Objective: Using the volume calculating function of treatment planning system of 3DCRT to work out the value of GTV standard classifications and to provide the reference for clinical staging of esophageal carcinoma.
Methods: Six hundred and seven patients underwent radical resection of thoracic esophageal carcinoma in our hospital, and their pre-operative CT images were transmitted in digital format to the three-dimensional conformal radiotherapy planning system by the network. Esophageal lesion GTV targets were outlined, and their volumes were automatically computed by the planning system. Compared the differences of the GTV volumes in different pathological T stages, and analyzed the relationship between GTV volumes and pathological T stages. According to the median volume of GTV at different pathological T stages, divided the values of GTV volume corresponding to different T stages and selected the suitable classification standard of GTV volume.
Results: The esophageal carcinoma GTV length, maximum diameter and volume were related to pathological T staging and with a positive correlation (all P < 0.001). The Spearman correlation coefficient (r) was 0.376, 0.466 and 0.464, respectively, P < 0.001. Except that the length, maximum diameter and volume of GTV in pathological T3 and T4 had no significant difference, other indicators of the pathological T stages showed significant differences between the groups (P < 0.001). According to the median volume of GTV at different pathological T stages, the GTV volumes were divided into three grades: <or= 5.0 cm(3), 5.1 - 13.0 cm(3), and > 13.0 cm(3). When compared them with pathological T1, T2, and T3-T4 stages, the coincidence rate was 73.8%. The consistency was good between the GTV volume grades and pathological T stages (Kappa = 0.40, P < 0.001). The overall 5-year survival rates of GTV grades 1, 2, 3 were 78.1%, 31.5% and 33.5%, respectively (P < 0.0001). If the GTVs were divided into four grades: <or= 5.0 cm(3), 5.1 - 13.0 cm(3), 13.1 - 39.0 cm(3), and > 39.0 cm(3), the coincidence rate of GTV volume grades and pathology T staging was only 54.7%, and the consistency was poor, Kappa = 0.24, P < 0.001. The overall 5-year survival rate of GTV 1, 2, 3, 4 were 78.1%, 31.5%, 36.2% and 27.5%, respectively (P < 0.0001).
Conclusion: The length, maximum diameter and volume of esophageal carcinoma GTV are related to pathological T staging with a positive correlation. The classification that esophageal carcinoma GTVs divided into three grades has a good coincidence with the pathological T staging.