Although the evidence for SCLC is not as strong for other solid tumors, it is believed that accel erated proliferation during TRT also exist in SCLC due to its characteristics of rapid doubling time and high growth fraction. Also, several studies explored the duration of radiotherapy together indirectly indicated that extended ORT had a potential negative effect in the treatment of LS SCLC. Therefore, we think that it is more appropriate to include ORT for the examina tion of the relationship between BED and treatment out comes in our analysis. Indeed the biological radiation dose in the high once daily or the concomitant boost TRT is higher compared to that used in the Intergroup Trial 0096, but at the expense of pro longed ORT which could potentially lead to repopula tion.

This should Inhibitors,Modulators,Libraries be considered as one of the reasons for the less satisfying results in the several phase II clinical trials exploring high radiation dose, and 45 Gy twice daily TRT should be considered as the stan dard treatment in LS SCLC at this time. Currently, two ongoing randomized Phase III trials are investigating the opti mal dose of radiation in LS SCLC. The former uses a conventional regimen of 66 Gy in 33 treatments given daily as the experiment arm, and the latter includes two experiment arms 70 Gy in 35 treatments given daily and 61. 2 Gy in 34 treatments given daily, 5 days week for 16 days, and then twice Inhibitors,Modulators,Libraries daily, 5 days a week for 9 days. Both trials are using the 45 Gy twice daily dose as the control arm, which will provide more data on the repopulation issue in LS SCLC.

The distributions of patient and treatment related characteristics were similar for low and high BED groups except for daily fraction scheme. Twice daily scheme was more frequent Inhibitors,Modulators,Libraries in high BED group than in low BED group. However, there was no significant difference in 5 years OS between the once daily and twice daily groups. This indicated that high BED administered in once daily scheme might lead to non inferior outcomes compared with twice daily scheme for LS SCLC. Therefore, we believed that the difference of daily fraction scheme between the two groups had no apparent impact on our conclusions. The differences between the physical constitution and patient compliance of the Inhibitors,Modulators,Libraries Asian and Western population may have resulted in different management of the LS SCLC patients here in China. The Turrisi et al.

schedule had been tried in our centre, but unsuccessful predo minantly because of severe esophagitis Inhibitors,Modulators,Libraries and bone mar row suppression occurred as a side effect in a large percentage of patients. In the past, there was no sufficient nutrition support and molecular weight calculator granulocyte colony sti mulating factor supply, and sequential treatment of LS SCLC was a more favourable treatment option in china, which was also common in other developing countries.