He et al. BMC Cancer 2010, 10:681 http://www.biomedcentral.com/1471-2407/10/681 Table 2 Patient Characteristics Age, year, median Sex, % Female Male Stage, % IIIB IV ECOG performance status, % 0 1 Weight loss ≥5%, % 56 15(41%) 22(59%) 13(35%) 24(65%) 25(68%) 12(32%) 14(38%) Response after 2 courses of platinum-based chemotherapy PR (n = 37) (%) SD (n = 117) (%) 57 47(40%) 70(60%) 44(38%) 73(62%) 59(50%) 58(50%) 50(43%) P 0.286 0.968 0.786 0.068 0.598 Page 5 of 11 PR Partial Response; SD Stable Disease; ECOG Eastern Cooperative Oncology Group. confidence interval, 187-310 days) for the 37 patients with PR and 220 days (95% confidence interval, 191-248 days) for the 117 patients with SD. The log-rank test found no significant difference of PFS (P = 0.991) between the PR and SD subgroups (Figure 3a). The total follow-up time ranges from 2 months to 40 months, and by the end of the last follow-up time (Sept, 2010), 22 is still alive (5 PR, 17 SD). The median OS was 364 days (95% confidence interval, 275-452 days) for the PR patients and 350 days (95% confidence interval, 293-406 days) for the SD patients respectively. The log-rank test found no significant difference of OS (P = 0.861) between the PR and SD subgroups (Figure 3b). Relationship between Change in Target Lesion Size and PFS and OS among Initial SD Patients The response rate varied significantly according to the definition of “response rate” (Table 3). The median PFS of patients with ≥25%, ≥20%, ≥15%, ≥10%, ≥5% or ≥0% decrease in tumour size was 289 days, 270 days, 242 days, 225 days, 221 days or 221 days, respectively; the median OS was 377 days, 412 days, 385 days, 387 days, 385 days and 350 days, respectively. The P value asso- ciated with the log-rank test comparing the PFS and OS of responding patients with that of non-responding patients using different definitions of response are shown in Table 3 and Figure 4 and Figure 5. As indi- cated, no significantly better cut-off point, i.e. optimal percentage of decrease in tumour size, was found in pre- dicting the PFS and OS of the patients with SD. In addi- tion, among SD patients, those with an initial decrease of 30-20% in tumour size were not significantly distin- guishable (P > 0.05) from those with an initial increase. Multivariate analysis included factors such as sex, age, weight loss, ECOG performance status, and stage of dis- ease, which might have a potential effect on prognosis Figure 3 Comparison of PFS (a) and OS (b) between PR and SD. PR partial response; SD stable disease; PFS progression-free survival; OS overall survival.