10 Years On Tamoxifen Halves Breast Cancer Recurrence Risk

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Main Category: Breast Cancer
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Article Date: 03 Jun 2013 - 4:00 PDT
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10 Years On Tamoxifen Halves Breast Cancer Recurrence Risk

Survivors who take tamoxifen for ten years have half the risk of dying from estrogen receptor positive breast cancer, researchers from Cancer Research UK reported at the ASCO Annual Meeting in Chicago, Illinois, USA.

Lead researcher, Dr Daniel Rea reported that the "aTTom" study demonstrated that estrogen receptor positive breast cancer patients who took tamoxifen for longer than five years were much less likely to suffer cancer recurrence or die from the disease. Currently, the recommended period for tamoxifen therapy is five years.

The study involved 6,953 adult females with breast cancer. 580 patients from 3,468 women took tamoxifen for ten years, while 672 of 3,485 patients stopped tamoxifen after five years.

Dr Rea reported that: 25% of the 10-year tamoxifen patients had fewer recurrences of breast cancer than those on just five years of therapyThere were 23% fewer deaths in the 10-year tamoxifen groupDr Daniel Rea, who is based at the University of Birmingham, England, said:

"These results are important as they establish that giving tamoxifen for longer than the current standard of five years significantly cuts the risk of breast cancer returning.

Doctors are now likely to recommend continuing tamoxifen for an extra five years and this will result in many fewer breast cancer recurrences and breast cancer deaths worldwide. Tamoxifen is cheap and widely available so this could have an immediate impact."

Approximately three-quarters of all breast cancers are of the estrogen receptor positive kind. This type of breast cancer benefits from hormone therapy. Estrogen, a female hormone, encourages breast cancers to grow by activating estrogen receptors. Tamoxifen works by blocking these receptors, thus making it much harder for the cancer to recur after surgery or invade the other breast.

Tamoxifen side effects - patients on tamoxifen may experience menopausal-type symptoms, including hot flashes (UK: hot flushes) and night sweats. A Norwegian study found that acupuncture reduces menopausal symptoms in tamoxifen patients by 50%. More rarely, tamoxifen has also been linked to an increased risk of developing blood clots, endometrial cancer and stroke.

Stroke risk did not rise with 10 years of tamoxifen therapy compared to five years, the researchers found. However, the risk of endometrial cancer did increase. Fortunately, endometrial cancer is usually diagnosed in the early stages of the disease, when it can be treated successfully.

According to the researchers, thirty breast cancer deaths would be prevented for every endometrial cancer death due to long-term tamoxifen therapy.

Professor Richard Gray, who is based at the University of Oxford and was also presenting the aTTom trial results at ASCO, said:

"Five years of tamoxifen is already an excellent treatment but there have been concerns that giving it for longer might not produce extra benefits and could even be harmful. The aTTom study establishes that the benefits of taking tamoxifen for longer greatly outweigh the risks.

Kate Law, director of clinical research at Cancer Research UK, said: "Large clinical trials like aTTom are vitally important to understand how drugs such as tamoxifen work and how best to use them. We need these sorts of studies so we can be sure the benefits from cancer drugs outweigh the side-effects that they may have."

The aTTom trial was funded by the Medical Research Council, UK.

A trial led by Oxford University's Clinical Trial Service Unit reported in The Lancet (December 2012 issue) that taking tamoxifen for ten years after breast cancer surgery is more effective than five years. The study was called ATLAS.

Written by Christian Nordqvist
Copyright: Medical News Today
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Weighing the Risks and Benefits of Tamoxifen and Raloxifene for Breast Cancer Prevention

Researchers have developed a tool that can help guide decisions about which drug—tamoxifen or raloxifene (EvistaR)—is the best choice for breast cancer prevention in high-risk postmenopausal women. These results were published in the Journal of Clinical Oncology.???

Drugs that block the effects of estrogen have been shown to reduce the risk of breast cancer in women at high risk of the disease. Two drugs that have been approved for breast cancer risk reduction in certain groups of women are tamoxifen and raloxifene. Tamoxifen is approved for breast cancer risk reduction in women who are at high risk of the disease (including high-risk premenopausal women). Raloxifene—originally approved for the prevention and treatment of osteoporosis—is approved for breast cancer risk reduction in postmenopausal women with osteoporosis or postmenopausal women at high risk of breast cancer.??

