Background: Breast cancer is the most common type of tumor in women and becoming a major threat that results over 1.5 million morbidities and 570,000 deaths globally in each year. So determining hematological profile is important for the early diagnosis and treatment of women with breast cancer.

Objective: To determine the pooled hematological profile changes in women with breast cancer.

Evidence Acquisition: The current study followed the Preferred Reporting Items for systematic reviews and meta-analyses checklist. Searches for relevant literature were conducted on scientific databases such as the biomedical journal database, the scientific information database, the global medical article library, Scopus, PubMed, Science Direct, Springer, Web of Science, the Wiley online library, and Google Scholar. All population-based studies up to September 2023 were included based on inclusion criteria. Using a random effects model, the data were analyzed through STATA software (ver.11.1).

Results: Overall data from nine included studies in this meta-analysis by random effect model showed that the pooled mean of WBC, RBC, and Platelet in women with breast cancer was 4.24 x 10 9 (95% CI: 3.88 x 10 9 , 4.6 x 10 9 ), 4.80 x 10 12 (4.33 x 10 12, 5.24 x 10 12 ), and 223.18 x 10 9 (95% CI: 187.8 x 10 9 , 259.18 x 10 9) respectively in random effect model. The pooled mean differences of WBC, PLT, Hgb, lymphocyte, MPV, and RDW were (-0.72 95% CI: -0.77, -0.67), (-6.68 95% CI: -7.90, -5.47), (-0.36 95% CI: -0.41,-0.32), (-0.52 95% CI: - 0.68, -0.36), (1.67 95% CI: 1.23, 2.11) and (0.40 95% CI: 0.16, 0.64) respectively.

Conclusion and recommendation: A decreased complete blood count with increased RDW and MPV can be used as a marker for the presence and prognosis of breast cancer. So early determination of hematological profiles especially MPV, and RDW is important for screening of breast cancer.