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Letrozole versus Tamoxifen to fight breast cancer

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Women fighting breast cancer have better long-term survival rates using a newer drug compared with Tamoxifen, once the standard NHS treatment.

A new study shows letrozole cut the risk of cancer returning by one-fifth, and patients were 21 per cent less likely to die.

The findings confirm that women with early breast cancer taking letrozole, an aromatase inhibitor (AI), for five years after surgery live longer without the disease, compared with Tamoxifen.

‘AIs’ were approved five years ago for postmenopausal women being treated on the NHS but some patients take Tamoxifen initially and switch to an AI drug within two to three years.

New research found women using letrozole, also known as Femara, for the entire five-year period are more likely to survive.

The drop in risk of death was 21 per cent, while there was a 20 per cent reduction in risk of their breast cancer coming back, says a U.S. led study published in The Lancet Oncology.

It is the latest analysis of a trial of 8,000 women carried out in 27 countries including the UK, which assigned women to either letrazole or Tamoxifen or each drug in sequence.

Letrozole

Letrozole

After eight years of follow-ups, women given letrazole alone fared best compared with women taking Tamoxifen alone.

Taking the drugs in turn did not significantly cut the risk of relapse or death compared with letrazole alone.

Lead author Meredith Regan, from the International Breast Cancer Study Group Statistical Center at the Dana-Farber Cancer Institute in Boston, said: ‘This updated analysis shows that letrazole offers long-term protection over Tamoxifen in these patients.’

Around 48,000 British women develop breast cancer each year, including 35,000 after the menopause, and Tamoxifen has been routinely used for 20 years to cut recurrence rates.


AI drugs shut down the body’s supply of oestrogen altogether, while Tamoxifen works by blocking the effect of oestrogen on cancer cells.

These drugs work in women only after the menopause and where breast cells are sensitive to oestrogen – up to four in five cases.

The Government’s rationing watchdog has approved three aromatase inhibitors (AI) – Aromasin, Arimidex and Femara – alongside Tamoxifen and primary care trusts are expected to fund them.

Experts say the latest findings mean AI drugs should now be used in preference to Tamoxifen.

Although AIs can cause problems with bone density, Tamoxifen has a four-fold higher risk of leading to hysterectomy following womb disorders. AIs also cause fewer serious side effects than Tamoxifen such as blood clots and stroke.

Breast and Ovarian cancer progress

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Significant progress is being made in the prevention and treatment of ovarian and breast cancer, according to findings discussed at a global oncology conference.

“The studies presented at this meeting show impressive progress in disease control and prevention of breast cancer,” said Dr. Andrew Seidman, professor of medicine at Cornell University.

“Also, two consistent studies demonstrated the benefit of adding bevacizumab (Avastin) to standard chemotherapy for ovarian cancer,” he added.

Avastin, produced by Swiss biotech giant Roche, blocks the development of blood vessels needed for tumor growth.

A clinical trial showed a 52 percent reduction in the risk of progression of recurrent ovarian cancer in women who took Avastin in combination with platinum-based chemotherapy.

The most striking finding at the 47th annual meeting of the American Society of Clinical Oncology was that Aromasin, which blocks the production of estrogen, reduced by 65 percent the risk of breast cancer in high risk post-menopausal women.

Close to three-quarters of breast cancer tumors need estrogen to grow.

Breast cancer cell

Breast cancer cell

Annually, there are 1.3 million new cases of breast cancer and nearly 500,000 women die worldwide. In the United States, only lung cancer accounts for more deaths in women.

Paul Goss of Harvard Medical School and lead author of the study on exemestane — sold under the brand name Aromasin — said it’s the “first major clinical trial” in the past 10 years on breast cancer prevention.

“Exemestane may be considered a new option for the prevention of breast cancer,” Goss said during a press conference.

The clinical study was conducted from 2004 to 2010 and enrolled 4,560 women from the United States, Canada, Spain and France who had at least one major risk factor such as being age 60 or older, or having prior breast cancer tumors, including breast cancer with mastectomy.

Half the participants received Aromasin, produced by US pharmaceutical giant Pfizer, and half were given a placebo.

After a period of three years, the Aromasin group had about one third as many invasive cancers as those in the placebo group — a result corresponding to what researchers expected at the beginning of the trial, Goss said.

Aromastate inhibitors like exemestane are distinct from other anti-estrogen therapies such as tamoxifen and raloxifene, which have been approved by the US Food and Drug Administration as preventative therapies for women at high breast cancer risk.

Exemestane, too, has been approved by the FDA, for use in early breast cancer patients.


The most common side effects reported by Aromasin users include fatigue, hot flashes, insomnia and joint pain.

Also Saturday, researchers said extra radiation treatment lowers the rate of breast cancer recurring in women who have had tumors surgically removed.

More than 1,800 women participated, receiving whole breast radiation (WBI) alone or WBI along with radiation to the surrounding lymph nodes.

Five years later, women who received radiation treatment to the breast and lymph nodes had a 41 percent lower rate of recurrences near the tumor site and a 36 percent lower rate of cancer recurrences in other parts of the body.

“These results are potentially practice-changing,” said Timothy Whelan, an oncology professor at McMaster University of Canada and lead author of the clinical study.