# Potential for trans-pulmonary tumor markers in the early diagnosis of lung cancer: a case report

## TL;DR

This case report explores using trans-pulmonary tumor markers to improve early lung cancer diagnosis by measuring marker gradients near lung tumors.

## Contribution

The study introduces trans-pulmonary sampling as a novel method to detect tumor markers closer to lung cancer sites.

## Key findings

- Tumor marker levels increased across the pulmonary circulation, exceeding assay variability.
- Pulmonary artery wedge concentrations of CYFRA and HE4 were over 10% higher than peripheral venous levels.
- Peripheral arterial samples showed up to 8% higher marker levels than peripheral venous samples.

## Abstract

Measurement of tumor markers from peripheral venous blood is an emerging tool to assist in the early diagnosis of lung cancer. Samples from the pulmonary artery and pulmonary artery wedge position (trans-pulmonary samples) are accessible via right-heart catheterization and, by virtue of their proximity to lung tumors, may increase diagnostic yield.

We report a case of a 64 year-old woman from whom trans-pulmonary samples were obtained and who was diagnosed 16 months later with recurrent metastatic small cell lung cancer. Carcinoembryonic antigen, cytokeratin fragment 21 − 1 (CYFRA), and human epididymis protein 4 (HE4) levels demonstrated increasing concentrations across the pulmonary circulation. These gradients exceeded the assays’ coefficient of variation by several-fold. For CYFRA and HE4, pulmonary artery wedge concentrations exceeded peripheral venous levels by more than 10% and peripheral arterial levels were up to 8% higher than peripheral venous levels.

Evaluating the feasibility and utility of trans-pulmonary tumor markers for lung cancer diagnosis in a larger cohort should be considered. The addition of a peripheral arterial sample to standard peripheral venous samples may be a more practical alternative.