Explain xkcd: It's 'cause you're dumb.
Title text: Now, if it selectively kills cancer cells in a petri dish, you can be sure it's at least a great breakthrough for everyone suffering from petri dish cancer.
Cancer is one of the most feared illnesses due to high mortality and a topic visited by Randall in past comics.
Whenever a study finds a hint of a cure, it is hyped up in media as major breakthrough. However, because research is done in a laboratory using cultivated cancer cell assays in petri dishes or well plates, it typically does not take interactions with other parts of a body into consideration, which is ultimately necessary for a patient to survive treatment without harmful side-effects. In order for a cancer treatment to be viable, it would have to primarily target only cancer cells; not healthy ones. Added to this is the issue that major cancer in the body quickly evolves resistance to most treatments, most treatments end up either unused or used as just one in a cocktail of cancer fighting drugs.
Here, Randall reminds us that there's no need to get excited upon hearing about a drug that kills cancer cells because it may very well harm healthy cells as well, just as a bullet fired from a handgun would.
The title text suggests that even if a drug did only kill cancer cells while leaving healthy cells alone, the human body still has many other complex processes that may render a drug that works in a petri dish insufficient. For instance, a drug that kills cancer cells in a petri dish may not be able to get at cancer cells deep within a human body. It is a long way from the laboratory to the pharmacy.
A more humorous interpretation of the title text is that it will only kill cancer cells if they are in petri dishes, and not anywhere else.
- [Caption above the panel:]
- When you see a claim that a common drug or vitamin "kills cancer cells in a petri dish",
- keep in mind:
- [Cueball in a lap coat stands on a chair next to a desk, pointing a gun at a petri dish. There is a microscope on the desk.]
- [Caption below the panel:]
- So does a handgun.
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One can test the cytotoxicity (the ability to kill cells) on a petri-dish level for cancer cells and healthy cells separately. However, this is often not done, knowingly neglecting selectivity issues one could face if the tests were done. This should be included in the explanation. The part that is written in the moment mainly explains the title text. 220.127.116.11 08:34, 27 May 2013 (UTC)
Sorry to correct you. Toxicity is tested for both, healthy cells an cancer cells. But as the targets for drugs are often present in both celltypes, the drug itself affect also both cells. Then you have to choose between certain death by cancer in short time and maybe death or side effects in the long row but survival. It's replacing one evil with another. Only very modern anticancer drugs (e.g. Gleevec) are selective enough to target (mostly) only cancer cells. The drawback is, as cancer in different people is not the same but different cells, you would need different drugs for everybodey affected. One way here lies in the personalized medicine, but that is very expensive...
18.104.22.168 10:05, 27 May 2013 (UTC)Richard
I've seen plenty of (academic, not industry) studies where tests on healthy cells were not done: The author present the synthesis of fancy new anti-cancer compounds XY, test it on HELA cells, see it is killing them, and publish this - even in high impact journals. This is a fact. 22.214.171.124 11:09, 27 May 2013 (UTC)
I am pretty sure this comic refers to the most recent overhyped headline of that type 'Vitamin C kills cancer cells'. Since it sounded like a natural remedy it was very widely spread, and widely misunderstood.126.96.36.199 11:38, 27 May 2013 (UTC)
Oxygen kills cancer cells! Under high enough temperatures it reacts with organic molecules in cancer cells, and produces CO2, H2O and some other stuff. --188.8.131.52 12:28, 27 May 2013 (UTC)
Read environmentalists-how-to-tell-the-bad-ones-from-the-good as analogous on how people commonly are unable to decipher scientific information. Spongebog (talk) 20:51, 27 May 2013 (UTC)
- Hey, that's "A Canadian-based monthly Christian magazine". Randall and me do not accept this!--Dgbrt (talk) 21:23, 27 May 2013 (UTC)
- Sure, we can just go with the Snopes  version instead ... Spongebog (talk) 21:31, 27 May 2013 (UTC)
- That April's fool is also a really old joke. "dihydrogen monoxide". H (hydrogen), two times - and O (oxygen) one time (mono...). My body and also yours too contains 60% of water. Any link to cancer? --Dgbrt (talk) 21:45, 27 May 2013 (UTC)
- They are both dangerous to your health Spongebog (talk) 03:18, 28 May 2013 (UTC)
- Dgbrt It would be "Randall and I do not ... " 184.108.40.206 20:10, 11 December 2013 (UTC)BK201
Actually, oxygen is quite toxic to all cells, even though our cells will quickly die without it. A very large proportion of our physiological pathways are involved in the two tasks of (1) using oxygen to meet the energy needs of our cells while (2) protecting our cells from its toxicity. Outside our cells also, oxygen is both essential and dangerous: much of our technology would not work without oxygen from the air, but that same oxygen creates a fire hazard.
220.127.116.11 12:16, 29 May 2013 (UTC)
I think supplements i hatethis blog post is particularly relevant to this article --Guru-45 (talk) 02:18, 9 September 2013 (UTC)