Population characteristics
There was no significant difference in terms of age (P=0.252) between the case and the control groups. Of them, 18, 27, 77, and 24 patients were classified as clinical stages I, II, III, and IV; 20, 32 and 92 patients were classified as pathological grades low, middle and high, respectively. Among these cases, 93 patients were postmenopausal, 76 patients had metastasis. According to IHC detection, the expression of ER in 4 patients was negative/mild positive, in 40 patients was strong positive; the expression of PR in 16 patients was negative/mild positive, in 32 patients was strong positive; the expression of wild type p53 in 37 patients was negative/mild positive, in 29 patients was strong positive; the expression of mutant p53 in 24 patients was negative/mild positive, in 36 patients was strong positive.
Correlation of FOXC2 gene polymorphisms with epithelial ovarian cancer susceptibility
The genotype frequencies of FOXC2 associated with epithelial ovarian cancer risk were shown in Table 1.Because rs1035550 G>A was not accordance with HWE (<0.05), we would not analyze the relationship between rs1035550 and epithelial ovarian cancer risk further. A positive association between rs3751749 C allele and epithelial ovarian cancer risk (TC vs. TT: adjusted OR=3.415, 95% CI=1.492-7.815, P=0.0036; recessive model: adjusted OR=3.707, 95% CI=1.645-8.353, P=0.0016). A positive association between rs4843163 C allele and epithelial ovarian cancer risk (GC vs. GG: adjusted OR=20.567, 95% CI=10.522-40.202, P<0.001; CC vs.GG: adjusted OR=1.691, 95% CI=1.034-2.765, P=0.0363; dominant model: adjusted OR=3.703, 95% CI=2.408-5.693, P<0.0001; recessive model: adjusted OR=15.831, 95% CI=8.449-29.664, P<0.0001). A positive association between rs4843396 C allele and epithelial ovarian cancer risk (TC vs. TT: adjusted OR=20.567, 95% CI=10.522-40.202, P<0.001; CC vs. TT: adjusted OR=1.691, 95% CI=1.034-2.765, P=0.0363; dominant model: adjusted OR=3.628, 95% CI=2.358-5.582, P<0.0001; recessive model: adjusted OR=23.546, 95% CI=14.555-44.837, P<0.0001).
Stratification analysis
The results were showed in Table 2 from stratification analyses of association between FOXC2 genotypes and epithelial ovarian cancer susceptibility, stratified by age, metastasis status, clinical stage, pathological grade, pregnant times, pausimenia, the expression of ER, PR, wild p53 and mutant p53. For age, FOXC2 rs3751794 CC genotype was significantly associated with increased epithelial ovarian cancer risk in both<53 years group (adjusted OR=5.289;95% CI=1.331-21.013, P=0.0180) and ≥53 years group (adjusted OR=3.010;95% CI=1.089-8.322, P=0.0337); rs4843163GC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in both<53 years group (adjusted OR=2.761;95% CI=1.600-4.764, P=0.0003) and ≥53 years group (adjusted OR=5.844;95% CI=2.585-12.115, P<0.0001); rs4843396TC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in both<53 years group (adjusted OR=3.239;95% CI=1.854-5.659, P<0.0001) and ≥53 years group (adjusted OR=4.272;95% CI=2.160-8.447, P<0.0001).
For metastasis status, FOXC2 rs3751794 CC genotype was significantly associated with increased epithelial ovarian cancer risk in no metastasis group (adjusted OR=5.018;95% CI=1.973-12.762, P=0.0007); rs4843163GC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in subgroups of metastasis (yes group: adjusted OR=2.913;95% CI=1.712-4.956 P<0.0001; no group: adjusted OR=4.839;95% CI=2.641-8.868, P<0.0001); rs4843396TC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in subgroups of metastasis (yes group: adjusted OR=3.199;95% CI=1.857-5.510 P<0.0001; no group: adjusted OR=4.082;95% CI=2.271-7.335, P<0.0001).
For clinical stage, FOXC2 rs3751794 CC genotype was significantly associated with increased epithelial ovarian cancer risk in stage 4 patients (adjusted OR=7.678;95% CI=2.730-24.878, P=0.0007);rs4843163GC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in three subgroups of clinical stage (stage 2: adjusted OR=3.312;95% CI=1.403-7.820, P=0.0063; stage 3: adjusted OR=4.087;95% CI=2.336-7.152, P<0.0001; stage 4: adjusted OR=6.973;95% CI=2.323-20.934, P=0.0005); rs4843396TC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in three subgroups of clinical stage (stage 2: adjusted OR=3.165;95% CI=1.332-7.523, P=0.0091; stage 3: adjusted OR=4.059;95% CI=2.317-7.109, P<0.0001; stage 4: adjusted OR=9.831;95% CI=2.866-33.714, P=0.0003).
