Preventive Medicine: Lung Cancer

Image:a lit cigarette in an ashtray by Tomasz Sienicki. License: CC BY-SA 3.0

Introduction

Lung cancer is considered the most common cancer all over the world, where tobacco smoking is a recognized major modifiable risk factor leading to the disease. Cessation of tobacco smoking reduces the incidence and mortality by about 90%.

Epidemiology

Considering the gender-based statistics, breast cancer in women and prostate cancer in men are more common. Almost 14% of all the new cases are of lung cancer. For the year 2017, the American Cancer Society has given the following estimate for lung cancer in US populations

• About 116,990 new cases of lung cancer in men and 105,510 new cases in women.
• About 84,590 deaths from lung cancer in men and 71,280 in women.

Image: “Lung cancer in the left. bronchus as seen with a bronchoscope” by JHeuser. License: CC BY 2.5

Lung cancer is the leading cause of death in America. More people die of lung cancer each year than of prostate, breast, and colon cancers combined. The individuals diagnosed with lung cancer are usually ≥ 65 years. Only about 2 percent of the diagnosed cases are younger than 45 years.

The chances of developing a lung cancer for smokers and non-smokers during lifetime are as follows:

• 1 in 14 (for men)
• 1 in 17 (for women)

Smokers, however, have a greater risk as compared to non-smokers.

Screening

Lung cancers are usually at an advanced stage by the time they are diagnosed. Therefore, they are difficult to treat. The screening tests have, however, made it easy to diagnose the case early in the high-risk patients. Early diagnosis can improve the mortality rate.

Low-dose CT (LDCT) scan of the chest is used for screening of the lung cancer. LDCT uses a lower amount of radiations, and in contrast to standard CT scan, it does not require the intravenous contrast dye.

Screening criteria

Who Should Be Screened?

According to the U.S. Preventive Services Task Force recommendations, following people should undergo yearly lung cancer screening with LDCT:

• Individuals with a history of heavy smoking
• Individuals who are smokers or have quit smoking within the past 15 years
• 55 and 80 years old individuals
• 55 to 80 years old individuals with ≥ 30 pack-year smoking history and smoking cessation within less than past 15 years

Heavy smoking is a smoking history of ≥ 30 pack years.

Pack year: Smoking one pack of cigarettes each day for one year is equal to 1 pack year.

When to stop screening

The U.S. Preventive Services Task Force recommends that following groups of people should no longer receive yearly lung cancer screening with LDCT:

• People ≥ 81 years of age.
• A person who has not smoked for the past 15 years.
• An individual who develops a certain health condition that limits the life expectancy or the ability to undergo surgery in the case if lung cancer is diagnosed.