I’ve written before about the controversy over lobular carcinoma in situ (LCIS) and whether it is just a marker of increased risk or possibly a precursor to invasive carcinoma, like ductal carcinoma in situ (DCIS). The reason it was felt to be just a marker of increased risk was that most early studies showed that women who had LCIS and developed invasive cancer later on had the same risk in both breasts and about half of the invasive cancers were ductal, not all lobular as one might expect if LCIS was a pre-cancer.

Recent studies have cast doubt on those initial findings, suggesting that most of the cancers that develop after a diagnosis of LCIS are in the same breast as the LCIS and the majority are invasive lobular carcinoma. While this data is still “new and emerging” a new research study out this month adds more support to this theory.

A study in the journal Breast Cancer Research looked at LCIS and studied some of the genetic alterations in the cells.  While the study is very complex and geared mostly toward basic scientists studying breast cancer, one interesting finding caught my attention.  This research group found that one particular mass-forming case of LCIS over-expressed a protein called MMP9 (I’ll spare you the long name!).  This protein is thought to be important in the development from in situ to invasive carcinoma because this family of proteins can “eat through” the collagen in the basement membrane of ducts and lobules and allow the cells to invade the surrounding tissue (thus, invasive carcinoma).

While this data is limited, it is very interesting and again raises the possibility that LCIS is more than just a marker of increased risk for the development of invasive carcinoma, but it may be a precursor lesion like DCIS.

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