Preoperative radiation therapy with selective dose escalation to the margin at risk for retroperitoneal sarcoma

Abstract

BACKGROUND.Retroperitoneal sarcomas (RPSs) are rare tumors with poor survival rates due to difficult resectability and high local and distant recurrence rates.Preoperative radiation therapy appears to have dosimetric advantages to utilize the tumor as a tissue expander to limit exposure of small bowel to higher radiation doses. METHODS.Between June 1999 and December 2003, 16 consecutive patients with biopsy-proven RPS were treated with preoperative radiation with selective dose escalation. This included 45 grays (Gy) in 25 fractions to the entire tumor plus margin and a boost dose of 57.5 Gy to the volume predicted as high risk for positive surgical margins. Treatment toxicity and local control were evaluated prospectively as primary endpoints. The secondary goal was the theoretical calculation of future dose escalation and feasibility. Each patient underwent laparotomy. Tumor response was judged using computed tomography (CT) scan and by necrosis on final pathology. Theoretical treatment plans evaluated the potential for additional radiation dose escalation. RESULTS.All patients completed the radiation protocol. The most common acute side effects were nausea/vomiting, which affected 4 patients (25%), with only 1 patient requiring inpatient intravenous hydration. There was no severe late postoperative morbidity or mortality. Twelve tumors (75%) decreased in maximum dimension, with a median decrease of 9.4%. Fourteen of 16 patients (88%) underwent complete macroscopic resection. With a median follow-up of 28 months (range, 7-52 months), there were only 2 local recurrences. The actuarial 2-year local control rate was 80%. Theoretical treatment plans suggest that significant dose escalation (up to 80 Gy) may be possible. CONCLUSIONS.Preoperative radiation therapy with selective dose escalation to the margin at risk is tolerable and allows higher radiation dose to the volume judged to be at greatest risk for local tumor recurrence. Cancer 2006;107:371-9.

Radiotherapy and surgery—An indispensable duo in the treatment of retroperitoneal sarcoma

“…Others have confirmed these results. 19,55 These data compared favorably with historic controls and with series on ''surgery alone,'' especially considering the 25% recurrence rate and the high-grade histology in all tumors. 1 Jones et al published their patient series separately and reported 2-year OS and DFS rates of 88% and 80%, respectively.…”

“…First and foremost, the tumor often displaces the bowel out of the field of radiation and acts as a natural tissue expander, allowing treatment with a lower dose to the adjacent normal tissue. 19,53 Second, the often-present pseudocapsule of the Review Article tumor may thicken and become acellular, which eases resection and decreases the risk of local recurrence. Third, and probably most relevant, preoperative RT may sterilize the operative field against seeding of microscopic tumor emboli during surgical manipulation.…”

“…At the same time, a simultaneous integrated boost of 12.5 Gy was delivered to the ''margins at risk'' with the use of IMRT. 19 In an effort to reduce the bowel-related toxicity of RT, White et al used an abdominal tissue expander in association with preoperative EBRT. Two weeks after tissue expander insertion, EBRT at a dose of 45 to 50 Gy was commenced in 36 patients.…”

“…8,[10][11][12][13] After undergoing macroscopically complete surgery alone, local recurrences develop in 20% to 75% of patients, and these can occur even after 5 years of follow-up. 1,8,10,[14][15][16][17][18][19] The estimated survival rate at 5 years varies between 12% and 75%, 6,13,20,21 and the cause of death for these patients usually is local recurrence, which is in sharp contrast to outcomes for patients with sarcoma of the extremities. 8,22 There is much controversy concerning the role of radiotherapy (RT) in the treatment of RSTS.…”

“…[24][25][26][27] A major challenge for radiation oncologists is to combine the delivery of an effective radiation dose with an acceptable rate of radiation side effects. 19 The objective of this review was to define the exact role of RT in the management of RSTS.…”