Measuring Radiation Toxicity Using Circulating Cell-Free DNA in Prostate Cancer Patients

Area of Science:

• Oncology
• Radiation Oncology
• Biomarkers

Background:

• Circulating cell-free DNA (cfDNA) rises after radiation therapy (RT) due to tissue damage.
• cfDNA can be measured within hours of RT initiation.
• This study investigated the correlation between cfDNA levels and toxicity in prostate cancer patients undergoing RT.

Purpose of the Study:

• To examine the relationship between cfDNA levels during the first week of RT and early/late gastrointestinal (GI) and genitourinary (GU) toxicity.
• To determine if cfDNA can serve as a predictive biomarker for RT-induced toxicities.

Main Methods:

• Prospective study of 54 patients receiving RT for nonmetastatic prostate cancer.
• Blood samples collected pre-RT and daily during the first week of RT.
• Toxicity assessments (GI and GU) performed at baseline, weekly during RT, and at 6 and 12 months post-RT.

Main Results:

• No grade 3 or higher toxicities were observed.
• Acute and late grade 2 GI toxicity showed significant correlation with pre-RT cfDNA and cfDNA levels during RT.
• Acute and late GU toxicity did not correlate significantly with cfDNA levels.

Conclusions:

• cfDNA levels show potential for predicting GI toxicity in patients undergoing prostate cancer RT.
• cfDNA may offer a biological estimate to complement traditional dose-volume histogram assessments.
• Further multi-institutional studies are underway to validate these findings.