The role of ct-DNA in breast cancer surveillance assessing treatment response and recurrence: A community center experience.

Abstract

e13021 Background: Breast cancer is a heterogeneous disease and primarily classified on immunohistochemistry. Currently treatment is based on biopsy but studies have showed changes in subtype and acquired resistance in the original subtype due to cancer therapies. While biopsy is gold standard, recently liquid biopsy from serum containing circulating tumor DNA (ct-DNA) has emerged as a noninvasive technique of tumor surveillance. Methods: This is a retrospective study approved by the IRB at Monmouth Medical Center. Objectives were to identify use of ct-DNA level and highlight the trends over course of treatment. Subjects were identified by reviewing patient’s charts and included on criteria of age > 18 years and in whom ct-DNA level was followed up. 27 patients were identified and results were obtained by categorizing the patients and calculating the proportions. Results: A total of 27 patients were included. The mean age at diagnosis of cancer was 56.29 years (95% CI 51.19-61.39). Among 27 patients, 11 had left sided and 16 had right sided tumor. The pathology identified was Invasive ductal in 18, adenocarcinoma in 2, lobular in 4, poorly differentiated in 2 and mesenchymal in 1 of the patients. Hormonal subtypes identified were triple negative in 11, ER/PR+ve/Her 2-ve in 8, triple positive in 2, ER/PR-ve/Her 2+ve in 1 and ER+ve in 5 of the patients. Among 27, 8 of the patients had stage I, 15 had stage II, 3 had stage III and 1 had stage IV disease. During the course of treatment, 7 of patients had left, 10 had right and 7 had bilateral mastectomy due to BRCA mutation identified on genetic testing. 3 of the patients did not undergo surgery. ct-DNA levels were elevated 8.05 and 1.31 MTM/ml in 2 patients and subsequently became undetectable and decrease in tumor size was noticed from 6.1 cm to 1.1 cm and 1.8 cm to 9mm. ct-DNA levels remained undetectable the rest of 25 patients and patient’s remained gross tumor free on interval MRI imaging of the breasts. Conclusions: The ct-DNA levels have a great utility in establishing the correlation of treatment effect on tumor volume. All this information is vital for clinical decision making and appropriate management. Therefore, the application of liquid biopsy and ct-DNA analysis in breast cancer opens a window of opportunity that encompasses all possible disease situations: from early diagnosis, through the detection of minimal residual disease, the early detection of relapse, and the monitoring and treatment planning for advanced disease. A limitation of study was low sample size. [Table: see text]