Histology and differentiation grade
Ten studies (n = 352) reported an overall upstaging rate of 35.3% (95%CI: 21.8-48.7%) for patients with a serous EOC. Endometrioid EOC was evaluated in 11 studies (n = 270) and showed an upstaging rate of 19.7% (95%CI: 9.5-29.9%). A total of 7 studies (n = 167) reported the upstaging in clear cell EOC at 11.2% (95%CI: 3.1-19.4%). The lowest risk of upstaging was found in mucinous EOC (10 articles, n = 248) at 7.4% (95%CI: 3.6-11.2%) following comprehensive surgical staging (Figure 2). The differences between the subgroups are statistically significant (p<0.001).
Six studies evaluated the upstaging in low grade (n = 242) and high grade EOC (n = 326) with upstaging in 17.6% (95%CI: 12.8-22.3) and 40.9% (95%CI: 35.6-46.2%) of cases, respectively. The difference between the subgroups is statistically significant (p<0.001) (Figure 3). The included studies’ data did not permit analysis on the upstaging results of the various surgical components stratified for the histological types or differentiation grade.