Does Environment Affect Cancer Risk?


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When changes in genes occur, it affects the way cells function and this can lead to cancer. Some gene changes occur naturally during DNA replication, which happens nonstop throughout our lives. Some gene changes occur due to a genetic predisposition (or inherited syndrome). More specifically, 20-30% of colorectal cancers are familial, 5-10% of colorectal cancers are hereditary in nature, and 60-70% of colorectal cancer is sporadic. Sporadic cancer means that a person starts out with healthy genes in their cells and genetic mutations accumulate over time (typically due to age, environment, and other factors). Examples of environmental carcinogens could include certain chemicals, for example, or foods we eat, etc. Perhaps some of the most commonly known environmental factors affecting risk of cancer are the use of tobacco, which contains a high number of carcinogens (cancer causing chemicals), and the radioactive gas radon.

Poor environmental quality and cancer

In a May 2017 study published in Cancer (the American Cancer Society’s peer-reviewed journal), it was suggested that exposure to overall poor environmental quality could increase cancer risk. The study was led by researchers at the University of Illinois, Chicago. The research team looked at data from The Environmental Protection Agency (EPA), The Environmental Quality Index (EQI), and cancer incidence rates from the Surveillance, Epidemiology, and End Results (SEER) Program state cancer profiles to see if there was any type of relationship. The EQI includes the following 5 measures for environmental quality:
  • Air
  • Water
  • Land quality
  • Sociodemographics
  • Built environment (man-made surroundings like buildings, parks and bike lanes)
The results of the study showed, for men and women equally, areas with poor environmental quality had a higher incidence of cancer cases versus counties with higher environmental quality. The findings were even more pronounced for prostate and breast cancers.
On average, counties with poor environmental quality had nearly 40 more cancer cases per 100,000 people than counties with higher environmental quality.
Of the areas researched, it was seen that the more urbanized the county, the more vulnerable to cancer risk the residents were, though there were no differences based on region of the country. It’s important to note this study did not account for things like obesity, smoking or other comorbidities (multiple chronic diseases) within the counties involved. Many comorbidities such as smoking and obesity are also known factors that increase cancer risk, and the rates of these and other factors were not taken into account within the counties surveyed in the study. There are many studies that have assessed particular carcinogens in the environment to learn about how they affect the risk of cancer (for example, studies on radon, arsenic, and others), however, the approach of the current study uses a broader environmental lens to see a broader picture of how the environment could be affecting our health. (If you’re interested in gathering colorectal cancer data on the area that you live, check out our blog on how to find state specifics for tips and links!)

What does this mean for colorectal cancer and prevention?

We often think “if we change this one thing, cancer won’t happen.” For example, when bacon was a hot topic last year, many people cut it out completely from their diets. However, reducing cancer risk may be far more complicated than removing just one component. There are many elements at play when it comes to cancer risks- family genetics, diet, exercise, stress, and environmental exposures, like the air we breathe. While we can control some of these things, like what we eat and how much we exercise, we can’t control it all. Acknowledging the many contributing factors to cancer risk is important because it allows researchers and doctors to truly look at the whole patient and consider their overall environmental health in addition to their physical health as they both affect a person’s wellness. The results of the study perhaps indicate the need for improved social and environmental conditions and the need for organizations like the EPA to continue conducting research to learn about how the environment affects our health while using these data to support guidelines that will improve health conditions for all. To that end, it is important to encourage our representatives in Washington, D.C. to support environmental protections in whatever way they can. (If you've not yet, register as an advocate!)
The overlap between the environment and population health is evident, and perhaps some lives could be saved if environmental health was improved.
We look forward to learning more about the role the environment plays in colorectal cancer risk and prevention and will update you as we know more.

Get More Information

While we cannot control the environment, we can control and reduce some of our colorectal cancer risks. Get more resources on nutrition, exercise and screening. Also, sign up to receive the latest news in your inbox! References: “County-level cumulative environmental quality is associated with cancer incidence.” Jyotsna Jagai, Lynne Messer, Kristen Rappazzo, Chris Gray, Shannon Grabich, and Danelle Lobdell. CANCER; Published Online: May 8, 2017 (DOI: 10.1002/cncr.30709). National Cancer Institute:

One thought on “Does Environment Affect Cancer Risk?

  1. This is very helpful article ever, some of the most commonly known environmental factors affecting risk of cancer are the use of tobacco, which contains a high number of cancer causing chemicals, and the radioactive gas radon.

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