Medical School Pathology: Breast Cancer Pathogenesis & Classification

This video for medical students describes the pathogenesis of the three major biologic categories of invasive breast cancer ( luminal; HER2; and triple negative) and the morphologic types of breast cancer with a focus on ductal and lobular carcinoma.

[@dolomuse]

What is the implication of IDC without DCIS? Does this imply a lack of local, clonal cellular evolution and suggest breast reseeding from a distant metastatic locus? Thanks so much for this excellent channel!

[@donnadallariva8377]

Thank You so very much for this informative video. I am a breast cancer survivor. And I have been trying to educate myself on invasive Lobular carcinoma which I was diagnosed with in 2016.

[@PathologyCentral]

You're welcome!

[@Army-eu1vu]

Very useful video, thank you!

[@PathologyCentral]

You're welcome!

[@blackwhite5879]

17:42 You talked about germline BRCA1 mutation being responsible for familial cases of ER+ breast cancers and PIK3CA mutation for sporadic cases, but here, they occur together in a sequence. My question is - what mutation takes normal breast tissue to flat epithelial atypia in sporadic cases which, in familial cases, was BRCA1 mutation?

[@PathologyCentral]

Hello. First, to clarify: germline BRCA2 mutations are seen in ER+ breast cancers, germline BRCA1 is seen in triple negative cancers. We left out some of the detail in Robbins & Kumar Basic Pathology, but you can learn more in Robbins & Cotran Pathologic Basis of Disease.The exact genetic lesions leading to flat epithelial atypia are not well defined. It is thought that gains in 1q and loss of 16q precede flat epithelial atypia. The appearance of BRCA2 preceding PIK3CA is simply a limitation of the illustration, trying to show multiple lines of information.

[@blackwhite5879]

@@PathologyCentral Just to be sure...are you saying that 1q gain and 16q loss are mutations leading to flat epithelial atypia in sporadic ER+ breast cancer developement?

[@blackwhite5879]

@@PathologyCentral yes that is BRCA2. Apologies!

[@BrunHenriksen]

In your video you state that medullary carcinomas does not have a better prognosis. Which research do you base this statement on?

[@BrunHenriksen]

Your statement is not in accordance with information provided by ncbi, so I'm a bit confused. Would like to know what kind of research that back up your statement. www.ncbi.nlm.nih.gov/books/NBK542292/ - last update september 26, 2022 (so quite recently).

[@PathologyCentral]

In the video, I state that medullary carcinoma does not have a "good" prognosis. That is in fact, true! Medullary carcinoma has a BETTER prognosis compared to other triple negative carcinomas matched for size and grade. Part of the explanation may be that medullary carcinomas (by definition) are rich in tumor infiltrating lymphocytes, a finding associated with a better response to chemotherapy. The problem has been that oncologists were interpreting a "better relative prognosis" to mean a "good prognosis" which resulted in women with medullary carcinomas not receiving chemotherapy. There were also problems with reproducibility for this diagnosis. Thus, with each edition WHO has deemphasized this term so that now it is considered a "pattern" and not a specific diagnosis. I hope this helps! The WHO has some additional clarifications on the matter.

[@donnadallariva8377]

Where is the video on Breast cancer risks. Couldn't find it

[@PathologyCentral]

Here is the link: kzbin.info/www/bejne/Y4C4Y5qmZ5Vmd7c