Trial Information

Phase II Clinical Trial: The Effect of Bone Marrow-sparing Intensity-Modulated Radiotherapy (BMS-IMRT) on Reduction Acute Hematologic Toxicity in Gastric and Rectal Cancer Patients Treated With Concurrent Chemotherapy and IMRT

1、Simulation All patients underwent computed tomography (CT) simulation in the supine
position for gastric cancer patients and The CT scan was obtained from the T4 vertebral body
to L5 cm. Oral contrast and intravenous contrast were administered prior to the CT scan.

All patients underwent computed tomography (CT) simulation in the prone position for rectal
cancer patients with a full bladder and using a belly board to minimize exposure of the
small bowel. Oral contrast and intravenous contrast were administered prior to the CT scan.
A radio-opaque marker was placed at the anal margin. The superior and inferior limits of the
acquired transaxial data (set by the topogram) were the iliac crests and 5 cm inferior to
the anal marker, respectively. Intravenous contrast were administered prior to the CT scan.

2.Radiotherapy and chemotherapy For gastric cancer patients after surgery and
chemotherapy,the 4500 cGy of radiation was delivered in 25 fractions, five days per week,
to the tumor bed, to the regional nodes, and 2 cm beyond the proximal and distal margins of
resection. The tumor bed was defined by preoperative computed tomographic (CT) imaging,
barium roentgenography, and in some instances, surgical clips. Perigastric, celiac,
local paraaortic, splenic, hepatoduodenal or hepatic-portal, and pancreaticoduodenal lymph
nodes were included in the radiation fields. In patients with tumors of the gastroesophageal
junction, paracardial and paraesophageal lymph nodes were included in the radiation fields.
Concurrent chemotherapy regimen is monotherapy with capecitabine 1600mg∙m2 twice a day
(b.i.d.).

For rectal cancer patients before surgery, The rectum was not opacified with barium in order
to avoid contour artifacts. The gross tumor volume (GTV) was generated with the CT scan, MR
scan and endoscopic ultrasonography results. Only a clinical target volume (CTV) was
delineated, encompassing the entire mesorectum, Pararectal nodes were also included,
together with the presacral and promontory nodes (limit to L5-S1 interspace ), and the
internal iliac nodes up to the venous bifurcation. External iliac nodes were not included as
they have not been a site for recurrence in our experience. On the contrary, internal
pudendal nodes were included in the CTV. Organs at risk were also contoured: bladder (with
intravenous contrast), small bowel (with oral contrast) and femoral heads. The small bowel
was contoured on all CT slices where it could be visualized, which was highly variable among
patients. IMRT is given with 5000 cGy in 25 fractions (5 weeks). Concurrent chemotherapy
consists of oxaliplatin (50 mg/m2 ) intravenously over 2 h on days 1, 8, 15, 22 and 29, and
capecitabine (825 mg/m2 twice day) was given orally on each day of radiation.

3. Active bone marrow definition All the patient was scanned in the supine position on a 1.5
T MR scanner. For gastric cancer patients, the images were obtained from the T8 to L4 for
gastric cancer patients. For rectal cancer patients, the images were obtained from the L3-4
interspace to below the ischial tuberosities for rectal cancer patients.

The MR images were subsequently fused with the planning CT scan using commercially available
image fusion software. The interactive mode of the fusion software was used whereby the user
manually translates and rotates the MR scan to produce the best visual overlay of the two
image sets. A mutual information algorithm was then used to perform a fine adjustment. The
CT and MR images (resliced along the planes of the CT scan) were subsequently displayed
side-by-side. BM regions on the T1-weighted images that showed a signal intensity equal to
or slightly higher than that of muscle were contoured as active BM. The range of active BM
was 3cm beyond the upper limit of PTV and 3cm below the lower limit of PTV.