SEOUL, May 30 (Yonhap) -- The World No Tobacco Day is just around the corner, but South Korea's high smoking rate continues to make both smokers and nonsmokers more vulnerable to lung cancer, a study showed Thursday.
In a study published in the Journal of Korean Medical Science last month, the team of researchers led by a Jeju National University professor showed that smokers were four times more likely to develop lung cancer than nonsmokers.
The research is the nation's longest longitudinal study as 14,500 South Korean male subjects were observed over a 16-year period ending in 2008.
Quitting smoking would reduce lung cancer risks by more than 50 percent, the study led by Professor Bae Jong-myon showed, since 55.8 percent of lung cancer cases in South Korea were attributed to smoking.
The relative risk for lung cancer associated with tobacco, however, remained unchanged compared with previous shorter studies. A 10-year cohort study by the same researchers in 2007 showed that smokers were 4.2 times more likely to develop lung cancer than nonsmokers, little change from the 2013 study.
Researchers said the prevalence of secondhand smoke in South Korea may explain why the relative risks have stayed the same between the two studies.
"The fact that people who have been smoking for different periods of time have the same chances of getting lung cancer means that secondhand smoke is becoming a serious problem in South Korea," Bae said.
South Korea's smoking rate was the second highest among 35 Organization for Economic Cooperation and Development countries in 2009. Though the rate dropped from 28.8 percent in 2005 to 27 percent in 2011, much work remains to prevent the long-term consequences of smoking.
A separate study released on Thursday found that teenage smokers were more likely to become heavy smokers than those who began later.
In a report submitted to the Korea Institute for Health and Social Affairs, health ministry official Cho Kyeong-suk said over 25 percent of the 1,241 South Korean smokers studied were identified as hardcore smokers, dragging 15 cigarettes a day and unwilling to quit in the next six months.
"The earlier people begin smoking, the more likely they are to become hardcore smokers," Cho said in the report. "This calls for solid preventative measures against teenage smoking and an anti-tobacco program specifically catered toward hardcore smokers."
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