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In Breast cancer, Lung is the second most common site of metastasis after the bone. Various
factors are responsible for Lung metastasis occurring secondary to Breast cancer. Cancer cellderived
secretory factors are commonly known as ‘Cancer Secretomes’. They exhibit a prompt role
in the mechanism of Breast cancer lung metastasis. They are also major constituents of hostassociated
tumor microenvironment. Through cross-talk between cancer cells and the extracellular
matrix components, cancer cell-derived extracellular matrix components (CCECs) such as
hyaluronan, collagens, laminin and fibronectin cause ECM remodeling at the primary site (breast) of
cancer. However, at the secondary site (lung), tenascin C, periostin and lysyl oxidase, along with
pro-metastatic molecules Coco and GALNT14, contribute to the formation of pre-metastatic niche
(PMN) by promoting ECM remodeling and lung metastatic cells colonization. Cancer cell-derived
secretory factors by inducing cancer cell proliferation at the primary site, their invasion through the
tissues and vessels and early colonization of metastatic cells in the PMN, potentiate the mechanism
of Lung metastasis in Breast cancer.
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On the basis of biochemical structure, these secretory factors are broadly classified into proteins and
non-proteins. This is the first review that has highlighted the role of cancer cell-derived secretory
factors in Breast cancer Lung metastasis (BCLM). It also enumerates various researches that have
been conducted to date in breast cancer cell lines and animal models that depict the prompt role of
various types of cancer cell-derived secretory factors involved in the process of Breast cancer lung
metastasis. In the future, by therapeutically targeting these cancer driven molecules, this specific
type of organ-tropic metastasis in breast cancer can be successfully treated.
The extracellular matrix protein ITIH5 is a novel prognostic marker in invasive node-negative breast cancer and its aberrant expression is caused by promoter hypermethylation