Dear Editor,

I appreciate Dogra et al. (1) for their systematic review on the prognostic significance and molecular classification of triple-negative breast cancer (TNBC). It takes a lot of time and effort to collect and analyse this amount of data. The results provide valuable insight into different subtypes of TNBC along with their prognosis. However, I wish to bring your attention to some of the issues in the methodology and data extraction.

Systematic reviews and meta-analyses are generally not included in conducting systematic reviews as these are secondary data, unless it’s a “meta-meta-analysis” or “review of review”. Alternatively, if systematic reviews are included, then studies of the same period should be excluded from the search. Where the authors did mention that review articles were to be excluded, the inclusion criteria included systematic reviews and meta-analyses.

The Study selection process lacks clarity. The authors claim that 421 studies were finally included for meta-analyses after completing the selection process. However, as per Preferred Reporting Items for

Systematic Reviews and Meta-Analyses (PRISMA) flowsheet, 708 articles were removed out of 771 leaving only 63 articles. The study selection process does not cater for the specifically mentioned “studies included in quantitative synthesis (n = 58)” in the PRISMA flow diagram. The PRISMA flow diagram includes 50 studies from other sources but study selection procedure does not include them.

As per the PRISMA 2020 flow diagrams for systematic reviews, excluded studies are lateralized from the main flow of remaining studies to keep things clear. This is not the case in this study as excluded studies are presented in the same flow making it difficult to understand. The studies from other sources also need to be presented in a different stem which joins the main stem at the end. This again is not the case in this study (2).

A breakdown of included studies on the basis of the study types such as randomized controlled trials (RCTs), clinical trials, cohort studies, case-control studies, and systematic reviews/meta-analyses is not mentioned. This also entails that the number of RCTs undergoing RoB and observational studies undergoing NOS is not made part of this study which is considered an essential in systematic reviews/ meta-analyses.

This review however provides useful information about this complex heterogenous disease and its implications for therapeutic strategies. Understanding molecular diversity is crucial in opting the right treatment modality in TNBC leading to better patient outcomes.

I really liked the segment of current gaps and future directions where authors admit a lack of consensus on molecular classification criteria leading to challenges in development of standardized clinical guidelines for each molecular subtype. This to date remains a controversial area.

The sole purpose of this input is to stimulate further discussion for clarity and improvement in future systematic reviews.