It seems that in Japan, more public washrooms have been installing specific toilets catered for ostomates. Japan though has less percentage of bladder cancer patients (19,000 in 2013) but colon cancer is 3rd highest (75,000 in 2013). So I think there are many patients with ostomy.
Shizuoka-ken, a province of 3.5 million people, which is little more than greater Vancovuer of 2.5 million has about 80 public washrooms, in public facillities such as libraries, municipal halls, equipped with toilets designed for ostomates and in about 30 public washrooms in private facilities such as shopping malls with such toilet.
They use a specific sign so people can easily know if such toilet is equipped. See the attached picture for the sign.
I have also attached a few pictures of which different implementation of such toilets and also the one specifically designed for osmates.