Breast cancer classification is used to assess the tumor to decide on treatment and prognosis. Classification can be performed using molecular, immunohistochemical, and clinical characteristics. One of the important classification types is receptor status, because it identifies those cancers that have specific targeted treatments available. Breast cancer tumors have traditionally been classed using immunohistochemistry as one of four types: * eostrogen receptor positive * progersterone receptor positive * HER2 overexpression positive *<unk><unk>  There are targeted therapies for estrogen and progesterone receptor cancers and more recently HER2 receptor cancers but there are no targeted therapies for<unk>  as a whole. The threshold level for hormone receptor positivity was changed in 2010 and now requires more than 1% positive tumor nuclei are found in the tumor sample. Newer techniques for categorising breast cancer are based on gene expression in the tumor which classifies breast cancer into: * luminal A (HR+/HER2-) 68% * luminal B (HR+/HER2+) 10% * HER2 overexpressing (HR-/HER2+) 4% * basal-like (HR-/HER2-) 10% with 7% of unknown subtype. HR indicates hormone receptor and +/- indicates status whether positive or<unk> . The basal-like subtype has many overlapping features to<unk>  and in addition to being receptor<unk> , has increased expression of basal cytokeratins. 85% of basal-like tumors are<unk> . Subtypes are used to try to define better treatments or a more accurate prognosis. However there is no standard classification for<unk>  subtypes. Although<unk>  has a variety of different subtypes that may vary depending on how they are determined, to date the disease is still uniformly treated with chemotherapy although they may have additional targeted treatments. One of the popular subtype classification for<unk>  is: * basal-like 1 (BL1) 35% * basal-like 2 (BL2) 22% * mesenchymal (M) 25% * luminal androgen receptor (LAR) 16% Most of<unk>  is invasive carcinoma of no special type. The following rarer breast tumors have a higher proportion of being<unk> : *adenoid cystic carcinoma 78.2% are<unk>  *metaplastic 76.2% are<unk>  *medullary carcinoma 60.5% are<unk>  *apocrine adenocarcinoma 56.7% are<unk>  *inflammatory 25.9% are<unk>
Triple-negative breast cancer
Hereditary lobular breast cancer
Hormone receptor positive breast tumor
Paget's disease of the breast
Mucinous carcinoma of the breast
Medullary breast carcinoma
Inflammatory breast cancer
Hormone-sensitive cancer