Quantitative analysis of plasma DNA in anal cancer patients

Introduction
The availability and non-invasiveness of circulating cell-free DNA (cfDNA) opens up new possibilities for real-time serial testing. The relationship between cfDNA concentration, clinical factors and suitability for monitoring was analyzed in patients with newly diagnosed anal squamous cell carcinoma (ASCC).

Material and methods
Blood samples were collected at several points during and after treatment. Patients were homogeneously treated with chemoradiotherapy.

Results
The concentration of cfDNA strongly correlated with the tumor volume (r = 0.9, p = 0.00006) and number of neutrophils (r = 0.706, p = 0.0069). Monitoring of cfDNA levels during treatment showed an increase after initiation of therapy, a peak at the end of treatment with significantly higher values for advanced than in T1/T2 tumors, and a decrease (T3/T4) during follow-up. However, neither the concentration of cfDNA before treatment nor its changes correlated with the response to chemoradiotherapy. There was no association between baseline cfDNA levels and T, N, age and gender.

Conclusions
Substantial changes in plasma cfDNA content can be observed after chemoradiotherapy for ASCC. However, the small number of cases studied makes it difficult to assess the usefulness of the cfDNA test.