New Delhi, Dec 2 : While smoking tobacco is one of the major reasons behind lung cancer, a new study suggests genes may also be a risk factor. The study, published in journal The Lancet, showed evidence for a family history of lung cancer in individuals who do not smoke. The study included 12,011 people from Taiwan where lung cancers occur predominantly in never-smokers, and of whom nearly 60 per cent have stage IV disease at diagnosis. 'In individuals who do not smoke, our findings suggest that a family history of lung cancer among first-degree relatives significantly increases the risk of lung cancer as well as the rate of invasive lung cancer with increasing age,' said researchers including from the National Taiwan University in Taipei. The team aimed to assess the efficacy of low-dose CT (LDCT) screening among never-smokers, who had other risk factors for lung cancer. Between 2015 and 2019, they examined 12,011 people of which 6,009 had a family history of lung cancer. The prevalence of invasive lung cancer was higher among participants with a family history of lung cancer (161 of 6,009 participants) than in those without (96 [1·6 per cent] of 6,002 participants). In participants with a family history of lung cancer, the higher the number of first-degree relatives affected, the higher the risk of lung cancer, participants whose mother or sibling had lung cancer were also at an increased risk. In participants with a family history of lung cancer, the detection rate of invasive lung cancer increased significantly with age, whereas the detection rate of adenocarcinoma in situ remained stable. Adenocarcinomas are cancers that start in glandular tissues that make mucus or fluid, such as the lung, breast, prostate, or colon. In multivariable analysis, female sex, a family history of lung cancer, and age older than 60 years were associated with an increased risk of lung cancer and invasive lung cancer; passive smoke exposure, cumulative exposure to cooking, cooking without ventilation, and a previous history of chronic lung diseases were not associated with lung cancer, even after stratification by family history of lung cancer. 'Further research on risk factors for lung cancer in this population is needed, particularly for those without a family history of lung cancer,' the researchers said. /IANS