Adenocarcinoma Now the Most Common Type of Lung Cancer Worldwide

Adenocarcinoma has become the most common subtype of lung cancer worldwide, according to research published in The Lancet Oncology.

The study suggested that, in 2020, adenocarcinoma was the most frequently diagnosed subtype of lung cancer for women across all world regions. For men, adenocarcinoma was the most frequently diagnosed subtype in most regions studied.

Researchers calculated the incidence of lung cancer overall, by subtype, and by sex in 2020. Data were included for 185 countries and territories across 14 regions of the world.

There were an estimated 2,206,771 new cases of lung cancer worldwide in 2020, including 1,435,943 new cases in men and 770,828 new cases in women.

Globally, adenocarcinoma made up 57% of lung cancers in women (n=440,510) and 39% of lung cancers in men (n=560,108). Squamous cell carcinoma (SCC) made up 25% of lung cancers in men (n=351,807) and 12% in women (n=91,070).

Small cell lung cancer (SCLC) made up 11% of lung cancers in men (n=163,862) and 9% in women (n=68,224). Large cell lung cancer (LCLC) made up 8% of lung cancers in men (n=115,322) and 6% in women (n=49,246).

The global age-standardized rates of each subtype, per 100,000-person years, were:

• Adenocarcinoma — 12.4 in men and 8.3 in women
• SCC — 7.7 in men and 1.6 in women
• SCLC — 3.6 in men and 1.3 in women
• LCLC — 2.6 in men and 0.9 in women.

In the United States, adenocarcinoma cases made up 45% of all lung cancers among men (n=43,784) and 54% of all lung cancers among women (n=50,354). SCC made up of 34% of lung cancers in men (n=32,741) and 23% in women (n=21,544). SCLC made up 16% of lung cancers in men (n=15,527) and 18% in women (n=17,070). LCLC made up 5% of lung cancers in men (n=4676) and 4% in women (n=3916).

The researchers postulated that the changing patterns of lung cancer incidence by subtype are related to several factors, including changes in smoking prevalence and exposure to environmental carcinogens.

The researchers suggested that a decrease in smoking prevalence may have had a larger impact on the incidence of SCC, SCLC, and LCLC because quitting smoking reduces the risk of these subtypes more rapidly than adenocarcinoma.

In addition, studies have suggested that the high burden of adenocarcinoma in countries with high and very high Human Development Index values, such as the United States, could be related to living in highly polluted areas.

“Understanding the epidemiological profile of lung cancer incidence according to histological subtype can help health specialists gain insights on how to tailor cancer control policies in countries and world regions,” the researchers wrote. “Our findings provide important evidence for policy makers seeking to plan appropriate tobacco and other control strategies and optimize the allocation of resources accordingly.”

Reference

Zhang Y, Vaccarella S, Morgan E, et al. Global variations in lung cancer incidence by histological subtype in 2020: A population-based study. Lancet Oncol. Published online October 11, 2023. doi:10.1016/ S1470-2045(23)00444-8

This article originally appeared on Cancer Therapy Advisor