Commonest type of lung carcinoma in non smokers:

# Commonest type of lung carcinoma in non smokers:

A. Squamous cell carcinoma

B. Adenocarcinoma

C. Alveolar cell carcinoma

D. Small cell carcinoma

The correct answer is B. Adenocarcinoma. 

Types of Lung Carcinoma:

There are two main types of lung cancer: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). NSCLC is the most common type, accounting for about 80% of all lung cancers. Here's a breakdown of the options you provided:

Squamous cell carcinoma: This is a type of NSCLC that typically starts in the flat cells lining the airways of the lungs. Smoking is a major risk factor for squamous cell carcinoma.

Adenocarcinoma: This is also a type of NSCLC, and it's the most common type of lung cancer diagnosed in both smokers and non-smokers. It starts in the gland cells that make mucus in the lungs.

Alveolar cell carcinoma: This is a rare type of lung cancer that starts in the air sacs of the lungs. It's more common in smokers than non-smokers.

Small cell carcinoma: This is an aggressive type of lung cancer that can spread quickly. It's less common than NSCLC and is also more likely to occur in smokers.

Why Adenocarcinoma in Non-Smokers:

While smoking is the leading cause of lung cancer,  adenocarcinoma can develop in people who have never smoked. Here's why it's the most common type in non-smokers:

Risk Factors: Non-smoking related risk factors for adenocarcinoma include exposure to radon gas, secondhand smoke, air pollution, and a family history of lung cancer.

Cell Type: Adenocarcinoma originates in the gland cells lining the lungs, which are less affected by smoking compared to the cells targeted by squamous cell carcinoma.

Mutations:  Non-smokers with lung cancer are more likely to have specific gene mutations, particularly in the EGFR gene, which can drive the development of adenocarcinoma.