Interval lung cancers not detected on screening chest X-rays: How are they different?

Area of Science:

• Oncology
• Radiology
• Public Health

Background:

• The Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO) offers a unique dataset to analyze interval lung cancers.
• Interval lung cancers are those not detected by screening chest X-rays (CXRs).

Purpose of the Study:

• To compare the characteristics of interval lung cancers with those detected during screening.
• To identify demographic, clinical, and pathological differences between true interval and screen-detected lung cancers.

Main Methods:

• Analysis of data from the PLCO trial, including participants randomized to the screening arm.
• Chest X-rays (CXRs) were performed at baseline and annually. Screen-detected cancers were identified via positive CXRs. Interval cancers were defined as lung cancers diagnosed within 12 months of a negative CXR.
• Potential interval cancers were re-reviewed to classify them as missed during initial interpretation or true interval cancers.

Main Results:

• Of 127 re-reviewed potential interval cancers, 45 (35.4%) were likely missed at screening, and 82 (64.6%) were true interval cancers.
• True interval lung cancers were more prevalent in males, individuals with less than 12 years of education, and smokers.
• Compared to screen-detected cancers, true interval cancers were more frequently small cell carcinoma (28.1% vs. 7.4%), advanced stage IV (30.5% vs. 16.6%), and less often adenocarcinoma (25.6% vs. 56.2%).

Conclusions:

• True interval lung cancers exhibit distinct demographic, staging, cell type, and location characteristics compared to screen-detected lung cancers.
• These findings highlight the limitations of CXR screening in detecting all lung cancers and underscore the importance of understanding interval cancers for improved lung cancer management.