Retroperitoneal Sarcoma (RPS) - PowerPoint Presentation

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Retroperitoneal Sarcoma (RPS) High Risk Gross Tumor Volume Boost (HR GTV Boost) Contour Delineation Agreement among RTOG Sarcoma Radiation and Surgical Oncologists Elizabeth H Baldini MD, MPHDana-Farber Cancer Institute/Brigham and Women’s Hospital

CTOS

October 16, 2014

Contributing Authors

E Baldini, C RautD Wang, R Abrams, K MillikanK Salerno, J KaneC Deville, G KarakousisI Petersen, M KendrickT DeLaney, Y Chen, J MullenW Bosch

Dana-Farber/Brigham & Women’sRush University Medical CenterRoswell Park Cancer InstituteUniversity of PennsylvaniaMayo ClinicMassachusetts General HospitalWashington University

Supported by grants U10CA21661, U10CA180868, U10CA180822

,

U10CA37422

, U24CA180803 from the National Cancer Institute

Background

Only proven curative intent treatment modality for RPS is surgeryRole of pre-op RT has not been proven and is the subject of a randomized trial: EORTC STRASS 62092In the meantime, many multi-disciplinary teams employ pre-op RT for RPS and consensus guidelines have been developed for delineation of RT target volumes*

*CTOS, New York, 2013

Background

Further, there is interest in delivering a “boost” dose of RT to high risk areas of the tumor volume judged to be at risk for positive margins following resectionThis is being tested in a multi-center Phase I/II trial among several US NRG institutions (PI: DeLaney)

Gross Tumor

Volume(GTV)

High Risk Boost Volume

Radiation Target Volume Definitions

GTV: Gross Tumor VolumeCTV: Clinical Target Volume- GTV plus adjacent areas of potential microscopic diseaseHigh Risk GTV (HR GTV): Area of GTV judged to be at high risk of positive margins after resection

GTV: red

CTV: yellow

GTV: red

HR GTV: pink

Background

Target VolumeKappa AgreementRPS1RPS2Gross Tumor Volume(GTV)0.84 Almost Perfect0.92 Almost PerfectClinical Target Volume(CTV)0.79 Substantial0.86 Almost PerfectHR Boost Volume0.50 Moderate0.57 Moderate

HR Boost Volume contour agreement was suboptimal More clarification of this boost target volume is needed Basis of the current project

Variability of RPS target volume contour delineation among Sarcoma Radiation Oncologists has recently been assessed**

**ASTRO, San Francisco, 2014

Purpose

To evaluate the variability in HR GTV Boost target volume delineation among sarcoma radiation and surgical oncology teams

Methods

Radiation planning CT scans for 3 cases of RPS were distributed to 7 radiation and surgical oncology teams

GTV (gross tumor volume) and organ contours were provided

Teams were asked to contour HR GTV Boost volumes for each case

HR GTV Boost Contour Instructions

Area considered to be at high risk for positive margins following resectionGenerally areas of tumor located along posterior RP musculature, ipsilateral pre-vertebral space, major vessels, or organs the surgeon would leave in situContour 1.5 cm thick 

High Risk Boost Volume

GTV

Methods: Analysis of Contour Agreement

Simultaneous truth and performance level estimation (STAPLE) algorithm* Kappa statistics (yield values from -1 to +1)Kappa = -1 : complete disagreementKappa = +1 : complete agreementDescriptive categories for interpretation of strength** Kappa < 0 is poor 0.00 - 0.20 is slight 0.21 - 0.40 is fair 0.41 - 0.60 is moderate 0.61 - 0.80 is substantial 0.81 - 1.00 is almost perfect agreement

*Warfield, IEEE Transactions on Medical Imaging 2004;23:903

** Landis, Biometrics 1977;33:159

Results

Each case was contoured by 7 radiation and surgical oncology teams

First case: RPS 1

De-differentiated (DD) liposarcoma (LPS) of right upper quadrant

Second case: RPS 2

Leiomyosarcoma (LMS) of left upper quadrant

Third case: RPS 3

DD LPS of left lower quadrant with extension through inguinal canal into upper scrotum

Results HR GTV Boost Volume Contour Agreement

Kappa AgreementRPS 1: DD LPS right upper quadrant0.66 ModerateRPS 2: LMS left upper quadrant0.61 ModerateRPS 3: DD LPS left lower quadrant0.52 Moderate

Slightly better agreement than prior consensus project (0.50, 0.57)

Contour agreement for all cases was only moderate

HR GTV: Very Good Agreement

RPS 2: LUQ LMS

Very good contour agreement laterally along chest wall and medially along ipsilat para-vertebral space and aorta

Red: GTV

Other colors: HR GTV volumes

HR GTV: Marginal Agreement

Red: GTV

Other colors: HR GTV volumes

RPS 3: LLQ DD LPS

Marginal

contour agreement medially along bladder and

anteriorly

along anterior abdominal wall

HR GTV: Marginal Agreement

Red: GTVOther colors: HR GTV volumes

RPS 1:RUQ DD LPSMarginal agreement along liver 4 contours include entire liver surface in contact with tumor, 3 contours exclude liver

Conclusion

Overall agreement for HR GTV boost volumes was moderate

Contour agreement was best:

Postero

-laterally, abutting chest wall

Medially, abutting RP musculature, ipsilateral para-vertebral space, great vessels

Contour agreement most variable:

Abutting organs such as liver and bladder

Discrepancies are explained by differing surgical opinions regarding partial organ resections for these cases

Highlights extreme importance of collaboration between radiation and surgical oncologist for each patient

Future Directions

Further discussion among sarcoma radiation and surgical oncologists is needed to reach improved consensus

An atlas with detailed examples of HR GTV volumes may be an effective educational tool