Evaluation of the role of circular RNA (circ-FAF1) as a diagnostic biomarker for breast cancer in a cohort of Egyptian breast cancer patients.

Background: The identification of circulating potential biomarkers may help earlier diagnosis of breast cancer, which is critical for effective treatment and better disease outcomes. We aimed to study the role of circ-FAF1 as a diagnostic biomarker in female breast cancer using peripheral blood samples of these patients, and to investigate the relation between circ-FAF1 and different clinicopathological features of the included patients.

Methods and results: This case-control study enrolled 60 female breast cancer patients and 60 age-matched healthy control subjects. For all study subjects, serum samples were collected for RNA extraction followed by reverse transcription and quantitative real time polymerase chain reaction for circ-FAF1 relative expression level. Serum circ-FAF1 was significantly downregulated in the studied patients compared to control subjects (p < 0.001). Low expression level of circ-FAF1 was significantly associated with presence of lymph node spread (p < 0.001), positive metastasis (p = 0.002), estrogen receptor negativity (p < 0.001), HER2 positivity (p < 0.001), and it was moderately correlated with higher Ki-67 index (r=-0.429, p = 0.001). However, circulating circ-FAF1 level had no statistically significant correlation with progesterone receptor status (p = 0.053), tumor histopathological type (p = 0.895) and histological grade (p = 0.369). Using ROC curve, serum circ-FAF1 had an AUC of 0.885, 81.67% diagnostic sensitivity and 76.67% diagnostic specificity.

Conclusion: Serum level of circ-FAF1 is a promising biomarker that can help in diagnosis of breast cancer. The low expression in breast cancer was correlated with lymph node spread, presence of metastasis, and with histopathological parameters suggestive of a worse outcome in these patients.