Breast cancer is not a single disease anymore. There are multiple sub types and depending on various factors, the prevalence of a particular sub type differs from region to region. Based on how aggressive the cancer is, they are classified into –
In situ carcinomas – are cancers that develop from one part of the breast but do not spread to other parts of the breast or body. They are generally not aggressive and can be removed by surgery.
Invasive carcinomas – as the name suggests, they are cancers that are very aggressive because they start from one part of the breast and spread to different parts of the body. If these tumours are detected at an early stage, they can be removed by surgery followed by chemotherapy if required. But if it goes undetected until a later stage, rates of survival even after surgery, chemotherapy and/or radiation therapy are low.
Another important form of classification is based on how the composition of the cancerous cells in terms of the DNA and proteins is altered. The major sub-types under this classification are –
Eliyatkin, N., Yalcin, E., Zengel, B., Aktas, S., & Vardar, E., Molecular classification of breast carcinoma, J. Breast Health 11, 59-66 (2015)