[Reading Science] Smoking Decreased but Lung Cancer Remains 'Number 1'... What’s Happening?

Westernized Korean Bodies and Rapid Changes in Cancer Maps
Decline in Stomach and Liver Cancer, Sharp Rise in Lung, Prostate, and Breast Cancer
Population Aging Makes Those Over 65 the Primary Risk Group for Lung Cancer

As the dietary habits and physical conditions of Koreans become more Westernized, the trends in cancer incidence are also changing. While stomach and liver cancers are decreasing, there is a clear trend of increasing Western-type cancers such as lung, breast, and prostate cancers. In particular, despite a decline in smoking rates, lung cancer has effectively become the most common cancer among Koreans due to population aging and increased air pollution, highlighting the urgent need for countermeasures.

Looking at cancer types individually, stomach cancer dropped from 2nd place in 2010 to 4th place in 2020 based on incidence. Liver cancer also fell from 5th to 7th place during this period. However, Western-type cancers, specifically lung cancer, rose from 4th to 2nd place. Thyroid cancer, which ranked 1st during this period, has been subject to controversy over “overdiagnosis” due to advances in screening technology diagnosing relatively less dangerous tumors as cancer. This means lung cancer has effectively become the most common cancer among Koreans. Additionally, breast and prostate cancers each moved up one rank, from 6th and 7th to 5th and 6th, respectively. Over the past decade, prostate cancer increased by 109%, breast cancer by 112%, and endometrial cancer by 85%, nearly doubling their incidence rates.

The decrease in stomach cancer incidence is attributed to a lower Helicobacter pylori infection rate and the Westernization of dietary habits. In particular, the widespread use of national screening endoscopy has greatly contributed to the reduction by enabling rapid detection and treatment of stomach-related diseases. Liver cancer and cervical cancer are also on the decline due to increased vaccination, safer sexual practices, and changes in eating habits such as serving food individually.

On the other hand, Western-type cancers are rising sharply. Lung and colorectal cancers are mainly attributed to population aging. The lung cancer incidence rate among those aged 65 and older is 1,480 per 100,000, making it the most common cancer overall. Lung cancer surpasses stomach and colorectal cancers in incidence. Particularly among men, lung cancer incidence is high in the elderly with a history of smoking. Smokers have a 15 to 80 times higher risk of developing lung cancer compared to non-smokers, and exposure to secondhand smoke increases the risk by 1.2 to 2 times. Lung cancer is also common among women, rising from 5th to 4th place in cancer rankings over the past decade. Although 80% of female lung cancer patients are non-smokers, cooking fumes inhaled during food preparation and secondhand smoke are the main causes.

Prostate cancer increased by 109.2% compared to 2010, ranking as the third most common cancer among men after lung and stomach cancers. This is due to dietary changes involving higher consumption of animal fats and meat. Breast cancer has continuously ranked first among major cancers in women since 2016, increasing sharply by 112.1% from 2010 to 2020. Factors contributing to breast cancer include longer exposure to female hormones (early menarche and late menopause), lack of childbirth or breastfeeding, late-age childbirth, and alcohol consumption.

Endometrial cancer (mainly uterine body cancer) was outside the top 10 in incidence until 2015 but increased by 85.7% over ten years to rank 8th among female cancers. Causes include overweight due to high-calorie intake, an increase in the postmenopausal population, and increased use of hormone replacement therapy. Notably, endometrial cancer was the first cancer found to be associated with obesity. Obesity increases the risk of endometrial cancer by 2 to 11 times.

The increase in Western-type cancers is closely related to obesity caused by fatty diets and lack of exercise, as well as population aging. According to the National Health and Nutrition Examination Survey released by the Korea Disease Control and Prevention Agency in March this year, the prevalence of obesity (waist circumference) increased across all age groups from 2011 to 2021. In particular, adult males nearly doubled from 27.2% in 2011 to 40.3% in 2021.

Experts recommend balanced meals, consumption of fresh vegetables and fruits rich in dietary fiber and vitamins, walking or exercising for at least 30 minutes five times a week to maintain weight, quitting smoking and drinking, and undergoing regular health check-ups.