Wednesday, February 9, 2011

Finally a Good Trade-off for Allergies

There's a cool new study out showing an inverse correlation between the intensity of your allergies and the susceptibility of getting gliomas, a common type of brain and spinal cancer.  Although it's just a correlation, the study supports other data suggesting that the more allergies you have the less likely you are to get certain types of cancer.  It's still uncertain as to why this might be the case, but one likely hypothesis is that allergies indicate an overactive immune system.  Cancers result only when your body fails to kill the rogue cells before they get out of control - if people with allergies have overactive immune systems, perhaps their bodies just make it naturally harder for cancer cells to escape and survive immune stimulation.  Perhaps further research will confirm or refute this hypothesis, and inform us of more handy tools we could make to block cancer formation.

Until then, take a look at this MRI image of a glioma taken from the Mayfield Clinic website:

4 comments:

Jonathan said...

Sorry that I'm still trolling your site. Worldviews aside, this is interesting to me from purely knowledge standpoint. Maybe you can enlighten me as I have no medical/biological background.

I am diagnosed with Crohn's disease which, to my understanding, means my immune system is overactive and "attacks" the tissue of my own colon and intestines. However, my understanding is that I'm at increased risk for colon cancer, due to the diagnosis.

I don't know if this is the same mechanism as allergies. I also have seasonal, nasal allergies, too. Would your hypothesis be true, that will maybe be good news for me.

Any thoughts?

Cookulacrates said...

No worries - I like the traffic and I promise to respond to your previous post, I just haven't had the time to write what I want to yet.

As for the allergies, I also have seasonal allergies, which is what this study is referring to. The tricky part is the correlation - we assume that whatever causes more allergies also prevents cancer formation (in general), but it could be that whatever increases cancer formation decreases general allergies. Right now we don't know completely, but the most favorable hypothesis is that your immune system is overactive in allergies (we know this), and we know that cancers occur because they find ways to avoid your immune system. The average person would die from cancer much earlier in life if it weren't for our fantastic immune systems. Every time someone gets sunburned but doesn't get skin cancer, or smokes a cigarette and doesn't get lung cancer, it's because their immune systems are good at identifying the cells that are being damaged and eliminating them before they get out of control. Perhaps in the future we'll be able to determine if the hypothesis that overactive immune systems causing allergies are good at fighting cancer is true.

Your individual case with Crohn's disease is a bit different - unfortunately Crohn's disease is a chronic condition of extreme inflammation and immune activity in the colon. While, in the case of allergies a heightened systemic immune reaction that keeps you stuffy all the time doesn't do any real harm, severe immune reactions at acute locations in your body causing inflammation actually destroys tissues and can cause mutations in cells that will ultimately result in cancer. So for you, the risk of colon cancer is higher because the tissue is always being agitated and attacked, whereas heightened allergies attack *foreign* objects, not yourself.

Jonathan said...

That's interesting. My maintenance therapy is a Remicade (Infliximab) infusion every 8 weeks. According to Wikipedia it's a tumour necrosis factor alpha inhibitor, which evidently plays a role in the immune system, but I don't know anything about that mechanism.

One of the side-effect risks of Remicade is lymphoma and solid tissue cancers. So maybe this too supports your hypothesis, that by inhibiting TNF it prevents my immune system from being as effective against certain cancers - resulting in the risk.

Cookulacrates said...

That's right! Tumor necrosis factor (as the name implies) is a molecule that ultimately is part of a response that recognizes necrotic (dying) tumor cells/debris and signals to the immune system to act and fight. Because your immune system is overactive the doctors have prescribed a drug (Remicade) that essentially blocks this process. As you correctly hypothesize, the consequence is that your immune system is weaker to fight other sorts of cancer by blocking the TNF response pathway, but your body will also stop attacking your colon - it's a trade-off that's usually better for you though. While I'm not specifically familiar with Remicade, it seems that you've got a good idea on how it works in a global context.