NcXHF

DICKIE, HAAS, AND O’SULLIVAN
Adjuvant Radiation for Soft Tissue Sarcomas
Colleen I. Dickie, MSc, Rick Haas, MD, PhD, and Brian O’Sullivan, MD, FRCPC
OVERVIEW
Over recent decades, limb-preservation surgery in combination with radiotherapy achieves local control rates exceeding 90% for
extremity soft tissue sarcoma (STS). Local control is not as successful for retroperitoneal sarcoma (approximately 60%) despite
aggressive surgical approaches including en bloc resection of uninvolved adjacent organs combined with intensity modulated radiotherapy
(IMRT). This review will discuss the indications for adjuvant radiation therapy (RT) for primary presentation of soft tissue
sarcoma: “What,” referring to the type and manner of planning and delivery of RT; “When,” referring to the timing and scheduling of
RT; and “Why,” referring to the rationale for the use of RT will be addressed. From a practical stand point, this Educational Chapter
on “adjuvant RT” will focus on pre- and postoperative RT in the context of gross total resection for extremity and retroperitoneal soft
tissue sarcoma, the two most frequent paradigms for the use of adjuvant RT.
Various types of RT can be used in the treatment of STS
and require attention to the application of appropriate
principles for their implementation. Especially important are
issues surrounding the choice of target volumes, the treatment
of normal anatomy termed “organs at risk,” and processes
to ensure reliability in treatment delivery. Most
experience in adjuvant RT of STS is based on external beam
radiotherapy (EBRT). Nevertheless, other modalities exist
including brachytherapy, intraoperative RT, and hadrons
(i.e., protons and carbon ions).
TYPES AND METHODS OF RADIOTHERAPY
DELIVERY: THE “WHAT” COMPONENT
Intensity Modulated Radiotherapy
Target coverage and protection of normal tissues appear to
be superior for IMRT compared with traditional techniques
in extremity STS (ESTS). 1,2 A recent retrospective review
spanning noncoincident treatment time periods compared
surgery combined with either IMRT (165 patients) or conventional
EBRT (154 patients). Allowing for known limitations
associated with studies involving treatments
deployed over different eras, IMRT demonstrated signifıcantly
reduced local recurrence (LR) for primary ESTS
(7.6% LR for IMRT vs. 15.1% LR for conventional RT; p
0.02). 3
Two recently completed prospective phase II trials, from
Princess Margaret (NCT00188175) and the Radiation
Therapy Oncology Group (RTOG 0630; NCT00589121),
investigated if preoperative image-guided radiotherapy
(IGRT) using conformal RT/IMRT can reduce RT related
morbidities. The characteristics of the Princess Margaret
Hospital (PMH) and RTOG 0630 trials are not identical in
several ways and are contrasted (Table 1). 4,5
The PMH trial showed less wound healing complication
rates (30.5%) in lower extremity compared with the 43% risk
in the previous Canadian Sarcoma Group NCIC SR2 trial
that only used two-dimensional and three-dimensional RT. 6
The need for tissue transfer, RT chronic morbidities, and
subsequent secondary operations for wound complications
was reduced while maintaining good function and local control
(93.2%). The recently published results of the RTOG-
0630 trial reported a signifıcant reduction of late toxicities
compared with the NCIC-SR2 trial (10.5% vs. 37% in SR2),
which is very similar to the IGRT PMH trial. Importantly,
both trials defıned the clinical target volume (CTV) differently
(longitudinal margin of 3 cm from the gross tumor for
high-grade lesions and 2 cm for low-grade lesions vs. 4 cm
longitudinal margins in the PMH trial). Potentially, the reduction
in CTV margins of this degree could explain the improvement
in limb function with comparable local control,
although, an alternative possibility is the reduction in normal
tissues receiving the target dose in all dimensions that is
shared by both studies.
Brachytherapy
Brachytherapy has several theoretical advantages. With appropriate
selection, local dose intensifıcation to target structures
with surrounding normal tissue protection is feasible.
The treatment time is shorter, theoretically limiting tumor
From the Department of Radiation Oncology, Princess Margaret Cancer Centre, Toronto, ON, Canada; Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada; Department
of Radiotherapy, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, Netherlands.
Disclosures of potential conflicts of interest are found at the end of this article.
Corresponding author: Brian O’Sullivan, MD, FRCPC, Princess Margaret Hospital, University of Toronto, Rm 5-624, 610 University Ave., Toronto, ON M5G 2M9, Canada;
email: brian.o’sullivan@rmp.uhn.on.ca.
© 2015 by American Society of Clinical Oncology.
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