He et al. BMC Cancer 2010, 10:681 http://www.biomedcentral.com/1471-2407/10/681 Table 3 Variable Response Criteria Definition of responder ≥25% Reduction in tumour ≥20% Reduction in tumour ≥15% Reduction in tumour ≥10% Reduction in tumour ≥5% Reduction in tumour ≥0% Reduction in tumour Group Nonresponder Responder Nonresponder Responder Nonresponder Responder Nonresponder Responder Nonresponder Responder Nonresponder Responder No 100 17 82 35 66 51 54 63 46 71 17 100 218(176-259) 289(225-352) 218(171-264) 270(181-358) 200(149-250) 242(190-294) 198(127-268) 225(176-273) 218(147-289) 221(177-265) 198(105-291) 221(193-249) Page 6 of 11 P 0.240 0.168 0.323 0.334 0.362 0.448 P 0.319 0.874 0.937 0.948 0.789 0.913 86 14 71 29 57 43 47 53 40 60 15 85 335(261-408) 377(338-415) 323(276-369) 412(328-495) 323(279-366) 385(309-460) 320(268-371) 387(320-453) 320(272-367) 385(317-452) 323(195-450) 350(286-413) Median PFS(95%CI) Dead No. Median OS(95%CI) 95% CI indicates 95% Confidence Interval; PFS Progression-free Survival; OS Overall survival. of NSCLC patients. Table 4 indicates that ECOG 1 and weight loss of ≥5% was relatively worse for predicting PFS (P < 0.05). Cox regression analysis showed that other prognostic factors like age, sex, stage of disease, the percentage of change in target lesion size of patients with SD derived from the initial assessment after the first two courses of chemotherapy are not associated with PFS (P > 0.05) Discussion OS has long been considered to be the most important indicator of clinical efficacy endpoints for any treatment regimen. However, OS requires prolonged follow-up, and is often affected significantly by other factors, such as the effects of second-line and subsequent therapies and so it cannot be used as a scale for adjusting first- line treatments. PFS, a biological indicator, can be applied to measure tumour burden directly. Especially, PFS can swiftly and accurately indicate the survival ben- efit of the first-line therapy, which enables clinicians to modify their treatment projects as soon as possible. Recent research has found that PFS is correlated posi- tively with OS and it has been accepted as a surrogate for OS in advanced cancer [17-22]. RECIST, which is based on morphological features of the tumour, has been adopted as a norm for clinical trials. According to RECIST, patients who demonstrate a response often continue with their treatment proto- cols, and termination of the original therapeutic regimen and replacement with another has been considered for those who do not respond. In clinical practice, however, it is common to find that some patients demonstrate a dramatic response to chemotherapy, but they might not have any survival advantage when compared with the patients who do not respond [23,24]. Other patients who demonstrate SD or a minimal disease progression might end up with extended long-term survival. Focusing on this phenomenon, Katherine R et al. reached the conclusion that in their study of patients with advanced NSCLC there was no significant differ- ence between the initial response categories of PR and SD with respect to overall survival [25]. In addition, Lara et al. suggested that SD enjoys equal survival signif- icance with CR and PR. They claim that DCR, com- posed of CR, PR and SD, is more powerful than response i.e. CR and PR alone in predicting the overall survival of patients with advanced NSCLC [2]. Some experts suggest that SD might represent a potential sur- vival benefit of chemotherapy. Therefore, the distinction between SD and PR might be of no practical importance [26,27]. Similar to the studies mentioned above, the results of the current study suggest that tumour shrinkage in the CT image derived from the initial treatment-assessment after the first 2 courses of first-line chemotherapy, i.e. early radiographic response in patients with advanced NSCLC is not positively related with their PFS and OS, thus, it cannot predict the outcome of chemotherapy. That is to say, patients with PR and SD derived from their initial assessment have similar PFS and OS. So, PR and SD enjoy the same clinical significance in predicting PFS or even OS according to RECIST. It is clear that patients with SD have also benefited from the continua- tion of the original treatment. The creative point is that this prospective study adopts treatment schemes with similar effectiveness to reduce any possible bias, and PFS as the end point, which can reflect effectiveness of their first-line treatment at a relatively early time, thus early adjustment of treatment is likely to be adopted. SD is often used as a decisive point in treatment man- agement in clinical research, but it is regarded as a cate- gory with much controversy. Continuation of the original treatment for the NSCLC patients with initial SD has been generally adopted. But the notion that