(P 325) OUTCOMES AFTER MODERN THREE-DIMENSIONAL CONFORMAL RADIOTHERAPY AND INTENSITY MODULATED RADIOTHERAPY TO TREAT SARCOMAS ARISING IN THE HAND: A RETROSPECTIVE SERIES

Objective: Limb-salvage surgery and adjuvant radiotherapy to the hand-wrist complex pose challenges for surgeons and radiation therapists alike. Maintaining hand function is an important goal. The smaller soft tissue volumes around the hand-wrist complex may impact on the quality of radiation dose delivery and increase the risk of acute skin reaction. We explore the outcomes for patients treated with modern three-dimensional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) in a large sarcoma referral centre.

Methods: Adult patients with sarcoma of the hand-wrist area, treated with high dose radiotherapy, were retrospectively identified from sarcoma radiotherapy records dating back no further than 2001. Demographic data was collected on age, gender, site, histological subtype and grade, tumour size, and staging. Surgical data included procedure and resection margin status. Radiotherapy details included technique, dose-fractionation, timing of radiotherapy, treatment interruptions, acute and late effects. Outcome data was collected on local recurrence, distant metastases, and survival.

Results: 34 adult patients were treated between 2001-2023, median age 52 years(range 23-82), 52% male and 47% female. Tumours were centred on the hand(59%) or wrist(41%). 68% were newly diagnosed and 29% treated for local recurrence. 6% had metastases at the time of treatment. The most common subtypes were synovial sarcoma(29%), malignant peripheral nerve sheath tumour(12%), leiomyosarcoma(9%), myxofibrosarcoma(9%), myxoinflammatory fibroblastic sarcoma(9%), clear cell sarcoma(6%), spindle cell sarcoma(6%), and myoepithelioma(6%). Majority were grade 2 or 3(74%) and deep to fascia(85%). Median tumour size was 4.5cm(range 1.5-8cm). Surgery involved excision of finger rays or distal radius/ulna in 15% and 9%. Resection margins were R1 in 9% and R2 in 12%. R0 margins ranged from 1mm or less(44%) to wide. 9% had neo-adjuvant chemotherapy. Radiotherapy was pre-operative(24%) or post-operative(74%), and definitive in 1 patient. Treatment was with 3DCRT(79%), IMRT(18%) (example in Fig 1), and retreatment with brachytherapy in 1 case. Most frequent dose-fractionations were 60Gy/30 fractions(59%) and 50Gy/25 fractions(24%). Grade 3 skin reaction/swelling was described in 38%. 5 patients receiving 3DCRT had treatment interruption(6%) or did not complete the planned treatment(9%) due to acute skin reaction occurring after cumulative doses of 54Gy or more. All patients receiving IMRT completed treatment without interruption. Median follow up was 63 months(range 1-140). Outcomes at 5 and 10 years were: Overall survival 82% and 43.6% (Fig 2); Local control 79.3% and 72.7% (Fig 3); Distant metastases free survival 72.1% and 48.5% (Fig 4). Local recurrence was at median 16 months(range 8-71). Data on late effects and functional outcomes were not systematically collected in this retrospective series, but significant complications and functional loss were described in 6 patients(18%). Four of these had aggressive surgery with distal radial or ray resection.

Conclusion: This is the largest series of radiotherapy to sarcomas of the hand and wrist treated exclusively in the modern era of 3DCRT, including patients treated with IMRT, a technique not previously reported in the literature for this site specifically. The 5-year local control and survival outcomes in this cohort were comparable to published series, supporting a limb salvage approach with a combination of surgery and radiotherapy in this high-risk population where resection was marginal or incomplete in most cases. The reduced 10-year distant metastases free and overall survival rates potentially reflect the spectrum of late relapsing histological subtypes represented in this cohort. Radiotherapy delivery was challenging with a high incidence of significant acute toxicity reported, and treatment was interrupted or stopped before it could be completed in 15% of cases, all in the 3DCRT group. None of these patients developed a local recurrence however, raising a question about the potential for dose or dose intensity reduction that could be explored in future research. Local control was achieved at the cost of long-term functional loss in 18%, in line with functional outcomes reported in other series.