I really need to get better at prioritizing ideas I like that others have submitted. This one has been sitting on my to-strip-list for a year. A year! That's like ... one year! Disgraceful. I will make an effort to clear my list of approved submissions from now on, so if anyone feel that they have something worthy to be on this site, then shoot me a message and you can see it realised within a month.
Airspace suggested this strip based on the pokédex entries about Eevee which in the three early generations clearly states that the elementary stones emit radiation, which makes you wonder about the possible effects those items would have on humans given enough time. Particularly while carried around in a backpack.
You wouldn't need to know about those entries though, and I'm fairly certain the info box in the first panel should help anyone get all of the pieces in place. If not, speak up about it! I'm so used to comments made by well-informed pokémon fans that I sometimes forget how high I should raise the bar.
If anyone reading this strip is or knows someone suffering from cancer and feel that this joke is upsetting, I apologize in advance. The punchline is not that cancer is a funny thing. I have a coworker going through treatment right now and I truly wish she'll be alright. For those of you dealing with that disease directly or indirectly right now, you have my sympathies.
when I was younger and first played pokemon (Platnuim) I thought eevee could evolve into leafeon by using a leafstone but after a while I found out that it wasn't the case
the radiation of the Leaf Stones has caused his body to mutate and develop plant cells. Cancer is where your cells mutate into a different form that they aren't meant to. Thus, he's got a (most likely non-lethal) cancer.
Though he might be able to use grass attacks! Might be cool! (While he's alive still...
I understand the logic you're trying to make but personally I don't think Cancer has a place in any humour. Strip, Stand up, etc...