Higher than Usual Lung Cancer Incidence in Taiwanese Non-smokers  

On World COPD Day, the Ministry of Health and Welfare and physicians specializing in pulmonary diseases called on the public to refrain from smoking and to guard against kitchen fumes. Photo: CNA

An ongoing study suggests environmental factors in Taiwan are contributing to a rising number of cases in otherwise healthy non-smokers.

 After four doctors at National Taiwan University Hospital (NTUH) had suddenly collapsed on the job during the previous two years – with one of them failing to recover – the hospital in the second half of 2013 ordered all staff physicians 45 years of age and older to take a physical examination.

The comprehensive health checks included low-radiation computerized topography (CT) scans of the lungs. The results were chilling. Of 300 physicians tested, 12 (4%) were found to have a small lung nodule (less than 1 centimeter), which subsequent testing confirmed as lung carcinoma.

Among the most lethal of all cancers, lung carcinoma has a five-year survival rate of just 18%. The disease is the most frequent cause of cancer deaths globally, estimated to be responsible for about 1.59 million deaths worldwide (19.4% of the total) in 2012, according to the International Agency for Research on Cancer (IARC) under the World Health Organization (WHO).

NTUH oncologists were shocked at the results of the health exams. The doctors with lung carcinoma were all non-smokers and in good health. They had no symptoms of lung cancer, such as a persistent cough, chest pain, or difficulty breathing. None had a history of lung disease. Fortunately, all of the tumors were Stage 1A or 1B, the earliest phases of lung cancer when the disease is localized and can still be cured by surgery.

The hospital’s oncology team moved swiftly to perform lung resections on all 12 doctors. The operations were successful and all of the doctors are alive, cancer-free, and in good health today, says Dr. Wang Ming-jiuh, an NTUH anaesthesiologist and a former vice president of the hospital.

The detailed image of the lungs provided by the CT scan was crucial in detecting the tumors. In Stage 1, lung tumors do not usually show up on an x-ray, the type of lung screening used in most health checks. “A chest x-ray sometimes gives non-specific results; it’s unlikely to show a tumor smaller than 1 centimeter or if its location is shadowed by the cardiovascular system or bony structure,” says Kevin Chueh, the Oncology Medical Lead in Taiwan and Regional Director of Medical Affairs for pharmaceutical manufacturer Merck Sharp & Dohme (MSD).

That lung cancer was found in 4% of those who had the CT scan at NTUH is considered cause for concern, as it suggests that the disease is prevalent in non-smokers here.

Taiwan currently has about 10,000 lung cancer patients, equal to 0.004% of the island’s 23 million people – just 1/100th the prevalence of NTUH’s sample. Most of the existing cases are advanced – Stages 3 and 4 – when the disease is often terminal and when it is most likely to become symptomatic. There could be many more undiagnosed cases, Wang says.

In fact, he notes, NTUH was not the only hospital to discover early-stage lung cancer in otherwise healthy physicians. “A lot of other Taiwanese hospitals had similar findings” but did not publicize it “to prevent people from panicking,” he says.

Subsequently, the Ministry of Health and Welfare’s Health Promotion Administration (HPA), the Taiwan Lung Cancer Society, and the National Health Research Institute in 2014 jointly launched an eight-year study of Taiwanese non-smokers considered to be at high risk of developing lung cancer. Risk factors include a family history of lung carcinoma, exposure to second-hand smoke in the home, a history of chronic obstructive pulmonary disease (COPD) or tuberculosis, and chronic exposure to cooking fumes.

The study focuses on people aged 55-75, the age range when lung cancer is typically diagnosed. Up to 12,000 people are expected to participate.

Through August 2017, 7,664 participants in the study underwent CT scans for lung cancer. Malignant tumors were discovered in 175 people, or 2.28% of the total participants. Of the malignancies, 98% were early-stage (1A or 1B) adenocarcinoma, a type of non-small cell lung (NSLC) cancer that arises from the bronchi, bronchioles, and alveolar cells in the lungs. Adenocarcinoma is the most common type of lung cancer afflicting women, non-smokers, and younger men.

