Single metastatic lesion in isolated location (organ or site) was reported to associate with prolonged survival versus multiple metastatic lesions in isolated or multiple locations [ 14– 16].
The metastatic features assessed included the number of metastatic locations (isolated vs. multiple), the involvement of specific metastatic locations, and the number of metastases in each metastatic location (single vs. multiple).
Fig. 4 Multiple metastatic gastric polyps.
It is intriguing that in our study, both the number of metastatic lesions (single/multiple) and the number of metastatic locations (isolated/multiple) were significant associated with OS in univariate analysis.
CUP at many metastatic locations featured poorer prognosis than metastatic cancers with a known primary location and survival in CUP was comparable to that of metastatic lung cancer.
The metastatic locations, number of metastatic locations, and number of metastatic lesions were analyzed separately to identify the optimal grouping strategy (Table 3).
The association between the number of metastatic lesions (single/multiple) and OS has been extensively studied and demonstrated to be significant in NPC patients with synchronous and metachronous metastases by a series of studies [ 14, 15], whereas its prognostic value as compared with the number of metastatic locations remains unknown.
By contrast, few studies addressed the issue of the prognostic values of metastatic locations among patients with synchronous metastatic NPC.
The numbers of available samples of different metastatic locations were too small for statistical analysis.
The main metastatic locations are the bones and the central nervous system [ 1, 2].
