By Dr. Wajeeha Anjum
Abstract:
Objective:
Spatially Fractionated Radiotherapy (SFRT) is known for its
highly potent immunomodulated response that contributes to
its highly effective outcomes. This makes SFRT one of the few
promising treatment options for conquering tumors, especially
in locally advance cases in palliative setting for symptomatic
controls. It used a novel and practical volumetric modulated arc
therapy (VMAT) planning approach for grid therapy
This study aims to report our early experiences of using
SFGRT for patients with various cancers in our hospital
Methods and Materials:
Dose is prescribed to 1.5-cm diameter spherical contours
placed throughout the gross tumor volume (GTV). Placement
of spheres is variable, but they must maintain at least a 2cm
(center to center) separation, and the edge of any sphere must
be at least 1 cm from any organ at risk (OAR). Three concentric
ring structures are used during optimization to confine the
highest doses to the center of the spheres and maximize dose
sparing between them. A dose of 20 GY is planned and
delivered to each sphere while keeping the dose to the rest of
CTV upto 10 GY. The end result is alternating regions of high
and low dose throughout the GTV and minimal dose to OARs.
High-intensity flattening filter-free (FFF) modes are used to
efficiently deliver the plans, and entire treatments typically
take around 35 minutes.
Results:
A total of 4 patients with various cancer types were treated
using SFGRT, with a median age of 47.5 years old males ,2
cases of sarcoma,1 case of mediatinal lymphoma and 1 case of
chordoma. The approach is illustrated with 4 examples treated
at our institution. Patient #1 had a 2203-cm3 mediastinal mass
and was prescribed 20 Gray (Gy) to 24 spherical regions within
the GTV. Patient #2 had a 3680-cm3 chordoma and was
prescribed 20 GY to spherical regions within the GTV .Patient
#3 was case of chondrosarcoma 1555cm3 of thigh and patient
#4 soft tissue sarcoma of gluteal region 2740cm3. All patients
received additional consolidative radiation approximately 1
week after the initial VMAT grid treatment. Each patient
experienced marked reduction in tumor size and symptomatic
relief without treatment-related complications. All cases were
palliative intent aimed at pain relief, bleeding control, or bulky
mass reduction.
Conclusions:
SFRT shows promising results in terms of tumor response,
especially for bulky tumor. Proper utilization of SFRT can
improve tumor response. Additionally, no significant toxicities
were found in all of our patients. As many centers offer VMAT
treatments, the approach is widely accessible and can be
readily implemented once appropriate patient selection and
delivery processes are established.