Risk of secondary cancers from scattered radiation during intensity-modulated radiotherapies for hepatocellular carcinoma.

PURPOSE: To evaluate and compare the risks of secondary cancers from therapeutic doses received by patients with hepatocellular carcinoma (HCC) during intensity-modulated radiotherapy (IMRT), volumetric arc therapy (VMAT), and tomotherapy (TOMO). METHODS: Treatments for five patients with hepatocellular carcinoma (HCC) were planned using IMRT, VMAT, and TOMO. Based on the Biological Effects of Ionizing Radiation VII method, the excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) were evaluated from therapeutic doses, which were measured using radiophotoluminescence glass dosimeters (RPLGDs) for each organ inside a humanoid phantom. RESULTS: The average organ equivalent doses (OEDs) of 5 patients were measured as 0.23, 1.18, 0.91, 0.95, 0.97, 0.24, and 0.20 Gy for the thyroid, lung, stomach, liver, small intestine, prostate (or ovary), and rectum, respectively. From the OED measurements, LAR incidence were calculated as 83, 46, 22, 30, 2 and 6 per 10(4) person for the lung, stomach, normal liver, small intestine, prostate (or ovary), and rectum. CONCLUSIONS: We estimated the secondary cancer risks at various organs for patients with HCC who received different treatment modalities. We found that HCC treatment is associated with a high secondary cancer risk in the lung and stomach.

Risk of second cancer from scattered radiation of intensity-modulated radiotherapies with lung cancer.

PURPOSE: To compare the risk of secondary cancer from scattered and leakage doses following intensity-modulated radiotherapy (IMRT), volumetric arc therapy (VMAT) and tomotherapy (TOMO) in patients with lung cancer. METHODS: IMRT, VMAT and TOMO were planned for five lung cancer patients. Organ equivalent doses (OEDs) are estimated from the measured corresponding secondary doses during irradiation at various points 20 to 80 cm from the iso-center by using radio-photoluminescence glass dosimeter (RPLGD). RESULTS: The secondary dose per Gy from IMRT, VMAT and TOMO for lung cancer, measured 20 to 80 cm from the iso-center, are 0.02~2.03, 0.03~1.35 and 0.04~0.46 cGy, respectively. The mean values of relative OED of secondary dose of VMAT and TOMO, which is normalized by IMRT, ranged between 88.63% and 41.59% revealing 88.63% and 41.59% for thyroid, 82.33% and 41.85% for pancreas, 77.97% and 49.41% for bowel, 73.42% and 72.55% for rectum, 74.16% and 81.51% for prostate. The secondary dose and OED from TOMO became similar to those from IMRT and VMAT as the distance from the field edge increased. CONCLUSIONS: OED based estimation suggests that the secondary cancer risk from TOMO is less than or comparable to the risks from conventional IMRT and VMAT.

The prognostic effect of VEGF expression in squamous cell carcinoma of the cervix treated with radiation therapy alone.

We investigated the relationship between vascular endothelial growth factor (VEGF) expression and clinical outcome in squamous cell carcinoma of the cervix treated with radiotherapy alone. The immunohistochemical study was performed for forty-two paraffin embedded specimens with anti-VEGF mouse monoclonal antibody. Staining was defined as positive for VEGF when more than 10% of the tumor cells were stained from 500 cells counted. Positive VEGF expression was observed in twenty-one among forty-two patients. VEGF expression according to stage (p=0.101), lymph node status (p=0.621), parametrial invasion (p=0.268), and age (p=0.5) revealed no significant difference. But the VEGF expression was significantly higher in tumors larger than 4 cm (p=0.031). Five year survival rates according to VEGF expression status were 89% for VEGF negative group and 47% for VEGF positive group (p=0.02). FIGO stage (p=0.007), tumor size (p=0.025) and the duration of external beam radiation therapy (p=0.006) were also significant prognostic factors for overall survival. We suggest that VEGF expression may be a prognotic factor of the cervix cancer patients treated with radiation therapy alone.