Abstract:

ObjectiveTo compare sideeffect of highdose conventional fractionation (HF) and conventional fractionation (CF) in threedimensional conformal radiotherapy (3DCRT) on the heart for nonsmallcell lung cancer (NSCLC), and to explore an effective prediction on radiationinduced myocardial hearts. MethodsFrom April 2004 to January 2007, a total of 60 patients with stage ⅠⅢ NSCLC were randomized into the HF group and the CF group, with 30 patients in HF group treated by 4?Gy/f, 72?Gy/18?f/24?d and 30 patients in the CF group by 2?Gy/f, 72?Gy/36?f/50?d. Troponin I (cTnI) in blood was determined before radiotherapy, at a dose of 40?Gy, at the end of radiotherapy and one month after radiotherapy. A 24hour ambulatory electrocardiography (24?hAECG) was performed at the end of radiotherapy. The radiationinduced pericardium injury was evaluated by CT. One year later, patients were subjected to myocardial single photon emission computerized tomography (SPECT) and the color Doppler echocardiography(CDE) test. ResultsAll 60 patients completed radiation treatments. During a follow up of 12 months, the serum cTnI level in the HF group was significantly higher than in the CF group at a dosage of 40Gy and at the end of radiotherapy. Differences in results of 24?hAECG, SPECT and CDE and incidence of radiation pericardium injury between the two groups were not statistically significant. The serum cTnI level at a dosage of 40?Gy, V30, and isoeffective dose for 1/3 isoeffective volume(D1/3) were independent risk factors for radiationinduced myocardial fibrosis. ConclusionDuring the oneyear observation, HF had no increased incidence of radiationinduced heart complications, but its longterm effect is unknown. DVH combined with cTnI serum concentration could improve the sensitivity and specificity for identification of radiationinduced myocardial fibrosis.

Key words: Carcinoma, nonsmallcell lung; Dose fractionation;Radiotherapy, conformal; Heart injuries