He et al. BMC Cancer 2010, 10:681 http://www.biomedcentral.com/1471-2407/10/681 Page 7 of 11 Figure 4 Relationship between the changing ratio in size of target lesion and PSF among SD patients. Comparison of PFS of SD patients stratified by a reduction in target lesion size of (a) 25%, (b) 20%, (c) 15%, (d) 10%, (e) 5%. and (f) 0%. SD stable disease; PFS progression-free survival. prognosis of SD patients varies greatly due to the com- plexity of SD should be taken into careful consideration. Thus, a suggestion for further classification of SD is needed urgently for an alternative therapy at an early time. Certain further stratification of SD studies claim that an initial decrease in tumour size has little to do with overall survival, and no particular percentage of reduction in tumour size has been found to be