Thursday, March 2, 2017

HPV and colon cancer

NYTimes: There is an increase in colon cancer in the young.

Obesity and sedentary lifestyles are also associated with colorectal cancer, as are heavy alcohol use and chronic conditions like inflammatory bowel disease and Type 2 diabetes, all of which are on the rise. But experts are not entirely convinced these are the only reasons colorectal cancer is increasing among young people. While rates of cancers tied to human papillomavirus, or HPV, have been rising in recent years, that virus causes mainly cancers of the cervix, anus or the back of the throat, and only a small number of cases of rectal cancer.

there are three types of colon cancer: anal cancer, which is known to be partly caused by HPV, Rectal cancer, which clinically has become a lot rarer since I started in medical school, and colon cancer, which seems to be about the same.

I've never seen an Anal cancer, which is associated with HPV. However, we did have a family cluster of genetic colon cancer in ourObjibwe patients. However, colon cancer is more common in Black Americans (and west Africans, but interestingly enough not in the South or East Africans, who eat a high fiber diet, hence the push for fiber).

We used to be urged to do rectal exams to find rectal cancer back in the 1960's, but you know, I hadn't seen any cases in the last ten years I worked. For some reason (diet?) most of the cases went upstream, and so routine sigmoidoscopies stopped being urged and routine colonoscopies, which were harder to do and mainly done by experts, took their place.

Instapundit wonder if anal sex is part of the reason. and lots of comments there.

So what does the NYT say?

t found that in adults ages 20 to 39, colon cancer rates have increased by 1 percent to 2.4 percent a year since the mid-1980s, while rates declined over all among those 55 and older. Rates among adults 40 to 54 increased by 0.5 percent to 1.3 percent a year since the mid-1990s.
Rectal cancer incidence rates among adults in their 20s increased even more sharply, rising by 3.2 percent a year from 1974 to 2013. And while rectal cancer rates have declined over all among people 55 and older since 1974, rates in people 50 to 54 increased between 1989-90 and 2012-13. 
 By 2012-13, nearly 30 percent of all rectal cancers were being diagnosed in people under age 55, compared with 15 percent of all rectal cancers being found in this age group in 1989-90, the study reported.

epidemiology suggests diet is a large part of the problem link 

the NYT and studies above are only doing 30 year comparisons. I date back 45 years which is why my comments are slightly different, and of course most of my work was with poor whites/Hispanics in rural area or with AmerIndians, so genetically different and different diets.

But the rate hasthis cancer has changed in the last century:

Before the 1900s, colorectal cancer was relatively uncommon in the U.S., but its incidence rose dramatically over the last century in parallel with economic development. Worldwide, the majority of colorectal cancers continue to occur in industrialized countries, although incidence rates are rapidly rising in less-developed nations as they increasingly adopt features of a Western lifestyle. Migration studies also demonstrate a higher lifetime incidence of colorectal cancer among immigrants to high-incidence, industrialized countries compared to residents remaining in their native, low-incidence countries. Taken together, these data highlight the importance of environmental influences on colorectal carcinogenesis. 

one of the interesting findings mentioned in the article is that Aspirin and NSAID use is associated with a lower rate of colon cancer. LINK2

I am not sure wat to make of the NYT article about young cancers, i.e. under age 50. HPV? Diet? Chemicals in the environment?

There actually has been a decrease in eating fat in the US population, as evidenced by the lowering of heart attack/ASCVD. So is it the type of fat?

Complicated problem.

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