Lung cancer remains the most common type of cancer by far in men and women, and it kills around 1.6 million people every year. The disease is not only impacting long-time smokers. New work reported in eBioMedicine looked at the biggest risk factors for the disease by assessing questionnaires and health records from 65,000 Norwegians. Three years of research showed that most lung cancer patients - 94 percent - were either ex-smokers smokers. For the other six percent who didn’t smoke, no obvious risk factor emerged.
People who smoked under 20 cigarettes a day for fewer than 20 years made up 36 percent of cases. Computer tomography (CT) screening has previously been recommended for smokers who’ve had 20 or more cigarettes for 30 years. That is a costly and dangerous screening method, however. The repeated doses of radiation that come with it can cause harm. Scientists wanted to find another way to precisely identify those who are at risk.
An international team of researchers from a variety of fields including oncology, statistics, and bioinformatics elucidated seven risk factors. They were able to engineer a risk calculator that determines an individual’s risk of lung cancer development within six and sixteen years. They named their tool the HUNT Lung Cancer Risk Model.
We already know some of their risk factors: cigarette intake - both the number of cigarettes smoked every day and number of years 20 cigarettes were smoked daily, an individual’s age, and how long it has been since they stopped smoking. Another known factor was confirmed to be body mass index (BMI); people with a higher BMI have a higher risk.
The team also added two new risk factors: a periodic cough, and the amount of time a person is also exposed to smoke indoors, where unsurprisingly, an increase in exposure increases risk.
After checking their findings against Norwegian health study participants, the group could predict the people who would get lung cancer with about 88 percent accuracy.
"The method can reduce the number of people exposed to radiation from unnecessary CT scans, and maximize identification of persons with true risk," said Oluf Dimitri Røe, a senior oncologist at the Department of Oncology, Levanger Hospital. "It is also the first model that can accurately predict lung cancer in light smokers, younger people, and people who quit smoking many years before."
According to the World Health Organization (WHO), tobacco use is the primary risk factor for cancer, likely causing about 22 percent of cancer worldwide. While lung cancer cases, in general, are declining, that is not true for every group. Detection is becoming increasingly important for young women, for whom lung cancer is on the rise; smoking does not count for that increase. Learn more about it from the video.
Sources: AAAS/Eurekalert! Via Norwegian University of Science and Technology, WHO, WebMD, eBioMedicine