Thursday, October 22, 2009

Incomplete Reversal of Barrett's Esophagus

Does ablation of non-dysplastic Barrett's esophagus make sense?

According to one recent study and another ten-year old study, squamous islands, created during the incomplete ablation of Barrett's esophagus, may still be genomically unstable and prone to carcinogenesis.

The creation of squamous islands (i.e., islands of normal esophageal cells in the sea of Barrett's esophagus cells) can occur as a result of prolonged PPI therapy. The simplest hypothesis is that normal squamous cells grow over or grow out from under the Barrett's cells once conditions in the esophagus return to normal due to acid suppression. The potential creation of squamous islands is promoted as one of the successes of PPI therapy.

However, a study way back in 1999 found that these squamous islands possess abnormal biomarkers (e.g., Ki-67, p53 abnormalities) that suggest genomic instability and continued risk for cancer progression. I am not aware of any follow up studies showing that such squamous islands progress to cancer at higher rates than other tissue, and suspect the implications of this finding are not fully understood yet.

Interestingly, the recent study cited above showed that incomplete photodynamic abaltion produces similar results -- abnormal biomarkers, including Ki-67, cyclooxygenase-2 (COX-2), and p53 staining.

The moral of the story is that if you get photodynamic therapy, don't be one of the 30%-50% of people whose doctors do it wrong... The more serious moral of the study, is that it might not be a good idea to get photodynamic ablation unless you already have dysplasia.

I just don't know whether the 1999 finding is a good enough reason to stop PPI therapy. I guess I have some faith that, since this has been known for 10 years, somebody would have noticed if those "lucky" people with squamous islands were dropping dead faster than those without. Perhaps the abnormal biomarkers are just a temporary sign of genomic instability in the good sense -- i.e., caused by the reversion to neo-epithelial cells -- and not a genomic instability that leads to cancer?

In any case, I suspect that eating and supplementing in a manner that promotes genomic stability should help. Vitamin D seems to be one powerful weapon in this fight. There are others that I will discuss in future posts.

Image from here.

Tuesday, October 13, 2009

Pure L-Theanine

As I mentioned in an earlier post, theanine, an amino acid found in green tea, should help reduce reflux by increasing GABA levels in the central nervous system. Because green tea also has caffeine, which inhibits GABA release, I decided to take pure L-theanine, available in pill form, to see if it would help my reflux.

I took 100mg L-theanine about 5 times (when I had reflux) over a period of two weeks. I stopped the experiment early because L-theanine seems to make me anxious and/or give me heart palpitations. It's not supposed to do that at all, so I'm not sure it wasn't just coincidence or imaginary. But, to be safe, no more L-theanine for me. Besides, based on my limited experience with it, I don't think it helped my reflux that much.

I'm going to move away from anti-reflux measures for a little while to focus on some core Barrett's esophagus chemopreventation strategies. I will return to anti-reflux measure after I complete a few more experiments. Stay tuned.

Wednesday, October 7, 2009

Does Reflux Matter?

Most cases of esophageal adenocarcinoma start with Barrett's esophagus and most cases of Barrett's esophagus start with reflux. Does it follow that stopping reflux can halt the cancerous progression of Barrett's esophagus? I'm not so sure.

As you would expect, reflux isn't made up of just acid. It includes partially digested food, bacteria, stomach acid, and bile, among other constituents. And, it seems that both acid and bile reflux play important roles in the development of Barrett's esophagus.

It is not as clear that reflux causes Barrett's esophagus to progress to cancer as it is that reflux causes Barrett's esophagus to develop in the first place. For example, surgical correction of the lower esophageal sphincter doesn't seem to be better than acid suppression at reducing the risk cancer in people with Barrett's esophagus. Likewise, consumption of substances, like alcohol, that increase reflux don't seem to be significantly associated with the progression of Barrett's esophagus to cancer. On the other hand, excessive consumption of alcohol in early-life (presumably before the development of Barrett's esophagus) is strongly associated with having Barrett's esophagus later in life.

One manner in which reflux may contribute to the cancerous progression of Barrett's esophagus is by causing damage to the esophagus that results in chronic inflammation. Acid suppression seems to reduce this chronic inflammation, which is why I take a PPI every day. There are different viewpoints on whether acid suppression is cost-effective chemoprevention for esophageal adenocarcinoma - for example, see this. Having studied both sides of the debate, I suspect it's wise to suppress acid at least enough to control chronic inflammation. Unfortunately, there have been no placebo controlled trials on the efficacy of PPIs for chemoprevention of esophageal adenocarcinoma, so we don't know for sure and are unlikely to know for some time.

Beyond contributing to chronic inflammation, I suspect that reflux plays a relatively minor role in the progression of Barrett's esophagus to cancer. Instead, my guess is that once a person gets Barrett's esophagus, the Barrett's cells that have formed are on march towards cancer that is principally modulated by (i) inflammation, (ii) diminished genetic stability/cellular adhesion, and (iii) poor immune response.

That said, I still worry about reflux for three reasons:

1. Since I only have short segment Barrett's esophagus (about 1 cm), there are still many more cells in the vicinity of my dysfunctional LES that could "go rogue" (i.e., become Barrett's esophagus cells). Since the the chance of progressing to cancer seems to depend, to some extent, of the amount of Barrett's cells one has, I would like to have fewer Barrett's cells if possible.

2. Acid suppression doesn't do much to prevent bile reflux, and bile reflux may contribute to inflammation.

3. There's a chance that reflux is a player (beyond its effect on inflammation) in the progression of esophageal cancer after all.

Tuesday, October 6, 2009

Green Tea; Theanine, Caffeine, and GABA

Among its many health benefits for people with Barrett's esophagus, green tea also seems to reduce reflux by tightening the lower esophageal sphincter. Green tea's effect on reflux is caused by the caffeine and theanine in it, both of which affect the CNS control of the LES. Caffeine decreases the amount of GABA in the Vagus nerve while theanine increases the amount. More GABA in the Vagus nerve produces a tighter LES, and a tighter LES produces less reflux. Since the theanine in green tea has a more potent effect on GABA than caffeine, green tea should, in general, reduce reflux. Indeed, it does just that for me.

Since caffeine undoes some of theanine's good deeds, it might be nice, especially at night, to brew a cup of high-theanine, low-caffeine tea. I know that most of the caffeine is released from tea leaves in the first 30 seconds or so, but I can't find reliable information on the release of theanine from tea leaves. Decaffeinated green tea may offer a solution as it seems that supercritical CO2 decaffeination (a method used for all organic decaf green teas), leaves in most of the theanine. Also, I believe there's more theanine in high quality loose leaf tea than in teabag tea, so I would generally recommend loose leaf teas.

A post on theanine supplements coming soon....