He et al. BMC Cancer 2010, 10:681 http://www.biomedcentral.com/1471-2407/10/681 treatment to death resulting from any cause. The Kaplan-Meier curve was used to describe PFS and OS, and a log-rank test was used to compare the PFS and OS of each category defined according to the percentage reduction in tumour size i.e. ≥30% [PR], ≥25%, ≥20%, ≥15%, ≥10%, ≥5%, and ≥0%.The c2 test was used for qualitative data analysis, and the Kruskal-Wallis test or variance analysis was used to analyse the quantitative data. Variables included in the multivariate analysis were age, sex, grade of the disease, ECOG performance status, and weight loss. P < 0.05 was set as the level of statistical significance. Results Distribution of Response Categories and Patient Characteristics Altogether, 188 patients were enrolled in the trial but 9 withdrew after completing their first cycle of che- motherapy. (Four refused to accept the treatment, one died from myocardial infarction, three received radio- therapy for the their target lesions, and one experienced PD with osseous metastasis.) The remaining 179 patients with inoperative NSCLC had the initial assess- ment after the first two courses of first-line platinum- based chemotherapy: 37 achieved PR and 117 were regarded as SD and these 154 patients (PR + SD) were eligible for the final analysis (Figure 1). The remaining 25 had PD and no CR according to RECIST. Table 1 summarizes the characteristics of the patients included in this analysis. The median age of the patients when enrolled into the study was 57 years (range 26 - 77 years), with 38% > 60 years. A total of 92 males (60%) were eligible for the analysis. The vast majority of patients (63%) had stage IV disease, 64 patients (42%) reported a weight loss of ≥5%, and the majority of patients had an ECOG performance status of 0 or 1. Table 1 Patient Characteristics Characteristics Age, years Median Range Sex Female Male Stage IIIB IV ECOG performance status 0 1 Weight loss ≥5% Yes No Page 4 of 11 Patients(PR + SD) (n = 154) 57 26-77 62 92 57 97 84 70 64 90 PR Partial Response; SD Stable Disease; ECOG Eastern Cooperative Oncology Group. Distribution of Change in Tumour Size of Initial SD Patients Among the patients with SD derived from the assess- ment after the first two courses of first-line platinum- based chemotherapy there was a decrease of tumour size of 25-30% for 17, 20-25% for 18, 15-20% for 16, 10- 15% for 12 and 5-10% for 8 and 0-5% for 29. The increase of tumour size in the other patients was <20%. The result is depicted in waterfall plots (Figure 2). Comparison of PFS and OS of Patients with Initial PR and SD The patients were divided into two subgroups (PR and SD) after two courses of treatment. Careful examination found no statistically significant difference of patient characteristics between the two groups, i.e. baseline characteristics were well balanced between PR and SD (Table 2). The median PFS was 249 days (95% Figure 1 Consort diagram of patient denominator. PR partial response; SD stable disease; PD progressive disease. Figure 2 Initial evaluation among SD patients in waterfall plot distribution (range -29% to +19.9%). SD stable disease.