sepsis and disease progression. Most common complication encountered was skin problems. Fourteen patients had local irritation which gradually subsided; four patients had wound breakdown which was treated by debridement and secondary closure for two and by flap cover for other two patients. Overall survival rate was 86.4% with a median follow-up period of 33 months (2.75 years).

Excellent local control and long-term survival with acceptable skin toxicities and wound complications were observed in our case series of patients treated with ISBT and ISBT + EBRT using an Iridium 192-based HDR system.