For pathological grade, rs3751794 CC genotype was significantly associated with increased epithelial ovarian cancer risk in middle grade group (adjusted OR=11.327; 95% CI=4.166-30.792, P<0.0001); rs4843163GC/CC genotype (adjusted OR=11.608;95% CI=5.777-23.323, P<0.0001) and rs4843396TC/CC genotype (adjusted OR=8.452;95% CI=4.488-15.918, P<0.0001) was significantly associated with increased epithelial ovarian cancer risk in high grade group.
For pregnant times, rs3751794 CC genotype was significantly associated with increased epithelial ovarian cancer risk in >3 times group (adjusted OR=3.716;95% CI=1.093-12.627, P=0.0355); rs4843163GC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in subgroups of metastasis (≤3 times group: adjusted OR=5.652;95% CI=3.010-10.614 P<0.0001; >3 times group: adjusted OR=14.899;95% CI=4.457-49.802, P<0.0001); rs4843396TC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in subgroups of metastasis (≤3 times group: adjusted OR=5.710;95% CI=3.041-10.725 P<0.0001; >3 times group: adjusted OR=10.905;95% CI=3.749-31.719, P<0.0001).
For pausimenia, rs3751794 CC genotype was significantly associated with increased epithelial ovarian cancer risk in postmenopausal patients (adjusted OR=4.338;95% CI=1.805-10.412, P=0.0010); rs4843163GC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in subgroups of pausimenia(yes group: adjusted OR=4.998;95% CI=2.866-8.716 P<0.0001; no group: adjusted OR=2.303;95% CI=1.232-4.304, P=0.0089); rs4843396TC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in subgroups of metastasis ( yes group: adjusted OR=4.422;95% CI=2.569-7.612 P<0.0001; no group: adjusted OR=2.559;95% CI=1.404-5.035, P=0.0027).
Furthermore, we identified that rs4843163GC/CC genotype (adjusted OR=30.268; 95% CI=7.187-127.478, P<0.0001) and rs4843396TC/CC genotype (adjusted OR=14.474;95% CI=5.044-41.528, P<0.0001) was remarkably associated with strong positive ER expression. These two FOXC2 polymorphisms were significantly associated with subgroups of PR expression (rs4843163GC/CC vs. GG: negative/mild expression: adjusted OR=10.472;95% CI=2.350-46.667, P=0.0021; strong positive expression: adjusted OR=43.792;95% CI=5.890-325.594, P=0.0002; rs4843396TC/CC vs. TT: negative/mild expression: adjusted OR=6.567;95% CI=1.845-23.370, P=0.0037; strong positive expression: adjusted OR=21.295;95% CI=4.986-90.953, P<0.0001). For wild type p53 expression, rs3751794 CC genotype was significantly associated with increased epithelial ovarian cancer risk in strong positive group (adjusted OR=4.587;95% CI=1.324-15.869, P=0.0163); rs4843163GC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in subgroups of wild type p53expression (negative/mild expression: adjusted OR=24.209;95% CI=5.759-103.466, P<0.0001; strong positive expression: adjusted OR=9.412;95% CI=3.208-27.612, P<0.0001); rs4843396TC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in subgroups of wild type p53 expression (negative/mild expression: adjusted OR=15.909;95% CI=4.774-53.014, P<0.0001; strong positive expression: adjusted OR=9.412;95% CI=3.208-27.612, P=0.0001). For mutant p53 expression, rs3751794 CC genotype (adjusted OR=3.487;95% CI=1.024-11.876, P=0.0457 and rs4843163GC/CC genotype (adjusted OR=8.877;95% CI=3.360-23.451, P<0.0001) was significantly associated with increased epithelial ovarian cancer risk in strong positive group; rs4843396TC/CC genotype was significantly associated with increased epithelial ovarian cancer risk in subgroups of mutant p53 expression (negative/mild expression: adjusted OR=32.414;95% CI=4.318-243.321, P=0.0007; strong positive expression: adjusted OR=7.239;95% CI=2.927-17.901, P=0.0001).