Risk stratification in GIST: shape quantification with CT is a predictive factor.

BACKGROUND: Tumor shape is strongly associated with some tumor's genomic subtypes and patient outcomes. Our purpose is to find the relationship between risk stratification and the shape of GISTs. METHODS: A total of 101 patients with primary GISTs were confirmed by pathology and immunohistochemistry and underwent enhanced CT examination. All lesions' pathologic sizes were 1 to 10 cm. Points A and B were the extremities of the longest diameter (LD) of the tumor and points C and D the extremities of the small axis, which was the longest diameter perpendicular to AB. The four angles of the quadrangle ABCD were measured and each angle named by its summit (A, B, C, D). For regular lesions, we took angles A and B as big angle (BiA) and small angle (SmA). For irregular lesions, we compared A/B ratio and D/C ratio and selected the larger ratio for analysis. The chi-square test, t test, ROC analysis, and hierarchical or binary logistic regression analysis were used to analyze the data. RESULTS: The BiA/SmA ratio was an independent predictor for risk level of GISTs (p = 0.019). With threshold of BiA at 90.5°, BiA/SmA ratio at 1.35 and LD at 6.15 cm, the sensitivities for high-risk GISTs were 82.4%, 85.3%, and 83.8%, respectively; the specificities were 87.1%, 71%, and 77.4%, respectively; and the AUCs were 0.852, 0.818, and 0.844, respectively. LD could not effectively distinguish between intermediate-risk and high-risk GISTs, but BiA could (p < 0.05). Shape and Ki-67 were independent predictors of the mitotic value (p = 0.036 and p < 0.001, respectively), and the accuracy was 87.8%. CONCLUSIONS: Quantifying tumor shape has better predictive efficacy than LD in predicting the risk level and mitotic value of GISTs, especially for high-risk grading and mitotic value > 5/50HPF. KEY POINTS: • The BiA/SmA ratio was an independent predictor affecting the risk level of GISTs. LD could not effectively distinguish between intermediate-risk and high-risk GISTs, but BiA could. • Shape and Ki-67 were independent predictors of the mitotic value. • The method for quantifying the tumor shape has better predictive efficacy than LD in predicting the risk level and mitotic value of GISTs.

[Application of standardized uptake value for FDG PET-CT in predicting radiation pneumonitis].

OBJECTIVE: To investigate the correlation of radiation pneumonitis (RP) with standardized uptake value (SUV) for fluorodeoxyglucose (FDG) positron emission tomography and computed tomography (PET-CT) in lung cancer patients treated with radiation therapy. METHODS: Fourty patients with unresectable non-small cell lung cancer (NSCLC) received FDG PET-CT before and after radiotherapy. The average SUV of the lung tissue irradiated with a dose of < or = 5 Gy, 5.1 approximately 15 Gy, 15.1 approximately 35 Gy, 35.1 approximately 60 Gy, >60 Gy were measured. The correlation between SUV and RP was analyzed by comparing the SUV in the patients with RP and without. The SUV ratio of the irradiated lung tissue to that of the non-irradiated lung tissue (L/B) was also calculated. RESULTS: Of the 40 patients, 8 developed RP, including 6 cases of grade 2 and 2 cases of grade 3. The SUV of irradiated lung tissues with a dose of 35.1 approximately 60 Gy was significantly correlated with RP. When SUV > or =1, the RP incidence rate was 41.7% versus 20.0% in the whole group, with a statistically significant difference. (chi2 = 3.96, P < 0.05). The sensitivity and specificity of SUV in predicting RP was 62.5% and 78.1%, respectively. When the value of L/B > or = 2.5, the RP incidence rate was 40.7% in this group versus 20.0% in the whole group, with a statistical significance (chi(2) = 4.92, P < 0.05). If taking L/B > or = 2.5 as a threshold value, the sensitivity and specificity in predicting RP was 72.7% and 90.9%, respectively. No statistically significant difference was found in predicting radiation pneumonitis between SUV > or =1 and L/B > or = 2.5 (chi2 = 0.002, P > 0.05). CONCLUSION: The standardized uptake value (SUV) and the SUV ratio of the irradiated lung tissue to that of the non-irradiated lung tissue (L/B) for FDG PET-CT are positively correlated with radiation pneumonitis, and clinicians may use it to predict the occurrence of radiation pneumonitis.

[Relationship of dose-volume histogram parameters and computed tomography grading of radiation-induced lung injury in patients with non-small cell lung cancer treated by three-dimensional conformal radiotherapy].

OBJECTIVE: To explore the relationship of dose-volume histogram (DVH) parameters and computed tomography grading of radiation-induced lung injury in patients with non-small cell lung cancer (NSCLC) treated by three-dimensional conformal radiotherapy (3D-CRT). METHODS: One hundred sixty-nine patients with stage I approximately III NSCLC, treated by 3D-CRT and followed by CT scan for more than six months after 3D-CRT, were divided into grade 0 to grade 4 based on the appearance of radiation-induced lung injury on CT image defined jointly by radiotherapist and radiologist. The patients were divided into CT positive group (grade 2 to grade 4) and CT negative group (grade 0 to grade 1), then the treatment planning shown to the patients were reviewed to compare and analyze the relationship of CT grading of radiation-induced lung injury and the DVH parameter selected. RESULTS: Regardless of whole lung or tumor-bearing lung, there was a statistically significant difference in normal tissue complication probability (NTCP) between the patients grouped with different CT grading of radiation-induced lung injury, and the mean of NTCP increased along with upgrade of CT grading. There was a statistically significant difference of mean lung dose (MLD) regardless of whole lung or tumor-bearing lung between the patients grouped with different CT grading of radiation-induced lung injury, and MLD increased along with upgrade of CT grading. There was a statistically significant difference of the volume received equal or more than 20 Gy (V(20)), 30 Gy (V(30)), 40 Gy (V(40)) of whole lung and tumor-bearing lung between the patients grouped with different CT grading of radiation-induced lung injury, and V(20), V(30), V(40) increased along with upgrade of CT grading. There were not statistically significant differences of the DVH parameters of the contralateral lung in the patients of different groups based on the CT grading. On statistical analysis, the DVH parameters of whole lung and tumor-bearing lung closely correlated with CT grading of radiation-induced injury of the tumor-bearing lung, and there was a relatively strongest relationship between NTCP and CT grading of the tumor-bearing lung (eta = 0.522). CONCLUSION: DVH parameters such NTCP, MLD, V(20), V(30), and V(40) are statistically correlated closely with CT grading of radiation-induced lung injury after radiotherapy for the patients with NSCLC treated by 3D-CRT. Therefore the parameters can be selected as the reference for evaluation after 3D-CRT for patients with NSCLC.