https://www.medicalnewstoday.com/articles/320449.php
Breast cancer occurs when breast cells multiply uncontrollably. The excessive cell growth will form into a lump or mass and cause cancer.
Breast cancer usually starts in the inner lining of milk ducts or the lobules that supply them with milk and can spread to other parts of the body.
https://www.medicalnewstoday.com/articles/37136.php
https://www.mayoclinic.org/diseases-conditions/breast-cancer/symptoms-causes/syc-20352470