To help postmenopausal women and their healthcare providers evaluate the likely effect of each drug, researchers developed a benefit-risk index. In addition to considering the extent to which each drug reduced breast cancer risk, the researchers also assessed other health outcomes, such as bone fractures, blood clots, stroke, and endometrial (uterine) cancer.???

The researchers found that the risks and benefits of tamoxifen and raloxifene vary by a woman’s age, race/ethnicity, risk of breast cancer, and whether the woman has had a hysterectomy.????

The researchers write “By combining this information with information on clinical features and personal preferences, the health care provider and patient can make an informed decision.” The researchers provide tables to help specific subgroups of women evaluate the likely benefit (or harm) of each drug.?

Women who have a high risk of breast cancer as a result of their family or personal medical history may wish to talk with their doctor about ways to reduce their cancer risk.?

Reference: Freedman AN, Yu B, Gail MG et al. Benefit/risk assessment for breast cancer chemoprevention with raloxifene or tamoxifen for women age 50 years or older. Journal of Clinical Oncology. Early online publication May 2, 2011.?

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Tamoxifen and Raloxifene Both Decrease Breast Cancer Risk

?Among postmenopausal women at increased risk of breast cancer, use of either tamoxifen (NolvadexR) or raloxifene (EvistaR) can substantially reduce the risk of breast cancer. The reduction in risk was somewhat greater with tamoxifen (50% versus 38% with raloxifene), but women treated with tamoxifen were also more likely to experience certain serious side effects. These results were published in Cancer Prevention Research.

Drugs that block the effects of estrogen have been shown to reduce the risk of breast cancer in women at high risk of the disease. Two drugs that have been approved for breast cancer risk reduction in certain groups of women are tamoxifen and raloxifene. Tamoxifen is approved for breast cancer risk reduction in women who are at high risk of the disease (including high-risk premenopausal women). Raloxifene—originally approved for the prevention and treatment of osteoporosis—is approved for breast cancer risk reduction in postmenopausal women with osteoporosis or postmenopausal women at high risk of breast cancer.

To directly compare raloxifene to tamoxifen in the prevention of breast cancer in high-risk women, researchers conducted a clinical trial known to as the STAR trial (The NSABP Study of Tamoxifen and Raloxifene [STAR] P-2 Trial). The study enrolled more than 19,000 postmenopausal women at increased risk of breast cancer. Women were assigned to receive either tamoxifen or raloxifene daily for five years. Study participants have now been followed for a median of 6.8 years.

Initial results from the trial indicated that raloxifene and tamoxifen were similarly effective at reducing the risk of invasive breast cancer—both drugs reduced risk by roughly 50%. Raloxifene appeared to be somewhat less effective, however, at reducing the risk of noninvasive breast cancers such as ductal carcinoma in situ (DCIS).

More recent, longer-term results indicate that as women in the study completed five years of the drugs and stopped taking them, tamoxifen continued to reduce the risk of invasive and noninvasive breast cancer by roughly 50% compared with a roughly 38% reduction in risk with raloxifene.

Study participants who took raloxifene had fewer serious side effects than study participants who took tamoxifen, both initially and after longer-term follow-up. Side effects that were less common in women treated with raloxifene than women treated with tamoxifen included uterine cancers, blood clots, and cataracts.

The results of this study demonstrate that both tamoxifen and raloxifene reduce the risk of breast cancer in postmenopausal women at increased risk of the disease. Women at elevated risk of breast cancer as a result of family history or other characteristics may wish to talk with their doctor about the risks and benefits of using one of these drugs to reduce breast cancer risk.

Reference: Vogel VG, Costantino JP, Wickerham DL et al. Update of the National Surgical Adjuvant Breast and Bowel Project Study of Tamoxifen and Raloxifene (STAR) P-2 Trial: Preventing Breast Cancer. Cancer Prevention Research [early online publication]. April 19, 2010.?

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Oncotype DX® Predicts Recurrence Risk in Node-negative and Node-positive Breast Cancer Treated with Tamoxifen or Arimidex

Oncotype DXR Predicts Recurrence Risk in Node-negative and Node-positive Breast Cancer Treated with Tamoxifen or Arimidex
Among postmenopausal women with early, hormone receptor-positive breast cancer treated with either tamoxifen (NolvadexR) or ArimidexR (anastrozole), the Oncotype DX test predicts the risk of distant cancer recurrence in both node-negative and node-positive patients. These results were published in the Journal of Clinical Oncology.

