Friday, April 10, 2009

Brachytherapy for Soft Tissue Sarcoma

JD presents a patient with a high grade un-differentiated sarcoma of the R bicep. Treated initially with surgery, positive margins. Treated postoperatively to 70 Gy at that time. Recurred twice more with positive margins on resection each time (positive margin is at the neurovascular bundle).

Brought to resection again, this time with very close margins (2mm). Catheters were placed for LDR treatment.

IJROBP 2001;49:1033- ABS recommendations for brachytherapy in sarcoma. For recurrences LDR +/- EBRT. Positive margins reccomend LDR + EBRT. High Grade negative margins reccomend LDR +/- EBRT. Low Grade negative margins - consider observation of possibly LDR or EBRT.

Pisters JCO 1996 - Surgery +/- LDR for STS. n=164. 30% were recurrent, 40% were low grade, 15% had positive margins. PTV = tumor bed + 2cm. Catheters 1cm separation. 42-45Gy over 4-6 days. Loaded POD 5 or 6. Ir192 wires. 5year local control 82% vs 69%, p=0.04. Most recurrences occurs within 3-4 years. OS no difference largely due to the ability to salvage with amputation.

High Grade local control was 89% LDR vs 66% (SS), Low Grade 64% LDR vs 74% (NS). Wound complications were much lower is catheters were loaded after day 5 (and mid trial, due to this observation, they began loading later).

NL comments that this approach is not currently in use a MSKCC - rather pre or post op EBRT is used with LDR is selected scenarios.

Yang JCO 1998 - EBRT trail n=140, 45 Gy EBRT with 18 Gy LDR boost, concurrent doxorubicin, ifosphamide if high grade. Local control improved in both high grade and low grade. (10yr local control HG 100% vs 80% SS, LG 96% vs 67% SS). OS no difference.

Note that doxorubicin is not used with concurrent RT due to toxicity.

Multiple retrospective series report LC of 90% with EBRT and LDR boost.

Delaney IJROBP 2007 - retrospective of EBRT for recurrent (previously treated) STS - showed 80% LC with doses >64Gy.

Sindelar Arch Surg 1993;128:402 Retroperitoneal Sarcoma, n=37. randomized to postoperative 54Gy EBRT or 35Gy EBRT + 20Gy IORT. Infield local recurrence improved p<0.05, however all local recurrence NS. Increase GI toxicity in the EBRT arm, vs increased peripheral neuropathy in the IORT arm.

Retrospective series show 70-90% local control with HDR.

Our reccomendations for recurrent disease is highly individualized. Often IMRT is used in combination with either LDR or HDR optimization. Often times preoperative EBRT is given, then if positive or close margins are expected, catheters are placed intraoperatively, and loaded after POD 5 if final path shows concern.

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