What does PR stand for?

Researchers led by Carol Rosenberg of Boston University analysed 415 breast cancer cases and noted the number of "triple negative" tumours, so called because three critical proteins -- estrogen and progesterone receptors, and the HER2 gene -- malfunction.

They looked at clinical features particularly patient age, weight and race/ethnicity, and pathological features including the triple-negative pattern - tumours that lack expression of the estrogen receptor, the progesterone receptor and the HER2 gene.

Node positivity of four or more lymph nodes and lack of oestrogen and progesterone receptors were associated with a worse overall survival (HR: 2.

Analyses were further stratified by the combined estrogen and progesterone receptor (ER/PR) status of the tumors.

2) In addition, male and female breast cancers differ in regards to expression of steroid hormone receptors (men are more likely to have estrogen and progesterone receptor positive tumors), (2) molecular markers (CerbB-2 and BCL-2 protooncogenes may have no prognostic significance in men, while in women it is associated with poor and favorable prognosis, respectively), (3) and genetics (as in women, men with BRCA-2 mutations are predisposed to develop breast cancer but BRCA-1 mutation does not seem to be a risk factor for breast cancer in men, although it has been described in affected men).

Normally, after a progesterone receptor transmits a growth signal, the cell destroys the receptor, Lee says.

But because the tumour was oestrogen and progesterone receptor negative, it would not respond to the usual breast cancer drugs.

The protective effect of physical activity was most significant against the risk of developing the more aggressive estrogen receptor (ER)-positive, progesterone receptor (PR)-negative form of breast cancer, providing a 34% reduction in risk, said Dr.