This analysis evaluated associations between reproductive factors and the expression of stromal fibroblast activation markers in benign breast tissue from women with biopsy-confirmed benign breast disease (BBD) within the Nurses’ Health Study II (NHSII). The stromal markers assayed were αSMA, TNC, FAP, S100A6, and MMP14. Immunofluorescence on tissue microarrays quantified percent positivity per core. Generalized linear regression was applied to log-transformed marker positivity to assess associations with reproductive exposures collected prospectively via biennial questionnaires. In multivariable models, nulliparous status showed a suggestive positive association with TNC expression (β = 0.79; 95% CI −0.10 to 1.68; p = 0.08), while categorical age at menarche showed a suggestive positive trend for MMP14 (p-trend = 0.07). No significant associations were reported for number of children, age at first birth, breastfeeding, continuous age at menarche, time between menarche and first birth, or time since last birth with expression of these stromal markers. The authors state that further studies are needed to confirm these observations.
Reproductive factors such as parity, age at first birth, breastfeeding, and age at menarche are well-established modifiers of breast cancer risk and are also linked to mammographic breast density and breast tissue composition. The breast stroma — including resident fibroblasts and extracellular matrix — plays key roles in tissue structure and signaling and may modulate carcinogenic processes. Prior work has suggested fibroblast activation during postpartum involution, and stromal biomarkers have been associated with tumor behavior when assessed in malignant tissue.
This study tested the hypothesis that reproductive factors associated with lower breast cancer risk would be inversely associated with expression of stromal activation markers, while reproductive factors associated with increased risk would show higher expression of these markers, using non-malignant breast tissue from biopsy samples.
Participants were drawn from the NHSII cohort, which recruited registered nurses in the United States who were 25–42 years old at baseline. The study included women with a first diagnosis of biopsy-confirmed benign breast disease. Reproductive histories and other breast cancer risk factor data were collected prospectively on biennial questionnaires. The abstract reports inclusion of 694 cancer-free women with biopsy-confirmed BBD; additional selection criteria and detailed sampling procedures are not provided in the available source text.
Five stromal fibroblast-associated markers were selected based on prior links to fibroblast activation and associations with more aggressive tumor features in tumor tissue studies: α-smooth muscle actin (αSMA), tenascin-C (TNC), fibroblast activation protein (FAP), calcyclin (S100A6), and matrix metalloproteinase 14 (MMP14). Immunofluorescence staining was performed on tissue microarrays constructed from benign biopsy material, and percent positivity per core was quantified using inForm v2.6.0.
Generalized linear regression models were used to examine associations between reproductive exposures and log-transformed percent positivity for each stromal marker. Reproductive exposures evaluated included parity (including nulliparity), number of children, age at first birth, breastfeeding, age at menarche (continuous and categorical), interval between menarche and first birth, and time since last birth. The abstract reports multivariable analyses but the specific covariates included in models and model-building strategy were not detailed in the provided excerpt.
Nulliparous status showed a suggestive positive association with TNC expression (β = 0.79; 95% CI −0.10 to 1.68; p = 0.08).
Nulliparity was not associated with expression of αSMA, FAP, S100A6, or MMP14 (all p > 0.10).
No statistically significant associations were observed for number of children, age at first birth, breastfeeding, continuous age at menarche, time between menarche and first birth, or time since last birth with any of the five markers’ expression.
Categorical age at menarche showed a suggestive positive association with MMP14 expression (p-trend = 0.07).
The authors characterize the above findings as suggestive, and emphasize the need for further study to confirm these associations.
The results suggest possible relationships between certain reproductive risk factors and expression of stromal activation markers in non-malignant breast tissue: specifically, a suggestive link between nulliparity and higher TNC expression, and a suggestive trend linking categorical age at menarche with MMP14 expression. These findings are consistent with the study’s hypothesis that reproductive history may influence stromal biology relevant to breast cancer etiology and that stromal markers could represent a mechanistic pathway linking reproductive exposures to risk.
However, most reproductive factors examined showed no association with the five stromal markers measured, and effect estimates reported as suggestive did not reach conventional statistical significance thresholds in the abstract.
The available source excerpt is truncated and does not include full methodological details such as the complete sample selection flow, the covariates adjusted for in multivariable models, assay performance metrics, or detailed numerical results beyond the key estimates reported in the abstract.
The abstract reports 694 participants but additional descriptive characteristics (age distribution, timing of biopsy relative to reproductive events, histologic subtypes of BBD) are not provided in the available text.
Because the full results, sensitivity analyses, and discussion sections are not included in the provided material, readers should consult the full published article for comprehensive methods, complete results, and the authors’ full interpretation.
Using benign breast biopsy tissue from NHSII participants, this analysis found suggestive associations between nulliparity and TNC, and between categorical age at menarche and MMP14, while most reproductive factors were not associated with expression of the five stromal markers examined. The authors conclude that further studies are needed to confirm these observations and to clarify whether reproductive history has durable effects on fibroblast activation in normal breast tissue.