- The estrogen receptor level measured in a primary tumor or in metastases. There are essentially two distinct forms of breast cancer, one that tends to have an early onset and is characterized by an er- status, and one that tends to have a late onset and is characterized by an er+ status. However, these two variants tend to overlap with respect to age, so it is possible for a young woman to have a "late-onset" form of breast cancer and for an older woman to have an "early-onset" variant of the disease.
V86 Estrogen receptor status 
V86.0 Estrogen receptor positive status [er+] convert V86.0 to ICD-10-CM