Estrogen Levels May Determine Breast Cancer Recurrence

It appears that the higher a breast cancer survivor’s level of estrogen is the greater is her risk of developing breast cancer again, according to study published in Cancer Epidemiology, Biomarkers and Prevention. Researchers found that blood tests revealed higher estrogen levels among women whose breast cancer had returned, compared to other breast cancer survivors – this is despite receiving estrogen-blocking medication.

Studies had established a compelling link between estrogen levels and the development of many first time breast cancers, the researchers explained. As there were not many studies showing an association between estrogen levels and breast cancer reoccurrence, especially among patients receiving such estrogen-blocking drugs as Tamoxifen, the researchers decided to investigate this potential link.

The authors say that patients who have survived breast cancer should be extra careful to keep their estrogen levels down, by exercising regularly and maintaining ideal bodyweight.

Lead author, Professor Cheryl Rock, University of San Diego, said “This is the largest study to date and the only one to have included women taking agents such as tamoxifen to reduce estrogen’s effect on cancer growth.”

Tamoxifen therapy has managed to reduce the chances of a breast cancer survivor developing the cancer again by 50%. However, this anti-estrogen medication does not always bring down estrogen levels enough. Rock explained in a telephone interview with Reuters that a patient cannot just assume that because she is taking one drug that has a good effect she should forget about all of the other useful things that she might be able to do to keep estrogen levels down.

In this study, the researchers monitored 3,088 breast cancer survivors who were completely cancer free at the start of the study. 153 women developed breast cancer during the study – they were compared to another 153 women who were cancer free for at least seven years. Their body size, age, ethnicity, body types and chemotherapy use were compared. Approximately two-thirds of them had been on tamoxifen therapy, while 78% had estrogen-receptor positive cancers. An estrogen-receptor positive cancer thrives on estrogen (and does not grow without it).

Estrogen blood levels of women who had breast cancer recurrence were twice as high as those whose breast cancer had not returned, the researchers reported.

Rock and team said that the next step is to find lifestyle modification factors that may benefit beast cancer survivors. Exercise has been shown to lower estrogen levels. Keeping an ideal bodyweight also helps prevent estrogen levels from rising.

The team is currently investigating whether there may be a link between bodyweight and breast cancer recurrence risk.

“Reproductive Steroid Hormones and Recurrence-Free Survival in Women with a History of Breast Cancer”
Cheryl L. Rock, Shirley W. Flatt, Gail A. Laughlin, Ellen B. Gold, Cynthia A. Thomson, Loki Natarajan, Lovell A. Jones, Bette J. Caan, Marcia L. Stefanick, Richard A. Hajek, Wael K. Al-Delaimy, Frank Z. Stanczyk, John P. Pierce, for the Women’s Healthy Eating and Living Study Group
Cancer Epidemiology Biomarkers & Prevention, 10.1158/1055-9965.EPI-07-0761
Click here to see Abstract online

What is Breast Cancer?

Breast cancer is a tumor that has become malignant – it has developed from the breast cells. A ‘malignant’ tumor can spread to other parts of the body – it may also invade surrounding tissue. When it spreads around the body, we call it ‘metastasis’.

A woman’s breast consists of lobules. Lobules are milk-producing glands. The breast is also full of ducts – milk passages that connect the lobules to the nipple. There is also fatty and connective tissue surrounding the ducts and lobules – this is called stroma.

The most common breast cancers start in the cells around the ducts. Others can start in the cells that line the lobules. A smaller number of breast cancers can start in other parts of the breast.

The human body has two ways of moving fluid about. One is through the blood stream, which carries plasma, red and white blood cells and platelets. Lymphatic vessels carry tissue fluid, waste products and infection fighting cells (immune system cells). Immune system cells are located in the lymph nodes – the nodes are shaped like a bean.

It is common for cancer cells to grow in the lymph nodes. They get there via the lymphatic vessels.

The lymphatic system of the breasts connect to the lymph nodes in three areas: Under the arm (axillary lymph node), in the chest (internal mammary node) and by the collarbone (supra or infraclavicular node).

Doctors guess that if cancer cells are in the lymphatic system, they are most likely to be in the bloodstream and will spread to other organs in the body. It is very hard to test for breast cancer cells in the bloodstream.

If breast cancer cells have got to the nodes under the arm (axillary), it will most likely swell. Whether or not it has swollen there, will decide what type of treatment a patient should have. If cancer cells are found in more lymph nodes, then the likelihood of it turning up in different parts of the body is greater. However, there is no hard and fast rule here. Women have had swellings in many nodes and did not develop metastases, while some women with no swellings in their nodes did.

Most breast lumps are benign (harmless)

Although most breast lumps do not develop into anything dangerous (benign) some will need to be biopsied (doctor takes a piece out and tests it). Most lumps are harmless cysts – sacs filled with fluid.

A benign tumor cannot spread to other parts of the body – it stays inside the breast. They pose no threat to the patient’s life. They are not cancer. Some of them, however, can increase the woman’s chance of developing breast cancer later on. Tumors such as papillomas and atypical hyperplasia are examples of this.

How common is breast cancer?

Breast cancer is the most common cancer for women. About one in every nine women will develop breast cancer in her lifetime. 99% of all breast cancers are diagnosed in women, 1% affect men.

In the USA there were 100,000 new cases in 1985. In 1994 the number rose to 180,000. The main reason for the increase is better awareness leading to more diagnostic tests.

Why do some women get breast cancer?

We don’t know the answer to that yet. We know that heredity plays a part. The more close relatives a woman has who had breast cancer, the higher is her risk of developing it.

Written by Christian Nordqvist

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