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For journal club last week, I selected an article that looks at length of telomeres as a prognostic variable for prostate cancer. Telomeres are DNA protein complexes that are added to the tips of chromosomes by an enzyme, telomerase, that carries its own little RNA unit and was involved in one of the authors (Elizabeth Blackburn) of the story below winning a Nobel prize. As you get older, the length of your telomeres shortens, eventually giving rise to loss of important chromosomal information that can lead to cancer. In the journal club article, it was found that men who had shorter and more variable telomere length in their prostate cancer or the surrounding tissue, had a higher chance of developing metastases or dying from their disease. Of course this is bad news, and you might think there is nothing you can do about it. Not so fast….
Blackburn and her colleagues at UCSF have been studying men with prostate cancer to see if exercise and diet can influence telomere length. In a 2008 study, they found that peripheral blood cells had increased telomerase after 3 months of improved diet and exercise intervention. In their most recent study, they find that the continuation of the diet/exercise program results in actual increases in the telomere length in the peripheral blood cells. Since these are men with low risk prostate cancer who are being followed on a study with active surveillance, we will also be learning how such improved life style affects other genetic changes in serial biopsies of the cancers.
For now, the bet is that (as usual) you will benefit from increasing your exercise program, dropping red meat from your diet, and probably watching less football and doing more hiking this week with your family as you celebrate Thanksgiving. I’m just saying….
When I was a kid, my father, having grown up on a farm, was obsessed with having me drink lots of milk. There was a milk delivery service in Chadron, NE, that brought rich, fresh, whole milk to our door, and I recall drinking at least a gallon a week – sometimes twice that. I was told it would “build strong bones and healthy teeth”, especially during my pubertal years, when there is of course a growth spurt that does indeed require more calcium and good nutrition. (Hence the increased height of American children over the past century…)
But there is a dark side to this story. In an article in Medscape today, there is a lovely review of another pathway that stimulates prostate cancer, namely one that involves the PI3K-Akt-mTORC1 pathway. It is way beyond this blog to try and go into this pathway in any detail, but suffice it to say that the authors present a powerful (albeit very long) argument that leucine, a branched chain amino acid found in high concentration in cow’s milk stimulates this pathway and can lead to prostate cancer growth and metastases. I will reproduce here (and without permission….I wonder if that is needed in the blog world…) a couple of the figures that illustrate the point. (note I am not plagiarizing since I give you the link to the original article containing these figures)
This figure illustrates how leucine interacts with the signaling pathways that might lead to prostate cancer or stimulate its growth.
This figure demonstrates the increased consumption of milk products like cheese and milk that have occurred over time in western countries.
The bottom line here is that milk and cheese have a dark side and we should probably curtail our intake, especially in families who have high prostate cancer rates. It would be nice to go into all 250+ articles the authors cite, but trust me, their arguments are very well founded. Too bad, since I love cheese so much !
When you go through the screening systems at our national airports, there are often videos that describe the process, reminding you to take any liquids out of your suitcase and so forth. I think it is time for cancer centers (and others) to do the same thing at their annual screening events for breast, prostate and other cancers. I have no problem with participating in screening events if the participants are fully informed about the benefits, risks, and the controversies surrounding screening for prostate cancer. However without such information, I fear that most men simply open Pandora’s box without really knowing what they are getting into. Does a 75 year old man realize that his chances of dying from prostate cancer are tiny compared to the other lurking causes of death? Does a 60 year old man understand that a Gleason 6 cancer can be followed safely with active surveillance, but that it will require “life long” repetitive biopsies? The NEJM article on this issue this week is worth everyone reading. Marketing should not be what medicine is about.