Association of preoperative and postoperative circulating tumour DNA (ctDNA) with PIK3CA gene mutation with risk of recurrence in patients with non-metastatic breast cancer.

BACKGROUND: Circulating tumour DNA (ctDNA), contains tumour-specific gene mutation in blood circulation and could aid in postoperative risk stratification of non-metastatic breast cancer. In this study, we investigated the feasibility of detecting PIK3CA gene mutations in ctDNA in the preoperative (preop) and postoperative period (postop), and its prognostic significance in patients with breast cancer. METHODS: A cohort of patients with breast cancer undergoing curative surgery with available blood samples preoperatively and postoperatively (Post op) at either Post op time period; week 1-2, week 3-4 or weeks 5-12 were enrolled. PIK3CA gene mutations at exons 9 and 20 were detected in ctDNA with High resolution melting (HRM) PCR and Allele specific fluorescence probe-based PCR. RESULTS: A total of 62 patients (age, median (IQR), 51.50 (45.0-65.0) years), with a median follow-up of 90 months (interquartile range (IQR),60-120 months) were enrolled. In total, 25 (40.3%) and 22 (35%) patients with breast cancer had detectable PIK3CA gene mutations in ctDNA in preoperative and postoperative period, respectively. PIK3CA gene mutations in ctDNA in postoperative period (hazard ratio (H.R: 18.05, p = 0.001) were a negative prognostic factor for recurrencefree survival (RFS) and overall survival (OS) (H.R: 11.9, p = 0.01) in patients with breast cancer. Subgroup analysis of ctDNA indicate that positive ctDNA in both preoperative/postoperative period and post op period only were found to have prognostic effect on RFS and OS (RFS; p < 0.0001, O·S; p = 0.0007). Moreover, ctDNA-based detection preceded clinical detection of recurrence in patients with an average lead time of 12 months (IQR:20-28.5 months) across all the breast cancer subtypes. CONCLUSION: We highlighted the prognostic ability of ctDNA in patients with breast cancer in perioperative period. However, future prospective studies are needed to assess the utility of ctDNA in clinical practice.

Assessment of cell-free DNA (cfDNA) concentrations in the perioperative period can predict risk of recurrence in patients with non-metastatic breast cancer.

BACKGROUND: Circulating cell-free DNA (cfDNA) is a potential non-invasive biomarker of disease status in patients with cancer, and provides important diagnostic and prognostic information in breast cancer. The goal of this study was to quantify cfDNA concentrations during the perioperative period and investigate its potential utility to detect recurrence outcomes in patients with breast cancer. METHODS: Sixty-two (n = 62) patients with non-metastatic breast cancer, undergoing curative-intent surgery were screened for inclusion. Blood samples were collected from these patients: pre-operatively (Preop) and post-operatively (PO) at either of the following PO time points; PO week 1-2, PO week 3-4 and PO weeks 5-12 following surgery. cfDNA was extracted and quantified using nanodrop spectrophotometer. RESULTS: In a cohort of 62 patients (age, median (IQR), 51.5(45.0-65.0) years), with a median follow-up of 90 months (interquartile range (IQR),60-120 months), significant association was observed between cfDNA concentrations and risk of recurrence in patients with breast cancer. The group of patients who had disease recurrence during follow-up had significantly higher cfDNA concentrations (cutoff:400 ng/ml) compared to the group of patients who remain disease-free (Preop and PO period: p < 0.0001). The median Recurrence Free Survival (RFS) between the Disease Recurrence (DR) and the Disease Free (DF) groups of patients with breast cancer were 12(20-28.5) months and 72.00 (96-120) months; p < 0.0001). Univariate and multivariate cox regression analysis indicated that postoperative cfDNA concentration (Hazard ratio:5.0, 95% Confidence Interval:1.19-21.28, p = 0.028) was an independent negative prognostic factor for RFS in patients with non-metastatic breast cancer. CONCLUSION: Our study demonstrated that high postoperative cfDNA is associated with increased risk of future recurrence in patients with non-metastatic breast cancer. Further, prospective studies are warranted to validate its clinical utility in breast cancer.

Association of Circulating Tumor DNA With Disease-Free Survival in Breast Cancer: A Systematic Review and Meta-analysis.

Importance: Fragmented DNA is continuously released into the circulation following apoptosis and necrosis of both cancerous and noncancerous cells; when it is released by cancer cells, it is specifically known as circulating tumor DNA (ctDNA). Previous studies have suggested that ctDNA can reflect tumor burden and guide potential therapeutic targets. Objective: To determine the association of ctDNA with breast cancer disease-free survival (DFS) and progression-free survival in early, locally advanced, and metastatic breast cancer. Data Sources: An electronic search was conducted using the Cochrane Library, ScienceDirect, PubMed, and Embase from July 30, 2019, to October 31, 2019; all languages were included. The following search terms were used: ctDNA OR circulating tumor DNA OR liquid biopsy AND breast cancer OR breast carcinoma OR breast tumor AND prognosis OR survival. All titles were screened, and the appropriate abstracts were reviewed. If any data were missing, the authors contacted the study authors for permission to access data and extrapolate hazard ratios (HRs). Study Selection: To be included in the analysis, the studies had to meet the following prespecified inclusion criteria: (1) a ctDNA blood sample was measured; (2) DFS, progression-free survival, or relapse-free survival was reported as an HR; and (3) the patient population only had breast cancer. Retrospective and prospective observational cohort studies were included. Data Extraction and Synthesis: Two authors (C.C. and C.F.) independently reviewed the literature. All data were recorded independently by both authors and were compared at the end of the reviewing process to limit selection bias. Duplicates were removed and any disparities were clarified. Data were pooled using a fixed-effects or random-effects model according to the study heterogeneity. This study adhered to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) and Meta-Analysis of Observational Studies in Epidemiology (MOOSE). Main Outcomes and Measures: The primary outcome was the association of ctDNA with DFS or relapse-free survival in breast cancer. Secondary outcomes focused on subgroup analysis in the setting of early breast cancer and metastatic breast cancer. Results: From a total of 263 publications found using the predefined search terms, data from 8 studies (3.0%) reporting on 739 patients in total were suitable for inclusion. Circulating tumor DNA gene variation detection (both before and after treatment) was statistically significantly associated with shorter DFS (HR, 4.44; 95% CI, 2.29-8.61; P < .001). Detection of ctDNA was statistically significantly associated with a reduction in DFS in both the early breast cancer subgroup (HR, 8.32; 95% CI, 3.01-22.99; P < .001) and the metastatic or locally advanced subgroup (HR, 1.91; 95% CI, 1.35-2.71; P < .001). Pretreatment and posttreatment plasma sample collection was analyzed in both early and metastatic groups. The posttreatment group encompassed both surgical and oncologic therapy. Pretreatment plasma detection of ctDNA was statistically significantly associated with reduced DFS (HR, 3.30; 95% CI, 1.98-5.52; P < .001). Posttreatment sampling of ctDNA failed to achieve statistical significance (HR, 8.17; 95% CI, 1.01-65.89; P = .05). Conclusions and Relevance: In this systematic review and meta-analysis, elevated plasma ctDNA was associated with a high risk of relapse. This finding suggests that plasma ctDNA may provide an excellent method to stratify risk and personalize patient follow-up.