rmtree doesn't handle such exclusions, however this task can also be achieved using some standard command line tools e.g.

+4:35% find . -wholename '*/cache/*'
./cache/01
./cache/01/aa
./cache/02
./cache/02/aa
./cache/_01
./cache/_01/aa
+4:35% find . -wholename '*/cache/*' ! -wholename '*_*'
./cache/01
./cache/01/aa
./cache/02
./cache/02/aa
+4:35% find . -wholename '*/cache/*' ! -wholename '*_*' | xargs rm -rf
+4:36% find . -wholename '*/cache/*'
./cache/_01
./cache/_01/aa
[download]

See find, xargs