Not just a smoker’s disease

The study on lung cancer in non-smokers is groundbreaking because it highlights the risk that the disease poses to the wider population. For decades, lung cancer has been associated almost exclusively with cigarette smoking. With that association comes a stigma – that smokers have chosen to use a harmful substance and that the onset of lung cancer is their own fault.

The lung cancer stigma “affects society, and it horribly affects patients,” giving “them an added burden on top of the burden of their illness,” says oncologist Mark Kris, a medical, on the official website of New York City’s Memorial Sloan Kettering Cancer Center.

Sloan Kettering notes that about 85% of people diagnosed with lung cancer are current or former smokers. But the disease is so common that a large number of non-smokers are diagnosed annually. For instance, the American Cancer Society predicts that roughly 234,000 Americans will be diagnosed with lung cancer this year. If 15% are non-smokers, that comes to about 35,000 people.

In Taiwan, non-smokers may be at a much higher risk of developing lung cancer than in the United States. The ongoing eight-year study has found that non-smokers here are twice as likely to develop the disease than are heavy smokers in the United States and Europe.

Chen Yu-min, an oncologist at Taipei Veterans’ Memorial Hospital and one of the leaders of the study, notes that 52% of Taiwan’s lung cancer patients were never smokers, more than triple the rate in most other countries. Some 83% of them have adenocarcinoma. While this form of lung cancer is curable if caught early enough, it has a tendency to spread to the blood vessels, regional lymph nodes, and sometimes the brain in later stages. Lung cancer patients with brain metastases have a poor prognosis, with survival usually of less than one year.

Hereditary factors, which are not yet fully understood, may be one reason for the prevalence of lung carcinoma in non-smoking Taiwanese, Chen says. Environmental factors are also involved, he notes. One of those is exposure to cooking fumes without proper ventilation, as has been suggested by several studies done in Taiwan since the 1990s. Researchers found that Taiwanese often wait until cooking oil is sizzling to cook food. At such high temperatures, toxic fumes from the oil are released into the surrounding air. Of course, many Taiwanese do use proper ventilation when cooking, curbing their exposure to carcinogenic fumes.

A bigger concern for oncologists is air pollution. In 2013, the IARC classified outdoor air pollution as carcinogenic to humans. It found that air pollution caused 223,000 lung cancer deaths worldwide in 2010. In Taiwan, “air pollution may be a factor that contributes to the incidence of lung cancer,” says Merck’s Chueh.

Taiwan’s air quality was poor for decades, especially in the smoggy 1970s and 1980s. Since the government did not begin measuring PM2.5 (particulate matter with a diameter of less than 2.5 micrometers) until 2013, there is no data from Taiwan’s most polluted period to prove how bad the air was, notes Chen. But older Taiwanese remember the constant smog, he says.

People who resided close to industrial zones years ago possibly were exposed to large amounts of carcinogenic fumes. Now in their 50s, 60s, and 70s, a small percentage of them may be developing lung cancer.

To be sure, Taiwan’s air quality has improved markedly in recent years, but it still leaves much to be desired. The Tsai Ing-wen administration attributes much of the poor air quality in winter – when PM2.5 levels can reach an alarming 200 in central and southern Taiwan – to pollutants that blow across the Taiwan Strait from China.

Greater use of wind energy, which emits almost no pollutants, could reduce the amount of carcinogens in Taiwan’s air. Photo: Matthew Fulco

Some Taiwanese place the blame closer to home. In December, thousands marched in Taichung and Kaohsiung, urging an end to coal as an energy source. A December report in the English-language Taipei Times quoted Hsu Hsin-hsin, a member of the Taiwan Healthy Air Action Alliance, as saying the government is “trying to fool the public” by focusing on China’s contribution to Taiwan’s air pollution.

Inevitably, pressure is building on the government to modify its anti-nuclear power policies. In February, the Taiwan Power Co. (Taipower), the state-run electricity provider, said it would request permission from the Atomic Energy Council (AEC) to restart the No. 2 nuclear power plant’s second reactor, which has been offline since May 2016 after being shut for repairs.

