| BackgroundAt present,lung cancer ranks the first in the mortality rate of malignant tumors,among which the incidence of adenocarcinoma is increasing year by year.Most patients are in the middle and advanced stage when diagnosed,and have lost the opportunity of surgery.Radiotherapy is one of the main treatment methods for middle and advanced lung cancer.Due to the large tumor target volume of advanced lung cancer,it will lead to radiation damage to normal tissues,especially to the lung and esophagus,which will seriously affect the quality of life of patients.In clinical practice,respiratory gating,image guidance and dose adjustment are used to reduce the degree of radiation injury and its complications.In recent years,domestic and foreign scholars have also carried out research on the setting of target area,especially stereotactic radiotherapy,in which the setting of clinical target area is weakened and the exposure field is reduced.The purpose is to carry out reasonable target area delineation and reduce radiation damage and complications under the condition of ensuring the curative effect of radiotherapy.This study mainly focused on the setting of radiotherapy target area for locally advanced lung adenocarcinoma.ObjectiveBy setting intensity-modulated radiotherapy target area,the feasibility of omitting clinical target area for locally advanced lung adenocarcinoma was further explored.MethodsA total of 50 patients with locally advanced lung adenocarcinoma admitted to the Department of Radiotherapy of the Fifth Affiliated Hospital of Zhengzhou University from June 2017 to June 2018 were collected.According to random number table method,they were divided into study group and routine group,with 25 patients in each group.All patients completed two cycles of intensemodulated radiotherapy and pemetrexed combined with cisplatin.In the study group,gross tumor volume(GTV)was delineated,and then the planned target volume(PTV)was formed by direct outward expansion of 0.5～1.0cm.No clinical target area(CTV)was delineated for pulmonary tumors.In the conventional group,the gross tumor volume(GTV)was first delineated,then the clinical target volume(CTV)was formed by external radiotherapy of 0.8cm,and then the planned target volume(PTV)was formed by external radiotherapy of 0.5-1.0cm.The number of male and female cases in the study group was 14 and 11,respectively.The average age was(60.00±7.87)years in the range of 48-76 years.The average body weight was(61.88±9.60)kg in the range of44-75 kg.The clinical stages of stage IIIa,stage IIIb and stage IIIc were 9 cases,10 cases and 6 cases respectively.In the conventional group,there were 15 males and 10 females,ranging in age from 50 to 77 years old,with an average age of(58.96±10.43)years old.The body weight was in the range of 46-77 kg,and the average body weight was(61.96±8.94)kg.The clinical stages of stage IIIa,stage IIIb and stage IIIc were 9 cases,11 cases and 5 cases respectively.There was no statistically significant difference in age,gender,weight,stage and other clinical data between the two groups.All patients were positioned by enhanced CT scan after fixed body position.Then thin-layer lung image data were transferred into the TPS treatment planning system for image processing.Some patients with atelectasis and mediastinal lymph node metastasis underwent GTV contour according to PET-CT image data.The physical therapist prescribed the prescribed dose of PTV56～66Gy/28～ 33 F /5.6～ 7.0W,2Gy/ F,5 times/W,covering 95%PTV.Finally,a physician with associate senior professional title or above reviewed and optimized the treatment plan and carried out conformal intensemodulated radiotherapy.Concurrent chemotherapy was started from the first week of radiotherapy.Domestic pemetrexed500mg/m2 combined with cisplatin 75mg/m2 was used for 21 days,one cycle at least 2cycles.After follow-up of collecting data,apply SPSS19.0 statistical software for data analysis,comparative analysis in the near future curative effect(CR + PR),the long-term curative effect(local control and survival rate,no distant metastasis survival rate),and the adverse reaction(radioactive pneumonia,radioactive esophagitis,bone marrow suppression),the quality of life situation,and by using the COX model analysis of relevant factors affect curative effect.Results1.The effective rate(PR+CR)of the study group and the conventional group were 76%and 84%(P=0.480),and the disease control rate(CR+PR+SD)of the control group were96% and 100%(P=0.317),respectively,with no statistical significance(P>0.05).2.Kaplan-Meier analysis showed that the local control rate(P=0.713),overall survival rate(P=0.484)and distant metastasis-free survival rate(P=0.731)of the study group were close compared with the conventional group,and no statistical difference was found(P>0.05).Chi-square test was used to compare the local control rate,overall survival rate and distant metastasis-free survival rate between the study group and the conventional group at the first and second year,and there were no statistical differences(P>0.05).The results of Kaplan-Meier method were further verified.3.There were 10 cases of myelosuppression(40%)and 8 cases of myelosuppression(32%)in the study group and the conventional group(P=0.556),and 4 cases of radiation esophagitis(16%)and 5 cases of radiation esophagitis(20%)(P=0.713),respectively.There was no statistical difference between the two groups.Radiation pneumonia occurred in 2 cases(8%)and 9 cases(36%)(P=0.017),and there was a statistical difference between the two groups.4.In the study group and the conventional group,KPS>70 was scored in 15 cases(60%),8 cases(32%),11 cases(44%),2 cases(8%)and 6 cases(24%),respectively.There was statistically significant difference between KPS>70 and KPS<60(P=0.034).5.Multivariate analysis of Cox regression model showed that obstructive atelectasis,pulmonary infection and driver gene status were independent prognostic factors(P< 0.05),but had no significant correlation with gender,age,clinical stage,dose and target volume(P >0.05).Conclusion1.Intensity-modulated radiotherapy for locally advanced lung adenocarcinoma omitted the setting of clinical target area,the local control rate and survival rate did not decrease,and the incidence of radiation esophagitis and myelosuppression was similar;2.Omitting the setting of clinical target area can reduce the incidence of radiation pneumonia and help improve the quality of life of patients. |
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