What is Tamoxifen?

Tamoxifen is a pill used for the treatment and the prevention of breast cancer.

Most often it is used for those with early-stage breast cancer and those with metastatic breast cancer whose breast cancer tests positive for estrogen receptors (ER+). Belonging to a group of medications know as Selective Estrogen Receptor Modulators (SERM), tamoxifen is an anti-estrogen and works by blocking estrogen’s effect on breast tissue.

For those with early stage cancer, tamoxifen helps prevent the original breast cancer from returning and also prevents the development of new breast cancer. For those with metastatic breast cancer, tamoxifen helps slow and even stop the cancer from spreading.

Tamoxifen has been used for more than 30 years to treat breast cancer patients. Over the past decade tamoxifen has also been used to reduce the risk of breast cancer in women who are at increased risk of developing prior to a breast cancer diagnosis. Patients diagnosed with ductal carcinoma in situ (DCIS), and patients that carry a genetic predisposition for breast cancer may be candidates for preventive tamoxifen.

Tamoxifen is often given for 5 years and its effects have been shown to be protective for an additional few years even after it’s stopped.

In women who have already had breast cancer, tamoxifen may lower the risk of breast cancer by as much as 40% to 50%.

The Breast Cancer Prevention Trial (BCPT) was designed to study the use of tamoxifen in preventing breast cancer in women with an increased risk of developing this disease. Tamoxifen was shown to lower the overall risk of breast cancer. Estrogen receptor-positive tumors were reduced by 69 percent. However, as expected, there was no reduction in the occurrence of estrogen receptor-negative tumors.

Tamoxifen has side effects. Common side effects are hot flashes, vaginal dryness and vaginal discharge. Some women report irregular menstrual periods, headaches, fatigue, nausea, vomiting and menopausal like symptoms. Much less frequently, tamoxifen can cause serious medical problems - blood clots, deep vein thrombosis, pulmonary embolism, strokes, endometrial hyperplasia, endometrial cancer and cataracts.

Deep Vein Thrombosis (DVT) – A blood clot in the deep veins of the leg, calf and behind the knee.

Pulmonary Embolism (PE) – A blood clot or clots in the lungs.

Endometrial Hyperplasia – An overgrowth of the lining of the uterus the increases the risk of endometrial cancer.

Endometrial Cancer - Cancer of the lining of the uterus.

The risk of developing endometrial cancer is about 2 cases per 1,000 women taking tamoxifen each year compared with 1 case per 1,000 women taking a placebo. Luckily, the majority of the endometrial cancers that occur are found in the early stages and the cancer is cured.

In women taking tamoxifen, physicians closely monitor their patients with routine ultrasound and frequent uterine sampling to detect any changes to the lining. Patients are advised to report any abnormal uterine bleeding.

Tamoxifen has proven beneficial as a breast cancer treatment and in breast cancer prevention. It saves lives. Patients should always discuss the risks any medications are encouraged to discuss these concerns with their doctor.

- Dr. Jonathan Herman, MD
www.LearnAboutHBOC.com