Literature and study characteristics
All published cases of Xp11.2 tRCC were enrolled except a few of cases could not meet the inclusion criteria. 9 studies with 209 cases were collected. It was also checked that all cases were unique, no repeated cases were included. For common types of kidney cancer, 7 studies were included in quantitative synthesis for meta-analysis, as shown in Table 1 and Table 2. Publication bias is described as visual assessment of a funnel plot in Figure 2 and there was no evidence for significant publication bias.
Results of the search
All collected studies
Totally, there were 131 females and 78 males while all the cases according our inclusion criteria were enrolled in. Previous literature has reported significant gender differences in Xp11.2 tRCC between adults and children, so patients of Xp11.2 tRCC was divided into children (≤ 14 years) and adults (> 14 years) for further analysis. The three most common types of renal cell carcinoma, clear cell carcinoma, papillary cell carcinoma, and chromophobe cell carcinoma, were used for comparative analysis.
Gender-related incidence of all included studies of Xp11.2 tRCC
A total of 209 cases with 131 women and 78 men were included. Tests for heterogeneity showed that P=0.002 and I²=60%. We applied random- effect model while I² value>50%. Pooled OR was 2.84 (95 % CI = 1.48–5.45) (Fig. 3A).
Gender-related incidence of included adult studies of Xp11.2 tRCC
A total of 178 cases of Xp11.2 with 116 women and 62 men were included. (I2 statistic = 31 %, P < 0.00001)，so that Mantel-Haenszel fixed-effect model was still applied. Pooled OR was 3.37 (95 % CI =2.19–45.18) (Fig. 3B).
Gender-related incidence of included children studies of Xp11.2 tRCC
For this group, there was no evidence for heterogeneity about incidence of different gender (I2 statistic = 0 %, P = 0.52). Results of meta-analysis demonstrated that The incidence is similar between male and female with pooled OR of 0.76(95 % CI = 0.32–1.77) (Fig. 3C).
Gender-related incidence of PRCC, CCRCC and ChRCC
7 studies were included in quantitative synthesis for meta-analysis. For pRCC, a total of 5500 cases with 1320 women and 4180 men were included. The pooled OR was 0.10(95 % CI = 0.09–0.11) (Fig. 4B). For ccRCC, we got similar results. The pooled OR was 0.32 (95 % CI = 0.26–0.41) (Fig. 4A). Results of ChRCC showed that the OR of ChRCC was 0.47(95 % CI = 0.39–0.56) (Fig. 4C).
Gender-related distant and lymphatic metastases of Xp11.2 tRCC
A total of 209 cases with 131 women and 78 men were included. Tests for heterogeneity showed that no evidence of heterogeneity in the incidence of distant metastasis (I2 statistic = 32 %, P = 0.86) and lymphatic metastasis (I2 statistic = 0 %, P = 0.35) was observed in two pool. The results showed that the rates of lymphatic metastasis (OR = 1.47, 95 % CI = 0.66–3.24) (Fig. 5A) and distant metastasis (OR = 1.09, 95 % CI = 0.44–1.72) (Fig. 5B)were comparable between male and female patients.