ABSTRACT
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.
Subject(s)
Breast Neoplasms/genetics , Breast Neoplasms/pathology , Circulating Tumor DNA/genetics , Aftercare , Breast Neoplasms/blood , Breast Neoplasms/mortality , Circulating Tumor DNA/blood , Disease-Free Survival , Female , Humans , Neoplasm Metastasis/genetics , Neoplasm Metastasis/pathology , Neoplasm Recurrence, Local/genetics , Neoplasm Staging , Observational Studies as Topic , Precision Medicine/methods , Prognosis , Progression-Free Survival , Prospective Studies , Retrospective StudiesABSTRACT
The systemic inflammatory response plays a role in tumor progression and development. The neutrophil to lymphocyte ratio (NLR) is a biochemical marker of systemic inflammation and is increasingly gaining appreciation for its prognostic role in predicting breast cancer outcomes. Previous research has demonstrated that patients who achieve a complete pathologic response (pCR) to neoadjuvant breast cancer treatment have a more favorable disease-free survival. This study aimed to assess whether the NLR can predict pCR to neoadjuvant therapy in breast cancer. A meta-analysis of 8 relevant studies was performed. The primary endpoint included pCR. Secondary endpoint included 5-year disease-free survival. Eight studies were included, reporting on 1586 patients. A total of 363 (22.88%) patients achieved pCR post neoadjuvant therapy. A lower NLR was associated with a greater rate of pCR (odds ratio, 1.83; 95% confidence interval, 1.15-2.91; P = .0003). Only 4 studies produced data on disease-free survival. A lower NLR was associated with a higher 5-year disease-free survival; however, this did not achieve statistical significance (hazard ratio, 1.38; 95% confidence interval, 0.82-2.31; P = .02). Sub-group analysis of sample size, NLR value, and geographic location proved statistically significant in determining an association between NLR and pCR. This meta-analysis found NLR to be a predictor for pCR in patients with breast cancer. All of the studies reviewed were retrospective cohort studies. Adequately sized, prospective clinical trials are needed to understand if NLR could become an important prognostic indicator of pCR.
