Worldwide Lung Cancer Incidence and Distribution by Subtype

Why Is Lung Cancer a Critical Problem?

Lung cancer remains the most common cancer worldwide. However, variations in lung cancer incidence by histological subtype and regional differences have not been fully understood. Published on February 3, 2025, in THE LANCET Respiratory Medicine this study aimed to examine the distribution of lung cancer subtypes in different regions of the world in 2022, determine the effects of environmental factors on these cancer types, and assess historical trends between 1988-2017.

Study Design

This study analyzed population-based data using information from the Global Cancer Observatory (GLOBOCAN) 2022, Cancer Incidence in Five Continents (VII-XII), and the African Cancer Registry Network.

Across 179 countries worldwide, the four main lung cancer subtypes (adenocarcinoma, squamous cell carcinoma [SCC], small cell carcinoma, and large cell carcinoma) were examined, and age-standardized incidence rates were calculated.

The age-standardized incidence rate is a statistical measure that adjusts cancer rates in different age groups to a standard age distribution, allowing direct comparisons between populations. This enables fair comparisons between regions with different age distributions.

The researchers also estimated how many adenocarcinoma cases were attributable to ambient particulate matter (PM), or air pollution, and examined changes in these trends over time.

Findings

Worldwide in 2022, an estimated total of 2.48 million new lung cancer cases occurred:

• Men: 1.57 million new cases
  • Adenocarcinoma: 717211 cases (45.6%)
  • SCC: 461171 cases (29.4%)
  • Small cell carcinoma: 180063 cases (11.5%)
  • Large cell carcinoma: 101861 cases (6.5%)
• Women: 908630 new cases
  • Adenocarcinoma: 541971 cases (59.7%)
  • SCC: 155598 cases (17.1%)
  • Small cell carcinoma: 87902 cases (9.7%)
  • Large cell carcinoma: 59271 cases (6.5%)

The following regional differences stood out:

Men:

• Adenocarcinoma was most common in East Asia (27.12 cases per 100000 people). This rate means that 27 people per 100000 are diagnosed with adenocarcinoma annually.
• SCC and small cell carcinoma were most common in Eastern Europe (SCC: 21.70 cases per 100000 people; small cell carcinoma: 9.85 cases per 100000 people).
• Large cell carcinoma had its highest rate in North Africa (4.33 cases per 100000 people).

Women:

1. Adenocarcinoma was most common in East Asia (19.04 cases per 100000 people).
2. SCC and small cell carcinoma had their highest rates in North America (SCC: 5.28 cases per 100000 people; small cell carcinoma: 4.28 cases per 100000 people).
3. Large cell carcinoma was most common in Northern Europe (2.87 cases per 100000 people).

The proportions of adenocarcinoma cases attributable to air pollution were also noteworthy:

Air pollution accounted for 114486 cases in men and 80378 cases in women.

In men, adenocarcinoma attributable to PM pollution occurred at an annual rate of 2.35 cases per 100000 people.

In women, adenocarcinoma attributable to PM pollution occurred at a rate of 1.46 cases per 100000 people.

Here, PM (particulate matter)refers to fine dust and pollutant particles suspended in the air that can enter the lungs through inhalation and cause serious health problems such as cancer.

Conclusion and Commentary

This study shows that lung cancer varies by subtype across regions and that adenocarcinoma incidence, in particular, is associated with environmental factors such as air pollution. Distinct trends in certain subtypes were identified, especially in industrialized regions such as Asia, Europe, and North America.

In the context of the global cancer burden lung cancer remains the most common cancer worldwide, with an estimated 2.5 million people developing the disease in 2022. The age-standardized annual rate of new cases was calculated as 23.6 cases per 100000 people.

Over the past few decades, lung cancer incidence has generally declined in men, whereas it continues to increase in women . Changes in cigarette manufacturing and smoking habits over time have influenced the differing incidence rates of lung cancer subtypes. There is also growing evidence that air pollution, particularly particulate matter (PM) pollution, increases the risk of adenocarcinoma.

Turkey, where 27.3% of the adult population smokes, has the highest smoking rate among European countries. This increases the risk of lung cancer becoming an even more serious public health problem in Turkey.

Changes in smoking habits and exposure to air pollution are major determinants of current differences in lung cancer incidence by subtype. Trends that differ by sex offer important insights for cancer prevention specialists and policymakers in developing smoking and air pollution control strategies tailored to high-risk populations.