Cryopreservation for delayed circulating tumor cell isolation is a valid strategy for prognostic association of circulating tumor cells in gastroesophageal cancer

Figure 2 Circulating tumor cell enumeration by processing method. Mean number of CTCs isolated in the fresh specimens were higher than in the matched cryopreserved sample (mean difference in CTCs 17.1 95%CI: 0.7-33.6, P = 0.043). This difference was mostly driven by larger falls in CTC counts in samples with high numbers of CTCs (> 50 CTCs in fresh samples), with no significant difference in CTC counts for samples with less than 50 CTC in the fresh specimen (P = 0.06).