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Objective To investigate the optimization of therapeutic regimen through the adjustment of the minimum sub-field area in intensity-modulated radiotherapy (IMRT) for cervical cancer,under the premise of no influence on the dose to target volume or organs at risk.Methods A total of 12 patients with pathologically confirmed cervical cancer were enrolled,and the prescribed dose to the planning target volume (PTV) was 50 Gy in 25 fractions.The Pinnacle 8.0m treatment planning system was used for all patients,and 16 IMRT plans were developed for each patient,with the application of 9 evenly distributed fixed incidence directions (0°,40°,80°,120°,160°,200°,240°,280°,and 320°),a minimum sub-field number of 80,and a minimum sub-field hop count (MU) of 5 MU.The range of sub-field area was 2-81 cm2.Direct machine parameter optimization was used for inverse-planned optimization calculation,and all the plans met the requirements of the clinical prescribed dose.The dose-volume histogram was used to evaluate the dose distribution in target volume and organs at risk.Results With the sub-field area increasing from 2 cm2 to 81cm2,the total hop count of IMRT plan was reduced from (1405±170) MU to (490±47) MU (P=0.000),and when the sub-field area increased above 6 cm×6 cm,the total hop count was reduced significantly (P=0.000).In the IMRT plan with a minimum sub-field area of 2-49 cm2,there was no significant difference in dose between the target volume and the organs at risk (P＞0.05).The dose to the rectum,the bladder,and both femoral heads showed no significant differences across the IMRT plans with different minimum sub-field areas (P＞0.05).Conclusions When the Pinnacle 8.0m treatment planning system is used to develop IMRT plans for cervical cancer,the requirements for clinical dose can still be met with a minimum sub-field area reaching 7 cm×7 cm,and there are significant reductions in sub-field hop count and total hop count.
ABSTRACT
<p><b>OBJECTIVE</b>To analyze the prognostic factors for esophageal carcinoma patients with stump carcinoma and atypical hyperplasia after esophagectomy.</p><p><b>METHODS</b>From August 2006 to December 2010, 182 esophageal carcinoma patients with stump carcinoma and atypical hyperplasia after esophagectomy treated in our hospital were involved in this study, including 60 cases with grade I-II atypical hyperplasia, 23 cases with grade III atypical hyperplasia, 37 cases with carcinoma in situ, and 62 cases with invasive carcinoma. Prognostic factors for these patients were analyzed.</p><p><b>RESULTS</b>The 1-, 2-, 3- and 4-year locoregional control rates of these 182 patients were 77.1%, 63.3%, 60.3% and 60.3%, respectively, and the over-all cumulative survival rates were 78.6%, 63.9%, 46.3% and 41.0%, respectively. A total of 56 cases suffered from locoregional recurrence (56/182, 30.8%), including anastomotic recurrence and lymph node metastasis. The number of locoregional recurrence patients of grade I-II of atypical hyperplasia was 13(13/60, 21.7%), grade III atypical hyperplasia and carcinoma in situ 21 (21/60, 35.0%), and invasive carcinoma 22 (22/62, 35.5%). There were no significant differences among the three groups(χ(2) = 3.485, P = 0.175). There were significant differences in locoregional control rate and survival rate among the four treatment groups (P < 0.05). For patients with stump grade I∼II atypical hyperplasia and different stage positive stump margin, the 1-, 2-, 3- and 4-year survival rates of the four treatment groups had significant differences (P < 0.05). As for locoregional control rates, there were no significant differences in the four groups (P > 0.05). Univariate analysis showed that tumor length, depth of invasion, number of metastatic lymph nodes, number of lymph node metastatic fields, pTNM stage, stump pathological grade and treatment modality were main influencing factors for survival rate (P < 0.05);invasion depth, stump pathological grade and treatment modality were important factors for locoregional control. Multivariate Cox regression analysis showed that tumor length, number of metastatic lymph nodes, stump pathological grade and treatment modality were independent influencing factors for survival (all P < 0.05);invasion depth, stump pathological grade and treatment modality were independent influencing factors for locoregional control (all P < 0.05).</p><p><b>CONCLUSIONS</b>For the patients with stump carcinoma and atypical hyperplasia after esophagectomy, tumor length, number of metastatic lymph nodes, stump pathological grade and treatment modality are independent influencing factors for long-term survival, and invasion depth, stump pathological grade and treatment modality are independent influencing factors for locoregional control.</p>