(ChemotherapyAdvisor) – The density of collagen 1 fibers (Col1) in breast tumors’ extracellular matrix is associated with lymph node metastasis status and can be imaged using second harmonic generation (SHG) microscopy, according to a study published in the Journal of Biomedical Optics.

“High Col1 fiber density in primary breast tumors is associated with breast cancer metastasis and may serve as an imaging biomarker of metastasis,” reported lead author Samata M. Kakkad of the Johns Hopkins University School of Medicine, Division of Cancer Imaging Research, in Baltimore, MD, and coauthors.

Col1 fibers are “a major structural component” in breast cancer cells’ extracellular matrix, the authors noted.

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In the newly-reported pilot study, they authors compared Col1 fiber density, assessed with SHG microscopy, from breast tumor tissue from patients who had presented with lymph node metastasis (LN+) and those who did not (LN-).

Women with higher Col1 fiber densities are more likely to have LN+.

Using “in-house SHG image analysis software,” to quantify COL1 fiber densities, the authors found COL1 fiber densities to be significantly higher in tumors from patients LN+ at presentation than among those who were LN- at presentation ((fiber volume=29.22%±4.72%, inter-fiber distance=2.25±0.45 μm for LN+ vs fiber volume=20.33%±5.56%, inter-fiber distance=2.88±1.07 μm for LN-), they reported.

“We also demonstrated that tissue fixation and paraffin embedding had negligible effect on SHG Col1 fiber detection and quantification,” the authors added.  

In the future, the method could be used to identify low-metastatic-potential tumors and inform monitoring decisions among patients with breast cancer, to avoid unnecessary lymph node biopsies.

SHG microscopy involves the use of intense laser light to examine <3μm spaces between biopsied collagen fiber tissue.