Good economy? More bowel cancers, study finds

Story highlights

  • Study reveals higher rates of colorectal cancer in more developed countries
  • Increased disparity has led to a 10-fold difference in numbers of cases worldwide
Vital Signs is a monthly program bringing viewers health stories from around the world.

(CNN)Economic development is a good thing -- but not when it comes to the risk of developing colorectal cancer.

According to a recent study, as a country develops, rates of this type of cancer rise alongside it.
    The study revealed a 10-fold difference in cases worldwide, based on a country's level of economic development. The "western" lifestyle that comes with a country's growing economy is thought to be behind the increase in rates.
    "Colorectal cancer is the clearest marker of societal and economic transition," says Cancer epidemiologist Melina Arnold, from the International Agency for Research on Cancer, who led the study.
    Also known as bowel cancer, it's the third most common type of cancer in the world. It affected 1.4 million people in 2012 and is predicted to increase by 60%, to more than 2.2 million cases -- and 1.1 million deaths -- by 2030.
    This form of cancer is a common result of poor lifestyle choices such as a bad diet, low levels of exercise, smoking and drinking excessive alcohol.
    "[It] is largely preventable because it's related to lifestyle factors," says Arnold.
    Arnold and other experts in the field were already aware of the geographical variation seen in rates of this cancer specifically, but its extent came as a revelation.
    "There is a widening disparity," says Arnold.

    Does prosperity lead to cancer?

    Arnold's team analyzed rates of colorectal cancer across all levels of the Human Development Index (HDI) in 184 countries and found that the higher the HDI, the higher the rates of bowel cancer. Countries with a very high HDI had levels, on average, six time higher than countries with a low HDI.
    More importantly, this type of cancer was found to be on the rise in low and middle-income countries as their economies develop.
    "Decades ago you didn't see so much of it in low-income countries, there were more infection-related cancers," says Arnold.
    One example of an infection-linked cancer is cervical cancer, which can result from infections with Human Papilloma Virus (HPV).
    But today, lifestyle diseases -- and cancers -- are making more of an appearance.
    "Low income countries are catching up," she says.
    Countries where colorectal cancer numbers -- and death rates -- were on the rise, or stable, include China, Russia, Brazil and the Baltics, which have all undergone rapid economic development over the past decade. With this change comes rapid progression to a western diet and lifestyle.
    The study was observational, with findings based on populations aging and living longer, but experts have long known the role of lifestyle in the onset of this form of cancer.

    Lifestyle and cancer

    "There is a prominent role of diet and lifestyle in this cancer," says Amanda Cross, Assistant Head of the Cancer Screening and Prevention Group at Imperial College London.
    Cross researches the role of red meat and processed meats in the development of this form of cancer. "Those that consumed the most meat did have a higher risk," says Cross. This finding was again observational.
    Excess consumption of red meat, however, often comes with other poor lifestyle choices that also impact the chances of developing this cancer. "People who tend to eat the most red meat tend to be more overweight and are less active," says Cross.
    Men are at greater risk of the disease, but reasons for this trend are not fully understood.

    How it develops