不太能理解这段，望各位战友指点一下

Within the total cohort of pediatric AML, follow-up data were available for 205 patients, including 17 cases with high BRE expression. No differences were found for 3-year pEFS between cases with high and low BRE expression (53 ± 12 vs 43 ± 4%, P¼0.61) and for 3-year pOS (64 ± 12 vs 62 ± 4%, P¼0.77). However, the cases with a high BRE expression had a higher 3-year pRFS as compared with cases with a low expression (82 ± 12 vs 52 ± 4%, P¼0.01) (Figure 3a). Within the MLL-rearranged cases, high BRE expression suggested a better 3-year pEFS compared with those with a low BRE expression (50 ± 13 vs 21 ± 8%, P¼0.12) and a better 3-year pOS (62 ± 13 vs 32 ± 9%, P¼0.19), but the results were  not statistically significant. However, again, cases with high BRE expression had a significantly better 3-year pDFS compared with cases with a low expression (80 ± 13 vs 32 ± 11%, P¼0.03) (Figure 3b).

不太能理解，这两个however后面的部分和前面有什么区别？however前面：BRE高表达和低表达组的pEFS没有差异；however后面：BRE高标大组较低表达组，pEFS更高。个人不太能够理清楚二者的区别，望各位战友指点一下。谢谢