Treatment Guidelines for Pre-operative Radiation Therapy

for Retroperitoneal Sarcoma: Preliminary Consensus of an

International Expert Panel

EH Baldini, D Wang, CN Catton, DJ Indelicato, DG Kirsch, C Deville, C Le Pechoux, R Haas, IA Petersen, K May, D Roberge, BA Guadagnolo,

B O'Sullivan, R Abrams, TF DeLaney

None of the authors have disclosures

Background

• The role of RT for extremity soft tissue sarcoma is well established

• However, the role of RT for retroperitoneal sarcoma (RPS) is unproven

EORTC 62092-22092 (STRASS Trial)

Ongoing, results are eagerly anticipated

Background

• In the meantime, many centers recommend Pre-op RT for RPS after multidisciplinary discussion

• But, there are no RT guidelines for this approach

Purpose

• To define radiation treatment guidelines for Pre-operative RT for RPS

RT Treatment Nomenclature

• GTV: Gross Tumor Volume

• CTV: Clinical Target Volume–Expansion of GTV to include areas at risk for

harboring potential microscopic disease

• PTV: Planning Target Volume–Expansion of CTV to account for daily patient

set-up inaccuracies and/or patient movement

• Treatment Field Borders–Extend beyond the PTV by about 7mm to

deliver full dose to PTV

Extremity Soft Tissue Sarcoma RT Treatment Guidelines*

CTV • GTV + 4 cm

proximal/distal, • 1.5 cm radial• Edit CTV at bone

PTV• CTV + 5-10mm per

institutional standard

*Haas, IJROBP 84:572; 2012

GTV: redCTV: greenPTV: orange

4 cm

1.5 cm

GTV, CTV, PTV

Note the CTV is edited at the bone interface

GTV CTV Expansions Vary by Tumor

Tumor GTV CTV Expansion

Lymphoma 0 mm

Prostate Cancer 5-7 mm

Lung Cancer 7 mm

Glioblastoma Multiforme 2 cm beyond edema

Extremity STS 1.5 cm radial4 cm proximal/distal

Retroperitoneal Sarcoma ?

Methods

• An expert panel of 15 academic radiation oncologists who specialize in sarcoma was convened

• Panel members reached consensus recommendations following several meetings, conference calls and email correspondence

Expert Panel: US Institutions (10)• Dana-Farber/Brigham & Women’s Hospital• Massachusetts General Hospital• Medical College of Wisconsin• University of Florida, Jacksonville• Duke University• University of Pennsylvania• Mayo Clinic• Roswell Park Cancer Institute• MD Anderson Cancer Center• Rush University

Expert Panel: European and Canadian Institutions (4)

Canada–Princess Margaret Cancer Centre–McGill University Health Centre

France– Institut Gustave Roussy

Netherlands–Netherlands Cancer Institute

Results

Consensus Recommendations

Essential Collaboration between Surgeon + Radiation Oncologist

Discuss resection margins of concern

Discuss potential resection of kidney, liver– If nephrectomy is planned:»Adequate contra-lateral renal function

should be documented»Minimize dose to contra-lateral kidney

– If partial liver resection is planned:»Minimize dose to remaining liver

Radiation Simulation

• Oral and IV contrast is optional

• Assessment of 4D motion (4D CT)–Strongly recommended for tumors above

iliac crest to define GTV4D

• Contour GTV on the planning CT –Register planning CT with diagnostic CT or

MR T1 contrast images if necessary

CTV DefinitionExpand GTV symmetrically by 1.5 cm

Edit CTV:• Bone: 0 mm• Bowel and Air Cavity: 5 mm• Renal and Hepatic interfaces: 2 mm• Skin Surface: 3-5 mm• If tumor extends through inguinal canal, add

3 cm distally (as per extremity STS)• If 4D CT is not performed, larger expansions

are necessary for upper abdominal tumors

PTV Definition

• Expand CTV by 5mm – If frequent volumetric soft tissue imaging

will be performed to confirm set-up accuracy (i.e. cone beam CT)

• Expand CTV by 9-12 mm – If no volumetric imaging is performed to

confirm set-up

Dose

5040 cGy

180 cGy fractions

5 ½ weeks

RPS Contours

GTVCTVPTV

RPS IMRT Graphic Plan

Iso-dose Levels

100% 70%95% 50%80% 30%

Dose-Painting Radiation Boost to High Risk Margins

CONCEPT:• Deliver boost dose

of RT to areas of tumor at risk for positive margins after resection

• Along posterior abdominal wall, pre-vertebral space, major vessels

High Risk Boost Volume

GTV

Dose-Painting Radiation Boost to High Risk Margins

• Efficacy is unproven

• Technique is under investigation

• May be considered, particularly on protocol–DeLaney Phase I/II Multi-Center Dose-

Painting Boost, Dose-Escalation Trial

Organ at Risk (OAR) Constraints

ORGAN CONSTRAINTLiver Mean Dose < 26 Gy

Stomach and Duodenum V45<100%, V50<50%, Max 56 Gy

Kidney: if one will be resected V18 < 15% remaining kidney

Kidney: if both will remain Mean dose < 15 Gy, V18 < 50%

Spinal Cord Max Dose 50 Gy

Small & Large Bowel (Bowel Bag) V45 < 195 cc

Rectum V50 < 50%

Testicles V3 < 50%, Max Dose < 18 Gy

Ovary Max Dose < 3 Gy

Femoral Head Max Dose < 50 Gy, V40 < 64%

Treatment Technique

• Intensity modulated radiation therapy (IMRT) preferred unless OAR constraints can be met with 3D-conformal technique

Conclusion

• Consensus guidelines were achieved and are recommended for use

–To establish uniformity of treatment

–Aid future efficacy and toxicity assessment

Thank You

• Tom DeLaney• Dian Wang• Charles Catton• Danny Indelicato• David Kirsch• Curt Deville• Cecile Le Pechoux

• Rick Haas• Ivy Petersen• Kilian May• David Roberge• Ashleigh Guadagnolo• Brian O’Sullivan• Ross Abrams