FISH analysis of collagen deposition and orientation in the breast tissue of 3 np and 3 PPBC women.

Analysis of 11 publicly available microarray datasets of 345 cases≤45 years that relapsed.

Increased collagen deposition in PPBC.

Increased COL1A1 and COX-2 expression that correlated with decreased relapse-free survival.

Analysis of adjacent normal breast tissue from 183 premenopausal women aged 20 to 45 years, grouped by reproductive categories.

Stain for lobular area, lobular composition, apoptosis, and immune cell infiltration.

Increased breast epithelial area in pregnancy and lactation.

Reduced mammary epithelial area in involution <12 months.

Involution is characterized by wound-healing-like tissue remodeling programs that occurs within a narrow time frame (18 months).

Analysis of 38 postpartum and 190 np breast cancer patients≤45 years.

Analysis of lymphatic vessel density in normal adjacent and breast tumor tissue measured by D2−40+vessel count.

Increased lymph node positivity in PPBC patients. No difference in HER-2 or triple-negative cases.

Increased lymphatic vessel density and tumor cell invasion of lymphatics in PPBC patients.

Analysis of SEMA7A in normal breast tissue from biopsy by IHC.

Kaplan–Meier analysis of SEMA7A, PDPN, and CD68 expression in >600 breast cancers, as well as ovarian, lung, and gastric cancer.

Increased expression of SEMA7A in breast tissue from women>5 years involuting.

Decreased distant metastasis-free survival when SEMA7A, PDPN,and CD68 were co-expressed.

Analysis of normal breast tissue from 32 postpartum (up to 10y) and 20 np women aged 18 to 45 years.

LCM, RNA expression, and RT-PCR of 64 selected genes associated with involution.

Upregulated inflammation-associated genes in postpartum women.

Reduced expression of ESR1, PGR, HER2, and higher expression of ESR2 in postpartum women. 14 of 64 genes from RT-PCR were differentially regulated.

Analysis of normal and tumor tissue from 6 np, 9 pregnant, 11 lactating, 8 involuting, and 10 regressed women aged ≤45 years.

IHC, IF, imaging of CD68, CSF-1R, and F4/80.

Increased macrophage number during involution that exhibited an M2-phenotype with expression of IL-4 and IL-13.

Analysis of tumor tissue from 17 recent pregnant, 17 distant pregnant, and 19 np breast cancer patients aged 18 to 45 years.

RT-PCR, IHC,and image analysis.

Different gene expression pattern (8-gene signature) in breast cancers detected in PPBC diagnosed up to 10 years after delivery, mainly attributable to the TNBC subgroup.

Analysis of tumor tissue from 50 postpartum and 7 np breast cancer patients, grouped by reproductive categories.

IHC of IL-10 and FoxP3.

Increased infiltration of IL-10 +and FoxP3 +immune cells in post-lactational human breast tissue suggestive of immunosuppressive microenvironment.

Analysis of tumor tissue from 3 postpartum patients and 3 np breast cancer patients.

Multiplex analysis and TCGA RNAseq analysis

Increased PD-L1 expression and PD-L1 T-cells in postpartum patients.

Observed co-expression of immune inhibitory PD-L1, PDPN,and CD68 in breast cancer TCGA patients.