Reading your Pathology Report: Cancer Size, Lymph Node Involvement, ER and PR Status
More things to look for on your pathology report - my last post on pathology reports covered histology, margins and grade. Other important things a pathologist will consider:
Size of the Breast Cancer (Measured in cm)
This is somewhat an approximation of the size in diameter of a three dimensional tumor - looking for the widest point. Breast cancer can sometimes be shaped oddly - think of a bow turned on itself in which case it would look like two separate focuses of cancer - the skillful pathologist will comment on the actual size and whether the cancer is one site "focus" or many sites (multifocal). The smaller the size of the cancer, the better.
Lymph Nodes (Sentinel and Other)
The most important prognostic feature of breast cancer is still felt to be the involvement of lymph nodes with cancer - the # of involved lymph nodes and some features of lymph node involvement being key.
The sentinel lymph node(s) is/are the "draining" lymph nodes from the cancer and most breast surgeons will retrieve sentinel lymph nodes - if these are normal or "negative" then there is no reason to do a full axillary dissection (and increase the risk of lymphedema).
Lymph nodes are read as positive, now "microscopically positive" - any cancer >0.2 mm is considered a positive node - and the appearance is commented on. Extracapsular extension, or a lymph node filled with cancer and bursting at the seams, is worse than generic lymph node involvement.
You can usually figure out the total number of involved lymph nodes in the pathology report as they will total the number involved as well as the number sampled.
Estrogen Receptor Status
This is usually given as "positive" "+" or "negative" "-" and also a % from 0 to 100 by many pathologists. Estrogen is a circulating hormone and the presence of the receptor in the cancer cells' nucleus implies a better prognosis and also the ability to use hormonal therapy (tamoxifen or aromatase inhibitors) to increase your chance of cure. There is some prognostic significance to a higher % than a lower.
Progesterone Receptor Status
Progesterone receptor is another receptor found in the nucleus which if present is better prognostically - the ER+ PR+ or "luminal" subtype has a very good prognosis relative to other subtypes of breast cancer. Breast cancer can be ER+ PR+, ER+ PR-, ER- PR+ or ER- PR- (in order of decreasing prognosis, i.e. ER- PR- having the worst prognosis - all other things being equal.