There was a cancel button on pretty much every form until about 2 days ago when I removed it. The back button used to be a non-starter in the early days of the web and that made cancel buttons a common pattern, but users have warmed up to the back button today (and swiping right to go back is pretty much second nature on touch devices).

Plus, if you use the back button, you go back exactly where you were in the previous page, even if you’d scrolled down a bit. When you hit a cancel button, you’re not going back. You’re actually going forward because you’re reloading the previous page, which causes you to lose your place. I could map the cancel button to the back button using JavaScript, but that would be redundant.

Eventually, these edit forms will be inline anyway.