Oncotype DX is a genomic test that has been shown to predict the likelihood of distant cancer recurrence and the likelihood of chemotherapy benefit in women with early-stage, estrogen receptor-positive breast cancer that is treated with tamoxifen. The test evaluates the activity of 21 genes from a sample of the patient’s cancer to determine the patient’s Recurrence Score. The higher the Recurrence Score, the higher the risk of cancer recurrence. Oncotype DX has been added to U.S. medical guidelines for early-stage breast cancer.

The current analysis assessed how the Recurrence Score performed among women treated with the aromatase inhibitor drug Arimidex and among those with node-positive breast cancer.

The researchers collected information from 1,231 women who participated in the ATAC (Arimidex, Tamoxifen, Alone or in Combination) study. The study enrolled postmenopausal women with early, hormone receptor-positive breast cancer. Study participants received hormonal therapy with either tamoxifen or Arimidex.

The Recurrence Score (RS) predicted the risk of distant cancer recurrence among women with node-negative and node-positive breast cancer:

Among women with node-negative breast cancer, nine-year risk of distant cancer recurrence was 4% among women with a low Recurrence Score, 12% among women with an intermediate Recurrence Score, and 25% among women with a high Recurrence Score.Among women with node-positive breast cancer, nine-year risk of distant cancer recurrence was 17% among women with a low Recurrence Score, 28% among women with an intermediate Recurrence Score, and 49% among women with a high Recurrence Score.

The relationship between Recurrence Score and risk of distant cancer recurrence was similar regardless of the type of hormonal therapy that the women received.

This study suggests that the Oncotype DX test provides information about risk of distant cancer recurrence in both node-negative and node-positive, hormone-receptor positive breast cancer. Furthermore, Oncotype DX was predictive of distant recurrence risk among women treated with tamoxifen as well as women treated with Arimidex.

Reference: Dowsett M, Cuzick J, Wales C et al. Prediction of risk of distant recurrence using the 21-gene recurrence score in node-negative and node-positive postmenopausal patients with breast cancer treated with anastrozole or tamoxifen: a TransATAC study. Journal of Clinical Oncology [early online publication]. March 8, 2010.

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Femara Results in Lower Risk of Breast Cancer Recurrence Than Tamoxifen

Among postmenopausal women with early-stage, hormone receptor-positive breast cancer, five years of hormonal therapy with FemaraR (letrozole) results in a lower risk of cancer recurrence than five years of tamoxifen. These results were published in Lancet Oncology.?

The majority of breast cancers are hormone receptor-positive. These cancers are stimulated to grow by the circulating female hormones estrogen and/or progesterone. Treatment of hormone receptor-positive breast cancer often involves hormonal therapies that suppress or block the action of estrogen. These therapies include tamoxifen as well as drugs known as aromatase inhibitors, such as Femara. Tamoxifen acts by blocking estrogen receptors, whereas aromatase inhibitors suppress the production of estrogen in postmenopausal women.?

The Breast International Group (BIG) 1-98 Trial is a Phase III clinical trial involving over 8,000 postmenopausal women with hormone receptor-positive early breast cancer. The women were assigned one of four different approaches to hormonal therapy:??

Five years of tamoxifen?Five years of Femara?Two years of Femara followed by three years of tamoxifen?Two years of tamoxifen followed by three years of Femara?

Previous results from this study showed that five years of Femara resulted in a lower risk of breast cancer recurrence than five years of tamoxifen, and that sequential treatment with the two drugs (Femara followed by tamoxifen or tamoxifen followed by Femara) did not appear to be superior to Femara alone.??

Study participants continue to be followed in order to assess longer-term outcomes. The women have now been followed for a median of just over eight years.?

At eight years, the percentage of women alive and free of cancer was 73.8% among women assigned to five years of Femara and 70.4% among women assigned to five years of tamoxifen.?Overall survival was 83.4% among women assigned to five years of Femara and 81.2% among women assigned to five years of tamoxifen.?Sequential treatment with Femara and tamoxifen did not appear to be more effective than Femara alone.?

For postmenopausal women with hormone receptor-positive breast cancer, these results continue to suggest that five years of Femara is more effective against breast cancer recurrence than five years of tamoxifen. Sequential treatment with the two drugs may be a useful strategy for some women.?

Reference: Regan MM, Neven P, Giobbie-Hurder A et al. Assessment of letrozole and tamoxifen alone and in sequence for postmenopausal women with steroid hormone receptor-positive breast cancer: the BIG 1-98 randomised clinical trial at 8.1 years median follow-up. Lancet Oncology. 2011;12:1101-1108.?

Posted November 9, 2011

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