# A Case of Esophageal Cancer With Markedly Elevated Soluble Interleukin-2 Receptor: A Potential of Soluble Interleukin-2 Receptor as a Biomarker

## TL;DR

This case report shows that high levels of sIL-2R may be a useful biomarker for advanced esophageal cancer, even though it is typically used for blood cancers.

## Contribution

The study demonstrates that sIL-2R can be expressed in solid tumors like esophageal cancer, suggesting its potential as a new biomarker.

## Key findings

- The patient had extremely high sIL-2R levels despite normal levels of other tumor markers.
- Poorly differentiated cancer cells in the tumor expressed sIL-2R, but lymphocytes did not.
- sIL-2R may be a useful biomarker for staging and monitoring treatment in solid tumors.

## Abstract

We report an autopsy case of advanced esophageal cancer with multiple metastases that presented with a markedly high level of sIL-2R. An 83-year-old man was admitted to our hospital with a 1-week history of epigastric distress, appetite loss, and fatigue. Imaging examinations revealed a large liver tumor. Although the tumor markers for gastrointestinal and liver cancers were within normal limits, the sIL-2R level was extremely high (10,384 U/mL). The patient died immediately after admission due to the rapid course of the disease. An autopsy showed advanced esophageal cancer with multiple metastases, including the liver, lungs, and multiple lymph nodes. In histological examinations, esophageal cancer was a mixture of well- and poorly differentiated squamous cell carcinoma, in which poorly differentiated cancer cells expressed sIL-2R on immunohistochemical staining. However, we failed to detect positive staining for sIL-2R in the lymphocytes. Our findings revealed that solid tumors could express sIL-2R. Although sIL-2R is a tumor marker used for hematological malignancies, such as malignant lymphoma, this case report highlights the value of the measurement of sIL-2R levels in advanced solid tumors, including esophageal cancer. We concluded that sIL-2R has potential as a biomarker in advanced solid tumors for cancer staging and treatment response.