Comparing Gross Tumor Volume of Delineation between CT and MRI for Nasopharyngeal Carcinoma

Objective: To study the accuracy between CT and MRI in delineating gross tumor volume (GTV) of nasopharyngeal carcinoma (NPC) in making radiotherapy plan. Methods: The clinical data of 39 cases pathologically proven as nasopharyngeal carcinoma selected from April 2003 to September 2004 were retrospectively analyzed. All were subjected to CT and MR examination one week before treatment. CT scanning was performed with GE Light speed 16, and axial scan was parallel to the OM line routinely from soft palate to the suprasellar cistern. MR scanning was performed by GE Signa super-conducting magnetic resonance imaging system (1.5 Tesla). The standard quadrature head coil was used. Routine axial, sagittal and coronal image with SE sequence were obtained, and FLAIR was used in 10 of 21 cases. Scanned field ranged from the soft palate to the suprasellar cistern. Part of all cases underwent enhanced scanned with Ultravist in CT group or/and GD-DTPA in MR group. All data were analyzed by using the paired-samples t test. Results: The media primary tumor volume (cm3) in CT group and MR group was 32.49±19.91, 29.06±18.75, respectively, and the difference between the two groups were significant (t=5.268, P=0.000). There was significant difference between the two groups in early stage (T1+T2) and advanced stage (T3+T4) by Fuzhou Staging System (t=5.677, P=0.000; t=3.310, P=0.005, respectively). There was significant difference in stage T1, T2, T3 (P=0.005, P=0.001, P=0.004, respectively), and not in stage T4 (P=0.146) between the two groups. Conclusion: MR was more accurate than CT in delineating GTV of NPC, so, is more valuable in making radiotherapy plan.

Late course shrinking gross tumor volume (GTV) and boost radiotherapy for a special left lung cancer patient whose right lung was resected: a case report

We reported a special case of a locally advanced squamous cell carcinoma of the left lung. Due to pulmonary tuberculosis, the patient had underwent a complete right-side pulmonary lobectomy 20 years ago. Left lung supports his life, he is unable to carry on an operation treatment, so he accepted radiotherapy. Firstly, we defined gross tumor volume (GTV1) by CT simulation location, three-dimensional conformal radiotherapy (3D-CRT) was used until tumor dose reached 50 Gy/25 f. Secondly, by repeating the planning CT scan, defined GTV2, continued to radiotherapy by 2.5 Gy/f until the dose was 65 Gy/31 f. Using the same method for third CT scan, defined GTV3, continued to radiotherapy by 3 Gy/f until the total dose was 74 Gy/34 f. After radiotherapy, the patient acquired complete response and he had no obvious side-effect of radiotherapy. There has been no recurrence for 5 years now.

Prognostic value and predictive threshold of tumor volume for patients with locally advanced nasopharyngeal carcinoma receiving intensity-modulated radiotherapy

Background: Gross target volume of primary tumor(GTV?P) is very important for the prognosis prediction of patients with nasopharyngeal carcinoma(NPC), but it is unknown whether the same is true for locally advanced NPC patients treated with intensity?modulated radiotherapy(IMRT). This study aimed to clarify the prognostic value of tumor volume for patient with locally advanced NPC receiving IMRT and to ind a suitable cut?of value of GTV?P for prognosis prediction.Methods: Clinical data of 358 patients with locally advanced NPC who received IMRT were reviewed. Receiver oper?ating characteristic(ROC) curves were used to identify the cut?of values of GTV?P for the prediction of diferent end?points [overall survival(OS), local relapse?free survival(LRFS), distant metastasis?free survival(DMFS), and disease?free survival(DFS)] and to test the prognostic value of GTV?P when compared with that of the American Joint Committee on Cancer T staging system.Results: The 358 patients with locally advanced NPC were divided into two groups by the cut?of value of GTV?P as determined using ROC curves: 219(61.2%) patients with GTV?P ≤46.4 mL and 139(38.8%) with GTV?P >46.4 mL. The 3?year OS, LRFS, DMFS, and DFS rates were all higher in patients with GTV?P ≤46.4 mL than in those with GTV?P > 46.4 mL(all P < 0.05). Multivariate analysis indicated that GTV?P >46.4 mL was an independent unfavorable prognostic factor for patient survival. The ROC curve veriied that the predictive ability of GTV?P was superior to that of T category(P < 0.001). The cut?of values of GTV?P for the prediction of OS, LRFS, DMFS, and DFS were 46.4, 57.9, 75.4 and 46.4 mL, respectively.Conclusion: In patients with locally advanced NPC, GTV?P >46.4 mL is an independent unfavorable prognostic indi?cator for survival after IMRT, with a prognostic value superior to that of T category.