There is an unmeasurably large amount of suffering due to cancer. Not just from the people that have directly experienced it. Watching helplessly as it consumes the bodies and minds of your loved ones is devastating. Its likely that someone expressing that sentiment has dealt with that fallout. My heart goes out to them.

I remember an xkcd strip ending with that phrase: https://xkcd.com/931/

I think until you have someone close experience it you can't truly appreciate the sentiment. From my experience, having someone go through it is an awful, helpless time. I've heard having parents go through alzheimers is similar.

I don't know if it's thought of in popular culture as "coming from" a specific source, but I know people have been saying it for a lot longer than the internet. It's been independently coined a million times at least. It's really the only thing you can think to say sometimes to sum up the experience for everybody involved.

It's the cancer version of the Old Man Yells at Cloud meme.

Surely you mean cancer is not only to blame?! Even then, that only applies to cancer than doesn’t manage to destroy or end your life… it’s still a horrible scourge that causes great anguish in any health care system conceivable.

*In America

"Positive sentiments? Psh, sarcasm is way more fun"