IMRT, Designed with Evidence-Based Bone Avoidance Objectives, Reduces the risk of

Bone Fracture in the management of Extremity Soft Tissue Sarcoma

Colleen Dickie MSc, MRT(T)(MR)Assistant Professor, University of Toronto

UHNPrincess Margaret Cancer Center

Acknowledgements

Anthony M. Griffin, MScAmy Parent, MRT(T), BSc, CMDMichael B. Sharpe, PhDPeter C. Ferguson, MD, FRCSCJay S. Wunder, MD, FRCSCPeter Chung, MD, FRCPCCharles N. Catton, MD, FRCPCBrian O’Sullivan, MD, FRCPC

Princess Margaret Cancer Center

Background

Holt et al. Fractures following RT and Limb-Salvage Surgery for LE-STS: JBJS 2005

Sternheim et al. Internal fixation …high rate of failure: Bone Joint J 2013;95-B:1144–8.

• Severe morbidity Review of 22 pts with internal fixation for fracture

Complications in 86% (82% non union at 12 mos) 13 pts underwent 24 revision operations

• 364 LE-STS EBRT Females, > 55 yrs, thigh tumor locationPeriosteal stripping High (60-66 Gy – 10 %) vs. Low (50 Gy -2%)Overall – 6.3 % crude riskMedian F/U = 58 mos

Background• 1989 - 2004• Lack of 3D info• 21 pts 24 fractures: 53 control

Matched on gender, tumour size /

location, age, beam arrangement, RT

timing / RT dose

• Fracture Risk reduced if: V40 kept below 64% Mean bone dose < 37 Gy Max bone dose < 59 Gy

Dickie et al. Bone Fractures following EBRT… IJROBP 2009 Nov 15;75(4):1119-24.

Objective

• To evaluate the potential for IMRT to reduce the risk of bone fractures: Lower extremity soft tissue sarcoma (LE-STS) Combined modality local treatment

• Evidence based Bone Avoidance Objectives (BAO) V40 kept below 64% Mean bone dose < 37 Gy Max bone dose < 59 Gy

Dickie et al. Bone Fractures following EBRT… IJROBP 2009 Nov 15;75(4):1119-24.

Methods / Materials• Study timeframe: 2005 – 2011

• 230 plans employed BAO from our previous study 176 lower extremity 54 upper extremity

• Study confined to weight bearing bones to minimize reporting bias i.e. Removed upper extremity cases (176 LE-STS)

• All patients: Surgery combined with RT 155 received preop (50 Gy) 21 received postop (60 – 66 Gy) 2 Gy per fraction daily

Methods / Materials• 4 patients re-irradiated for in field recurrent disease

44 Gy / 40 fractions BID 6 hours apart

• 5 patients re-irradiated for recurrent disease at edge 50 Gy in 25 fractions

• We evaluated: Mean bone dose Max bone dose Volume of Bone receiving > 40 Gy (V40) Mean dose to the clinical target volume (CTV dose)

Results

• Target Coverage Criteria 100 %• BAO achieved: 96 % preop, 72 % postop RT plans• 4 patients experienced a bone fracture (2.2 %)

All preop 50 Gy / 25 f, 1 further 44 Gy / 40 f 3 males, 1 female

• Mean F/U= 47 mos

Dose (Gy) Preoperative RT Postoperative RT Re-irradiation

Mean Bone 25.9 + 9 31.4 + 13 24.4 + 11

Max Bone 49.1 + 4 55.4 + 13 48.3 + 13

V40 (%) 32.3 % 37.3 % 27.5 %

Mean CTV 50.6 + 1 64.9 + 2 51.1 + 6

9

First Fracture Case• 46 yr old Male - Crane operator• Myxoid Liposarcoma Rt Calf• Preop RT & Sx 2007• 15 mos post Tx spiral fracture• Trauma by metal crane ring

within RT volume• > 58 Gy coincided with fracture

site• Treated conservatively

20082011

High dose >58Gy

2007

CTV mean = 50.9 GyBone mean = 30.6 GyBone max = 58.7 GyBone V40 = 37 %PASSED

10

Second Fracture CaseOriginal

Retreat

10 cm

• UPS RT Thigh

• 55 yr Male

• Preop RT 2008

• Sx 2009

• In- field recurrence 2010

• Retreatment Second RT

course: IMRT 44 Gy / 40

11

Second Fracture Case• Proximal femur fracture

2012- fall at home

• 41 mos post Tx

• IM nail / Iliac crest bone

graft

• 6 mos no healing

• Cemented proximal femur

tumor prosthesis 2013

2012

2013

1st PlanCTV = 51.7 GyBone mean = 35.5 GyBone max = 49.8 GyBone V40 = 31 %

BID planCTV = 40 GyBone mean = 15 GyBone max = 35 GyBone V40 = 1 %

Third Fracture Case

• 63 yr old Male• Fibrosarcoma RT Thigh• Preop RT & Sx 2007• Disease > 60%

circumferential• Fall - Fracture May

2008• IM nail inserted

GTV

High RT dose

FAILEDCTV mean 52.7 GyBone mean 41.4 GyBone max 52.9 GyBone V40 75.9 %

13

Fourth Fracture Case

• UPS RT thigh

• 57 yr Female

• Preop RT

• Disease > 60%

Circumferential

• 19 mos post Tx- pain

• Undisplaced transverse

fracture

• IM nailGTVCTV mean = 51.9 Gy

Bone mean = 26.1 GyBone max = 53.7 GyBone V40 = 39 %PASSED

Conclusions• Risk of fracture using BAOs is lower than previously reported

(2.2 % vs. 6.3 %)• Preferential use of preoperative RT

adverse RT morbidities RT volumes and doses

• Bone objectives are practical and beneficial• Bone sparing techniques should be employed for:

Circumferential disease In re-irradiation settings For women > 55 yrs

AcknowledgementsAnthony M. Griffin, MSc

Amy Parent, BSc, MRT(T)Michael B. Sharpe, PhD

Peter C. Ferguson, MD, FRCSCJay S. Wunder, MD, FRCSCRobert S. Bell, MD, FRCSCPeter Chung, MD, FRCPC

Charles N. Catton, MD, FRCPCBrian O’Sullivan, MD, FRCPC

Princess Margaret Cancer Center