Nope. Can lights are generally mounted using their own "straps", and
often times are held in place with little more than a cable staple or
2. Don't attempt to hang anything from it.
But, the good news is that can lights are mounted between joists, and
are also easily disassmbled from the outside in.
The other good news is that they make ceiling boxes for ceiling fans
that are ideal for your situation - there is a bolt in the middle of
the box that you turn, which causes it's arms to extend out and wedge
into the joists. Google around for ceiling fan box, or something
Take your time.... remove the old fixture, install the new ceiling box,
and the most difficult part will probably be patching the sheet rock
around the box.