Despite a successful national screening program, the incidence of colorectal malignancies has not significantly decreased in recent years.

Colorectal cancer has been among the most common malignancies in Taiwan for more than a decade, and it has had a relatively high mortality rate. About 15,000 people are diagnosed with the disease in Taiwan every year, according to data compiled by the Ministry of Health and Welfare (MOHW).

Although colorectal cancer has a five-year survival rate of more than 90% if it is caught early, many cases in Taiwan are not detected until the cancer has spread to regional lymph nodes or worse, metastasized to distant parts of the body. In such cases, the five-year survival rate is just 14%.

Of all cases in Taiwan, about 50% involve distant metastasis, says Dr. Chiu Han-Mo, a clinical professor at National Taiwan University’s (NTU) College of Medicine and chief of the Health Management Center at NTU Hospital.

“Many people think that because they have no symptoms that they are not sick or that they do not have to worry about the disease because they have no family history of it. This is insufficient awareness,” Chiu says. 

He notes that colorectal cancer often causes no symptoms at its onset, which is why screening is such an important tool for fighting the disease. 70% of colorectal cancer cases are sporadic, and just 20% are directly related to genetic factors, he observes.

Chiu attributes the steady incidence of colon cancer in Taiwan to a sedentary lifestyle and unhealthy diet – high in red meat and carbohydrates – as well as an aging population. Life expectancy in Taiwan has risen steadily from about 55 in 1950 to more than 80 today.

“When people live longer, they become more susceptible to certain chronic diseases,” Chiu says. The mean age of colon cancer diagnosis in Taiwan is about 66 for both men and women, according to data from Taiwan’s Cancer Registry System.

Worryingly, younger Taiwanese are being diagnosed with the disease at an increasing rate, which dovetails with a global trend. Citing clinical observations, The Taipei Times noted in an August 2020 report that the incidence of colorectal cancer in Taiwanese aged 20-40 has risen about 20% in recent years.

Excessive use of antibiotics may have a detrimental effect on gut bacteria and could be associated with an increased risk of colorectal cancer, especially in younger people who have had greater exposure to the drugs than their elders, Chiu says.

New research presented at this year’s ESMO World Congress on Gastrointestinal Cancer that analyzed the data of 8,000 patients from a primary care database in Scotland found that the use of antibiotics was associated with an increased risk of colorectal cancer across all age groups. For patients under the age of 50, the risk increased by almost 50%, while for those older than 50, the increase was just 9%.

“Junk food, sugary drinks, obesity, and alcohol are likely to have played a part in that rise, but our data stress the importance of avoiding unnecessary antibiotics, especially in children and young adults,” Sarah Perrott, one of the study’s authors and a medical student at the University of Aberdeen, said during a presentation at the ESMO World Congress.

However, experts caution that it is too early to say whether use of antibiotics is a causative factor for colorectal cancer. “We need more scientific evidence before we can be more certain of what is causing the rise in colorectal cancer in younger people,” says Dr. Wang Jaw-Yuan, director of the Department of Medical Research at Kaohsiung Medical University’s Chung-Ho Memorial Hospital.

Preventative medicine

Fortunately, the availability of effective screening tools means that colorectal cancer is one of the most preventable malignancies. While a colonoscopy remains the gold standard for screening, there are other less invasive options that are also effective, such as a fecal immunochemical test (FIT) or fecal occult blood test (FOBT). Both tests look for microscopic traces of blood in a stool sample. Many pre-cancerous polyps or early-stage colorectal tumors bleed, but in amounts too small to be seen by the naked eye.

NTU’s Chiu notes that Taiwan’s national colorectal cancer screening program, introduced in 2004 and offering FIT on a biennial basis, has been effective at reducing late-stage disease and deaths. Participants identified as having a possible malignancy are referred for a follow-up examination, usually involving a colonoscopy. In the first decade of the screening program, cases of advanced disease fell 29%, while deaths fell 35%, he says. In addition, coverage of the eligible population (ages 50-75) reached more than 57% by 2014.

Screening has room for improvement, though, and education is key. One challenge is that Taiwan’s national health insurance does not cover the approximate NT$3,000 cost of sedation for the colonoscopy. “Some people think it is expensive and may hesitate to get the colonoscopy,” Chiu says.

Another challenge is that Taiwan has historically had a greater prevalence of upper gastrointestinal diseases, such as esophageal and gastric cancers. Thus, gastrointestinal training has focused more on those diseases than colorectal cancer. Given that colorectal cancer is now more prevalent in Taiwan, “training to increase the number of gastroenterologists who are competent to perform colonoscopy is an urgent task required to meet the future demand, and both the government and professional societies should more actively address this problem,” researchers wrote in the May 2018 edition of the Journal of the Formosan Medical Association.

Meanwhile, with colorectal cancer on the rise in younger people, Taiwan could consider reducing the minimum age of participants in its national screening program. In 2018, the American Cancer Society lowered the recommended age to begin colon cancer screening from 50 to 45.

The United States Preventive Services Task Force (USPSTF), an independent panel of volunteer medical experts, wrote in a May publication, “The USPSTF concludes with moderate certainty that screening for colorectal cancer in adults aged 45 to 49 years has moderate net benefit.”

Kaohsiung Medical University’s Wang says that reducing the minimum screening age may be under consideration in Taiwan. “There are certainly costs to doing it, but we have to consider that these people are in the prime of their lives and responsible for supporting their families,” he says.