The changing NSCLC subtypes: cancer associated with non-smokers in the lead

19 January 2017 (Last Updated January 19th, 2017 09:13)

Lung cancer is one of the most common types of cancers worldwide, with non-small cell lung cancer (NSCLC) making up about 85% of all lung cancer cases. Understanding trends in lung cancer patient characteristics will be important for both disease prevention and treatment advancements.

The changing NSCLC subtypes: cancer associated with non-smokers in the lead

Lung cancer is one of the most common types of cancers worldwide, with non-small cell lung cancer (NSCLC) making up about 85% of all lung cancer cases. Understanding trends in lung cancer patient characteristics will be important for both disease prevention and treatment advancements. GlobalData epidemiologists forecast that by 2025, adenocarcinomas will take up a greater proportion of NSCLC cases than ever before, likely due to the reduction of smoking rates globally and improved diagnosis.

NSCLC has three main histological subtypes: adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. Adenocarcinoma is often found in the outer areas of the lung and is associated with lung cancer in never-smokers. Squamous cell carcinoma is most frequently found in the central large bronchi and is strongly linked with smoking. Large cell carcinoma can occur in any area of the lungs and is the most aggressive. Several additional subtypes of NSCLC also exist, but occur at very low frequencies. The classification of lung cancer is important because treatment depends on the specific histology of the cancer cells.

Historically, squamous cell carcinoma was the most common type of lung cancer in the US, but its proportion declined along with the decrease in smoking rates. Currently, adenocarcinoma makes up the majority of NSCLC cases in the eight major markets (8MM: US, France, Germany, Italy, Spain, UK, Japan, and urban China), followed by squamous cell carcinoma. Based on historical trends, adenocarcinoma is likely to increase in proportion while large cell carcinoma is likely to decrease. The shifts in histological subtype trends were thought to be attributable to changes in cigarette composition and design. Other studies also attributed the shift in higher adenocarcinoma to improved cancer diagnostic techniques.

We analyzed historical trends in subtype distributions in the 8MM and estimated what the NSCLC patient population may look like in 2025. The figure below compares the forecast subtype distribution with historical subtype distribution. Adenocarcinoma is expected to increase, while the other subtypes are expected to decrease. Along with the shift in NSCLC subtypes, we expect NSCLC survival to improve because survival varies by histology subtype. Adenocarcinoma has the highest survival, followed by squamous cell carcinoma and then large cell carcinoma.

Details about the trend analysis and other discussions of NSCLC epidemiology in the 8MM can be found in the EpiCast Report: Non-Small Cell Lung Cancer (NSCLC) – Epidemiology Forecast to 2025.