Further, following requests by government agencies to reduce carbon admissions, Taipower slashed coal consumption at a Taichung plant by 24% and reduced coal use at a Kaohsiung plant as well, according to a February report by the Central News Agency.

Given the correlation between air pollution and lung cancer, the government should wait to phase out nuclear power until cleaner energy sources can fully pick up the slack, says Taipei Veterans General Hospital’s Chen. “We don’t want to be in a situation where we’re burning more coal.”

Preventive care

As lung cancer incidence rises in Taiwan, some medical professionals are urging preventive care. Lung screening with a CT scan is the only proven way to detect the disease when it is still curable. Yet Taiwan’s National Health Insurance (NHI) program covers screening costs only if patients meet certain criteria. They must be smokers or former smokers (having quit in the last 15 years) aged 55 to 77, who previously smoked the equivalent of a pack a day for 30 years.

These criteria mirror guidelines set by the United States’ Centers for Medicare and Medicaid Services (CMS). The American Cancer Society acknowledges that non-smokers can develop lung cancer, but says that insufficient evidence exists to justify screening them.

Out of pocket, lung screening in Taiwan costs about NT$6,000 (US$200), which is too high for most Taiwanese, says former NTUH vice president Wang. “Salaries are too low here. People don’t have that much spare cash to spend on preventive healthcare.”

With that in mind, Wang in 2015 established a small branch hospital of NTUH in Zhudong, a city in Hsinchu County. He raised NT$20 million (US$667,000) to set up the facility and equip it with state-of-art equipment, including CT machines, he says.

At the hospital, the cost of a CT scan is just NT$2,000. The volume of patients makes the business sustainable. Wang says that of those screened at the facility, 3.5% had a tumor larger than 1 centimeter and 5% had a nodule bigger than 0.6 centimeters.

Peter Cheng, a retired semiconductor engineer in his early 60s, is a lung cancer survivor who was screened at the NTUH Zhudong branch in 2016 at his daughter’s request. Cheng is a former smoker who had quit for eight years at the time of his screening. With no prior history of lung disease, he was shocked when the results of his screening showed a 1.5 cm tumor on his lung.

“I had no symptoms at all and felt like I was in perfectly good health,” he told Taiwan Business TOPICS. Since the cancer was a Stage 1 NSLC, his doctors recommended surgery. A successful surgical resection of the tumor was performed at NTUH in Taipei about a month after it was discovered.

To date, Cheng remains cancer-free. “I’m very lucky that I could do the examination for a reasonable price and that my cancer was operable,” he says.

Cheng does not know what caused his cancer, but he is adamant about the health risks posed by air pollution. “At this point, Taiwan’s air pollution is probably bad enough to cause lung cancer,” he says.

The type of cancer Cheng had accounts for 80-85% of all lung cancers. Another 10-15% are a more implacable form of the disease called small-cell lung cancer (SCLC). Almost all SCLC cases (more than 95%) are caused by smoking or exposure to second-hand smoke. “Small-cell lung cancer is biologically a more aggressive disease than non-small cell lung cancer,” says MSD’s Chueh. “It tends to metastasize when the primary lung tumor is small in size, and is more likely to relapse even after curative intent therapy.”

For that reason, SCLC is notoriously hard to treat. Surgery is rarely an option. Yet if a CT scan discovers the disease in a nascent stage before it causes any symptoms, it can be cured, says Chen of Taipei Veterans Memorial Hospital.

While lung screening has the potential to save lives, the Taiwan government has yet to recommend the examination for the general public because of the small health risk from radiation from the CT scan, even though it is a low dose.

In Wang’s view, the high incidence of lung cancer in Taiwanese non-smokers requires a different approach to screening than in the United States. “We hope we can eventually use the data we gather and persuade the government to lower the cost of preventive screening and encourage people to do it,” he says.  “Yes, you are exposed to a small amount of radiation when you get screened. But it could save your life.”