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Jun 21, 2019 02:24PM
Well, LCIS is very hard to study. We can't look at a spot of LCIS in a breast and monitor it over time, because you can't tell that its LCIS unless you look at the tissue under the microscope, which, of course, involves removal or at least a disturbance of the area.
They do know that when classic LCIS women go on later to get invasive breast cancer, the area that the invasive breast cancer grows sometimes/often previously looked normal under imaging.
In this paper, they state These data, further strengthened by the molecular data discussed above, support LCIS being both a nonobligate precursor and a marker for increased risk of developing invasive carcinoma. https://www.archivesofpathology.org/doi/10.5858/ar...:rid:crossref.org&rfr_dat=cr_pub%3dpubmed A nonobligate precursor means that sometimes an LCIS area actually turns into invasive breast cancer. A marker for increased risk of developing invasive carcinoma means that if you find LCIS anywhere in a breast, the entire breast is at increased risk of breast cancer. When LCIS people later get invasive breast cancer, sometimes the invasive breast cancer is genetically related to the previous LCIS, but in other patients, or in other breast cancers in the same patient, the invasive cancer isn't genetically related to their previous LCIS.
So LCIS people are more likely to get invasive lobular carcinoma than the general population (presumably these are cases where LCIS developed into invasive lobular carcinoma), but still most LCIS women go on to get invasive ductal carcinoma (like the general population), thus a sizable number of LCIS patients get cancers that are less genetically related to their LCIS. (Roughly 80% of the general population of invasive breast cancer patients get invasive ductal carcinoma, whereas in LCIS patients its more like ROUGHLY 60% ductal. These numbers vary quite a bit from study to study.) Since LCIS is less genetically related to invasive ductal carcinoma than invasive lobular carcinoma, presumably more of these IDC cases are due to the LCIS acting like a risk factor.
Because LCIS can act like a risk factor for the entire breast, just removing the known areas of LCIS won't eliminate all of the increased risk. I suppose theoretically it might reduce the chance of that spot of LCIS genetically developing into an invasive breast cancer, but since most LCIS people have multiple spots of LCIS, and often in both breasts, and many/all of these LCIS spots are undetectable, you can't remove all the LCIS in a breast, except perhaps in a mastectomy. (Even a mastectomy doesn't remove all breast tissue.) Obtaining negative surgical margins in excision specimens for classic LCIS is not necessary or recommended. https://www.archivesofpathology.org/doi/10.5858/ar...:rid:crossref.org&rfr_dat=cr_pub%3dpubmed
On the other hand, if you have florid or pleomorphic LCIS, then those types are thought to be more aggressive. Since florid and pleomorphic LCIS is less common than classic LCIS, they know even less about them.
Hope this gives you an idea about the uncertainty and controversy concerning LCIS treatment. I've seen papers that recommend that if a person has both an invasive breast cancer and LCIS, if the invasive breast cancer is treated normally, they don't have any worse outcome than people who 'just' have a comparable invasive breast cancer. But I'm sure those opinions are controversial too.
Classic LCIS.If knowledge can create problems, it is not through ignorance that we can solve them- Isaac Asimov
12/8/2005, LCIS, ER+/PR-
1/24/2006 Lumpectomy: Left
7/15/2006 Tamoxifen pills (Nolvadex, Apo-Tamox, Tamofen, Tamone)