[Show abstract][Hide abstract] ABSTRACT: High-precision radiation therapy techniques such as IMRT or sterotactic radiosurgery, delivers more complex treatment fields than conventional techniques. The increased complexity causes longer dose delivery times for each fraction. The purpose of this work is to explore the radiobiologic effect of prolonged fraction delivery time on tumor response and survival in vivo.
1-cm-diameter Lewis lung cancer tumors growing in the legs of C57BL mice were used. To evaluate effect of dose delivery prolongation, 18 Gy was divided into different subfractions. 48 mice were randomized into 6 groups: the normal control group, the single fraction with 18 Gy group, the two subfractions with 30 min interval group, the seven subfractions with 5 min interval group, the two subfractions with 60 min interval group and the seven subfractions with 10 min interval group. The tumor growth tendency, the tumor growth delay and the mice survival time were analyzed.
The tumor growth delay of groups with prolonged delivery time was shorter than the group with single fraction of 18 Gy (P < 0.05). The tumor grow delay of groups with prolonged delivery time 30 min was longer than that of groups with prolonged delivery time 60 min P < 0.05). There was no significant difference between groups with same delivery time (P > 0.05). Compared to the group with single fraction of 18 Gy, the groups with prolonged delivery time shorten the mice survival time while there was no significant difference between the groups with prolonged delivery time 30 min and the groups with prolonged delivery time 60 min.
The prolonged delivery time with same radiation dose shorten the tumor growth delay and survival time in the mice implanted with Lewis lung cancer. The anti-tumor effect decreased with elongation of the total interfractional time.
[Show abstract][Hide abstract] ABSTRACT: To summarize our experience and treatment results in lymph node-negative nasopharyngeal carcinoma treated in a single institution.
From January 2000 to December 2003, 410 patients with lymph node-negative nasopharyngeal carcinoma were retrospectively analyzed. The T-stage distribution was 18.8% in T1, 54.6% in T2 (T2a, 41 patients; T2b, 183 patients), 13.2% in T3, and 13.4% in T4. All patients received radiotherapy to the nasopharynx, skull base, and upper neck drainage areas, including levels II, III, and VA. The dose was 64-74 Gy, 1. 8-2.0 Gy per fraction over 6.5-7.5 weeks to the primary tumor with (60)Co or 6-MV X-rays, and 50-56 Gy to levels II, III, and VA. Residual disease was boosted with either (192)Ir afterloading brachytherapy or small external beam fields.
The median follow-up time was 54 months (range, 3-90 months). Four patients developed neck recurrence, and only 1 patient (0.2%) experienced relapse outside the irradiation fields. The 5-year overall survival rate was 84.2%. The 5-year relapse-free survival rate, distant metastasis-free survival rate, and disease-free survival rate were 88.6%, 90.6% and 80.1%, respectively. Both univariate and multivariate analyses demonstrated that T classification was the only significant prognostic factor for predicting overall survival. The observed serious late toxicities were radiation-induced brain damage (7 cases), cranial nerve palsy (16 cases), and severe trismus (13 cases; the distance between the incisors was < or = 1 cm).
Elective levels II, III, and VA irradiation is suitable for nasopharyngeal carcinoma without neck lymph node metastasis.
International journal of radiation oncology, biology, physics 08/2010; 77(5):1397-402. · 4.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Anastomotic leakage is a serious complication in rectal cancer surgery. More than one third of rectal cancer patients with low anterior resection (LAR) will receive defunctional stomas during primary operation.
Six hundred thirty-nine consecutive rectal cancer patients, whose tumors were located 5 to 12 cm from the anal verge, were treated with LAR. A standardized pelvic drainage for all these patients and selective irrigation for patients with leakage were conducted, and defunctional stoma was used as a salvage modality. All the anastomoses were all extraperitonealized during primary operations.
The anastomotic leakage rate was 7.04%. Male gender and location of tumor were found to be risk factors for leakage in patients with LAR. The overall stoma rate was 1.88%. Nearly 75% of leakage could be cured by irrigation-suction without surgical intervention. Severe complications, such as peritonitis, fistula, and obstruction, were strong predictors of irrigation failure.
Extraperitonealized anastomosis and pelvic drainage obtained a very low rate of defunctional stoma for LAR. Pelvic irrigation-suction was an effective modality to resolve anastomotic leakage.
American journal of surgery 10/2009; 199(6):753-8. · 2.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Many patients with nasopharyngeal carcinoma (NPC) have marked anatomic change during intensity-modulated radiation therapy (IMRT). In this study, the magnitude of anatomic changes and its dosimetric effects were quantified. Fifteen patients with locally advanced NPC treated with IMRT had repeated computed tomography (CT) after 18 fractions. A hybrid plan was made to the anatomy of the second computed tomography scan. The dose of the original plan, hybrid plan, and new plan were compared. The mean volume of left and right parotid decreased 6.19 mL and 6.44 mL, respectively. The transverse diameters of the upper bound of odontoid process, the center of odontoid process, and the center of C2 vertebral body slices contracted with the mean contraction of 8.2 mm, 9.4 mm, and 7.6 mm. Comparing the hybrid plan with the treatment plan, the coverage of target was maintained while the maximum dose to the brain stem and spinal cord increased by 0.08 to 6.51 Gy and 0.05 to 7.8 Gy. The mean dose to left and right parotid increased by 2.97 Gy and 2.57 Gy, respectively. A new plan reduced the dose of spinal cord, brain stem, and parotids. Measurable anatomic changes occurring during the IMRT for locally advanced NPC maintained the coverage of targets but increased the dose to critical organs. Those patients might benefit from replanning.
Medical dosimetry: official journal of the American Association of Medical Dosimetrists 07/2009; 35(2):151-7. · 1.26 Impact Factor