Lung Cancer Surpasses Stomach Cancer as the Leading Cause of Cancer Incidence

[Asia Economy Reporter Lee Chun-hee] Lung cancer has overtaken stomach cancer to become the most commonly occurring cancer in South Korea. This is the first time in 20 years since related statistics were compiled in 1999. The number of cancer patients diagnosed in a single year also exceeded 250,000 for the first time.

The Ministry of Health and Welfare and the Central Cancer Registry announced the 2019 National Cancer Registration Statistics on the 29th, which included this information. According to the data, a total of 254,718 new cancer patients were identified in 2019, an increase of 8,844 from the previous year. The cancer with the highest number of patients was thyroid cancer (30,676 cases, 12%). Lung, stomach, colorectal, and breast cancers followed.

However, thyroid cancer is a cancer that has sparked controversy over 'overdiagnosis.' Although it is relatively less dangerous and more like a tumor, it is diagnosed as cancer. Seo Hong-kwan, director of the National Cancer Center, explained, “According to the World Health Organization (WHO) report, 90% of thyroid cancers diagnosed in Korea are overdiagnosed.” The National Cancer Center issues separate statistics excluding thyroid cancer due to the confusion caused by this.

This is why lung cancer, with 29,960 patients, is considered the 'de facto number one.' This ranking surpasses stomach cancer (29,493 cases), which had been the most common cancer since 1999. Among men, lung cancer had the highest incidence even when including thyroid cancer. The order of common cancers in men was lung, stomach, colorectal, prostate, liver, thyroid, kidney, pancreas, bladder, and gallbladder/bile duct cancers. For women, breast cancer was the most common, followed by thyroid, colorectal, stomach, lung, liver, and pancreatic cancers.

The Central Cancer Registry attributed this reversal in ranking not to an increase in lung cancer but to a decrease in stomach cancer. Looking at the incidence rates per 100,000 people by cancer type, stomach cancer dropped significantly from 45.6% in 2009 to 30.8% in 2019, while lung cancer showed a similar trend, changing slightly from 28.9% to 28.2% over the same period. Won Young-joo, head of the Cancer Registration Statistics Department at the National Cancer Center, explained, “Thanks to the national cancer screening program, stomach cancer incidence has decreased as early-stage epithelial cancers are detected and treated in advance.” The inclusion of endoscopic screening in the national cancer screening program has enabled early detection of gastrointestinal diseases, leading to a simultaneous decline in stomach and colorectal cancers.

Lung cancer, which has a low 5-year relative survival rate (the probability of surviving more than five years compared to non-cancer patients) of only 34.7%, showed a notable increase among women. In 2019, 9,629 women were newly diagnosed with lung cancer, accounting for 32.6% of all new lung cancer patients. However, the majority of these women were non-smokers, a well-known risk factor for lung cancer. Many were likely affected by secondhand smoke exposure during childhood or inhaled smoke while cooking in the kitchen. Additionally, the recent rise in female smoking rates is also considered a risk factor.

If Koreans live to the average life expectancy of 83 years, the probability of developing cancer during this period is 37.9%. This means that 4 out of 10 people will develop cancer. For men, the probability is 39.9% if they live to 80 years, and for women, it is 35.8% if they live to 87 years.

However, the 5-year relative survival rate for cancer patients has shown a continuous upward trend. The 5-year relative survival rate for patients diagnosed with cancer between 2015 and 2019 was 70.7%, an increase of 5.2 percentage points compared to 65.5% between 2006 and 2010.

This content was produced with the assistance of AI translation services.