[Smokin' Joe]

Or is it that young people with cancer and heart problems were more likely to watch more TV?

[KSCITYBOY]

Likely - association does not equal cause

[Harmless Teddy Bear]

Or is it that young people with cancer and heart problems were more likely to watch more TV?

There are not a lot of other things to do when you are laid up. You can read, do hand crafts, use the computer and watch tv.

If you really are not doing well, tv tends to win out, because it requires less effort.