Document Type : Protocol
Authors
1
Mother and Newborn Health Research Center, Comprehensive Research Institute for Maternal and Child Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
2
Monoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
Abstract
Postpartum breast cancer (PPBC) is associated with poorer survival, higher metastatic rates, and distinct tumor biology versus breast cancer in nulliparous women or those with a longer delivery interval. Lactation, weaning, and postpartum mammary involution may create a pro-metastatic microenvironment, but evidence linking these exposures to prognosis and tumor-immune-stromal features has not been synthesized. The review will follow PRISMA and MOOSE guidelines. PubMed/MEDLINE, Embase, Scopus, and Web of Science will be searched from inception using terms for breast cancer, postpartum status, lactation, involution, prognosis, and tumor microenvironment. Eligible studies will be observational (cohort, case–control, cross-sectional) studies of women with breast cancer defining a postpartum subgroup (by time since last childbirth, parity, lactation, or weaning), including a comparator (nulliparous women or longer birth interval), and reporting at least one prognostic outcome (overall, distant metastasis-free, or disease-free survival, or recurrence), an aggressive clinicopathological feature, molecular/immune profile, or a treatment response. We will exclude experimental studies without human endpoints, risk-factor/incidence studies, reviews, and case reports. Two reviewers will independently screen, extract data, and assess risk of bias using the Newcastle–Ottawa Scale. If ≥3 studies report comparable estimates for the same exposure–outcome pairing, we will perform a random-effects meta-analysis using restricted maximum likelihood; random-effects models were pre-specified because of anticipated clinical and methodological heterogeneity. If <3 studies are available, findings will be synthesized narratively. Sensitivity analyses may fit a fixed-effect model, but this will not replace the primary random-effects analysis. Heterogeneity will be assessed with I² and Cochran’s Q, with I² informing interpretation rather than model choice.
Keywords
Journal of Integrated Maternal and Pediatric Care