Our Health Library information does not replace the advice of a doctor. Please be advised that this information is made available to assist our patients to learn more about their health. Our providers may not see and/or treat all topics found herein.

Estrogen and progesterone receptor (ER/PR) tests

Estrogen and progesterone receptor (ER/PR) tests identify whether these hormones affect the way that breast cancer grows. The results of these tests help doctors decide whether to use hormone therapy to help stop the cancer from growing or to lower the risk of the cancer coming back (recurrence).

The hormones estrogen and progesterone attach to certain receptors on the breast cells to stimulate the growth of normal breast cells and some breast cancers.

Breast cancer cells that lack these receptors (ER-negative and PR-negative cancers) are much less likely to respond to treatment with such medicines as tamoxifen or aromatase inhibitors. ER/PR-positive tumors have these receptors and are more likely to respond to treatment with tamoxifen or aromatase inhibitors.

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Travel Warnings and Tips for Pregnant Women

If you decide to vacation, visit old friends, or must travel for work, pregnancy shouldn’t stop you from flying or