Posters— Radiation Oncology

PATTERN OF LOCAL RECURRENCE AFTER CONSERVATIVE SURGERY AND RADIOTHERAPY FOR SOFT TISSUE SARCOMA

Cleator SJ, Cottrill C, Harmer CL (Sarcoma Unit, Royal Marsden Hospital NHS Trust, London SW3 6JJ)

Purpose: Over the past two decades our centre has adopted a policy of conservative surgery followed by adjuvant radical-dose radiotherapy for all medium- and high-grade soft tissue sarcomas. From the patients treated in this manner at the Royal Marsden Hospital over the last 15 years we analyzed 17 who had relapsed locally. We discuss technical factors that may have contributed to local relapse in some cases and the geographical relationship between sites of recurrence and the phase 1 and 2 radiotherapy volumes.

Patients and methods: We examined those cases recorded on our soft tissue sarcoma database between January 1986 and September 1999 who had recurred locally following surgery and radical post operative radiotherapy. We excluded patients with residual macroscopic disease following surgery and any patients with metastatic disease at presentation. We recorded details relating to original tumour stage, histological type, grade and surgical margins. The cohort included 8 patients with T1 (47%) and 9 patients with T2 tumours (53%). The tumours were grade 1, 2 and 3 in 2 (12%), 6 (35 %) and 9 (53%) number of cases respectively. The majority of patients were treated with a phase I volume corresponding to the entire muscle compartment which received 50 Gy in 25 fractions over 5 weeks. The phase II was a reduced volume corresponding to the tumour bed and received 10 Gy in 5 fractions during the sixth week of treatment. Four of the patients were treated according to a hyperfractionated regimen consisting of 72 Gy in 60 fractions twice daily over 6 weeks with volume reduction after 60 Gy.

Results: Mean time to local recurrence was 26 months. Four (23%) patients recurred within the phase I volume, 9 (53%) recurred within the phase II volume and 3 (18%) outside the irradiated volume. One recurrence was marginal. Eight patients who relapsed had positive surgical excision margins originally. In 6 patients there had been deviations from our radiotherapy protocol, usually unavoidable, which may have accounted for treatment failure; these included all three out of field recurrences. Of the 11 patients for whom it was possible to adhere strictly to protocol, 2 recurred in the phase I volume and 9 in the phase II volume. With a mean follow-up time since completion of radiotherapy of 63 months, 7 patients have died, and of these 6 were disease- related.

Conclusion: A dose greater than 60Gy may be necessary despite initial complete surgical resection. Prospective, multi-centre data collection and ideally a randomized trial are required to formulate an improved treatment policy.

Keywords: sarcoma, post-operative radiotherapy, recurrence, conservative surgery.