Evaluation of Risk Factors for Lung Cancer Among Never Smokers and Their Association With Common Driver Mutations

INTRODUCTION

The majority of lung cancers are caused by tobacco use, which is linked to lung tumors of all major histological types. A considerable fraction of lung cancer cases, the vast majority of which are adenocarcinomas, occur in "never smokers," who are characterized as having smoked fewer than 100 cigarettes in their lives. The primary objective was to assess risk factors for lung cancer in non-smokers. In contrast, secondary objectives included evaluating histological subtype, staging, and performance status and exploring associations between risk factors and common driver mutations.

MATERIAL AND METHODS

The study was a single-center, observational, case-control study done at All India Institute of Medical Science, Bhubaneswar, India that focused on non-smokers with lung cancer. It included 145 cases and 297 controls, with statistical analyses such as chi-square tests and logistic regression used to assess associations between risk factors and lung cancer, considering factors such as socioeconomic status, body mass index (BMI), occupation, outdoor and indoor air pollution, personal habits, and medical history.

RESULTS

The study, comprising 145 lung cancer cases in non-smokers and 297 controls, found that 92.4% (134/145) of cases had adenocarcinoma, 6.9% (10/145) had squamous cell carcinoma, and 0.7% (1/145) had small cell carcinoma. Significant associations were observed for high-risk occupations, indoor biomass use without proper ventilation, low BMI, and family history of lung cancer. Specific pre-existing lung conditions like old pulmonary tuberculosis and asthma were linked to increased and decreased odds of developing lung cancer, respectively. Environmental factors, living near heavy industry, and dietary habits showed significant associations. A significant association was not found between the driver mutations and the risk factors studied.

CONCLUSION

This single-center study sheds light on significant risk factors influencing lung cancer development among non-smokers. The predominant occurrence of adenocarcinoma and associations with high-risk occupations, indoor biomass exposure, low BMI, and family history emphasize the multifaceted nature of non-smoking-related lung cancer. The findings underscore the importance of comprehensive risk assessment and targeted preventive strategies in this population.

A lung cyst harbouring a congenital pulmonary varix

A non-smoker man in his second decade presented to a medical centre with intermittent haemoptysis over 2 years. The haemoptysis was infrequent initially to be ignored, but later, the episodes increased in amount and frequency. Routine blood tests including coagulation profile showed normal results. The chest radiography and echocardiography were normal. The contrast-enhanced CT scan of the chest showed a cystic lesion with intracystic abnormality and surrounding ground-glass opacity in the left upper lobe. The CT pulmonary angiography and invasive pulmonary angiography showed the abnormality to be a dilated pulmonary vessel draining into the left atrium, thereby confirming the diagnosis of congenital pulmonary varix contained within a lung cyst. The patient underwent a successful lobectomy following which he experienced no further haemoptysis.

A 37-Year-Old Man With Dyspnea, Bilateral Lung Consolidation, and a Tracheal Mass

CASE PRESENTATION

A 37-year-old man presented to the ED with symptoms of productive cough, self-reported fever, and shortness of breath for the past 15 days. He was placed on noninvasive mechanical ventilation for respiratory distress. IV piperacillin-tazobactam and inhaled bronchodilators were promptly administered, and he was subsequently transferred to the respiratory ICU for further care. He had no history of bowel and bladder disturbance, altered sensorium, swelling of feet, or abdominal distention. He never used tobacco and denied a history of TB. Medical history was notable for recurrent hospitalizations and administration of multiple courses of antibiotics in the past for similar complaints. He often used inhaled bronchodilators/corticosteroids when clinically stable to relieve symptoms.