Rising bladder cancer cases in Korea prompt concerns, experts warn

The number of patients developing bladder cancer, an organ that stores urine produced by the kidneys, has increased significantly in Korea. Experts warn that this number may continue to rise in the future.

According to the Korean National Cancer Registry, the number of bladder cancer cases in 2021 was 5,169, an increase of about 45 percent compared to 3,553 in 2010, said Professor Kim Kyung-hwan of the Department of Urology at Pusan National University Hospital on the YouTube channel of the Korean Urological Oncology Society.

"Not only in Korea, but also overseas, such as in the U.K. and the U.S., the number of bladder cancer cases is rapidly rising," said Koo Ja-yoon, head of the Urology Department at the Dongnam Institute of Radiological & Medical Sciences (DIRAMS). He warned that the incidence of bladder cancer will continue to increase in the future.

What is bladder cancer?

The bladder, the lowest of the abdominal organs, is made up of muscle cells that stretch easily, resembling a thin, elastic balloon. It is composed of four layers: mucosa, submucosa, muscle, and fat. The mucosa, which comes into direct contact with urine, is covered with urothelial cells.

"Bladder cancer is a malignant tumor that occurs in the bladder," explains Professor Lee Chan-ho of the Department of Urology at Busan Paik Hospital. "Bladder cancer is mostly caused by urothelial cells, so when we say bladder cancer, we usually mean urothelial cell carcinoma."

Bladder cancer is not limited to urothelial cells. "Bladder cancer is classified into urothelial cell carcinoma, which is derived from urothelial cells that come into direct contact with urine, and squamous cell carcinoma and adenocarcinoma," Koo said. "Of these, urothelial cell carcinoma accounts for 95 percent, squamous cell carcinoma for 3 percent, and adenocarcinoma for less than 2 percent."

Even within the same type of bladder cancer, the treatment prognosis for urothelial cell carcinoma, squamous cell carcinoma, and adenocarcinoma varies, he went on to say.

"In general, squamous cell carcinoma and adenocarcinoma are known to have a poorer prognosis than urothelial cell carcinoma, which is more common."

Cause of bladder cancer

Currently, the cause of bladder cancer has not been clearly identified, but there are several known risk factors, according to Professor Kim. 

“Age, smoking, chemical exposure, infections, and bladder stones are among the major risk factors,” he said.

One of the factors contributing to the increase in bladder cancer in Korea is the aging population. Bladder cancer is characterized by an age-related increase in incidence, with 8 out of 10 patients over the age of 60, and it is particularly aggressive in men. 

The strongest risk factor for bladder cancer identified to date is smoking.

"Current smokers have a 1.6 times higher risk of developing bladder cancer than the general population, and former smokers have a 1.3 times higher risk of developing bladder cancer than the general population," Kim said.

Occupational exposure to chemicals in the production of paints, dyes, iron, and petroleum also increases the risk of bladder cancer. 

"However, in this case, the risk can be reduced by following safety rules in the workplace,” Kim said.

In addition, chronic cystitis is also known to increase the risk of developing bladder cancer. Family history also plays a role; if you have an immediate family member with bladder cancer, your risk of developing bladder cancer increases.

"Whether this is due to genetics or environmental factors, such as shared living conditions, is not yet known," says Dr. Koo. "In particular, squamous cell carcinoma is known to be associated with bacterial infections and bladder stones."

About 70% of bladder cancers are non-muscle invasive at first diagnosis

Bladder cancer is categorized into three main stages, depending on its advancement, according to Professor Lee. 

It includes non-muscle-invasive bladder cancer, also known as superficial bladder cancer, which means the tumor has not invaded the muscle layer of the bladder, muscle-invasive bladder cancer, and metastatic bladder cancer.

About 70 percent of all initially diagnosed bladder cancers are non-muscle-invasive. While metastasis to other organs is relatively rare compared to muscle-invasive bladder cancer, there is a risk of recurrence and progression, Lee said.

Unlike non-muscle-invasive bladder cancer, muscle-invasive bladder cancer refers to cases where the tumor has deeply penetrated and invaded the muscle layer of the bladder, which lies beneath the bladder mucosa. It is termed 'metastatic bladder cancer' when it spreads to other organs such as the liver, lungs, or lymph nodes.