Tamoxifen breast cancer drug changes hands

Image copyright Getty Images Image caption Namesakes Curzon and Curly have already been reissued

The development of a new variation of the cancer-causing variant of tamoxifen means that it will be harder to prescribe the drug to treat breast cancer.

Covidion, the pharmaceutical company behind the new version, says that the cheaper product also works better and lasts longer.

The debate over whether it is better for patients is yet to be fully decided, although experts have urged people to wait until the trials have been conducted.

Dr Kat Arney, deputy chief medical officer at Breast Cancer Care, said: “Now that we know this new version of tamoxifen does not have any noticeable side effects, it’s important that all patients are given the opportunity to take part in clinical trials.”

How is it different?

Treatments such as chemotherapy and tamoxifen interfere with the action of a molecule called the human epidermal growth factor receptor 2 (HER2) which plays a role in the growth of breast cancer cells.

Chemotherapy, which can include DNA-damaging drugs, kills the cancer cells, but it takes a lot of energy, which can result in a decrease in lifespan for patients.

When cancer cells develop receptors that are less powerful than HER2, they become resistant and multiply.

When the drugs tamoxifen and raloxifene, which causes a decrease in sex drive, are taken together they make it impossible for cancer cells to respond to HER2 and thereby turn them into “functionally sensitive” cells.

Image copyright Getty Images Image caption The new version targets a receptor type to extend the lifespan of the drug in patients

This means that the cells survive and grow and women with common forms of the disease who suffer from these conditions may benefit most from the combination therapy.

Why is this important?

Tamoxifen has been in use in women since the mid 1980s as an alternative to surgery and chemotherapy and has been prescribed in about one in every three breast cancer patients who are diagnosed.

It has proven to be highly effective, but the effectiveness has dropped slightly as the pharmaceutical company Roche introduced an improved version in the late 1990s, called Herceptin.

When a patient takes tamoxifen for five years, the two drugs both work in the same way and stop the growth of HER2, but the new version makes it work well for longer.

Roche confirmed in September that the combination of the two drugs could prolong lifespan by up to 15 months.

Similar but less effective drugs still have side effects, which could well include weight gain, serious anaemia and cardiac conditions, although doctors expect the best outcomes from taking the newer combination therapy.

How many women will be prescribed the new drug?

There are an estimated 300,000 breast cancer patients in the UK, meaning that the new drug could benefit up to 4% of them.

But it is still not known how many women will be eligible to trial the new treatment, because the trials must now be held for all patients who have been prescribed tamoxifen for more than five years.

Tamoxifen has traditionally been more widely prescribed to women with advanced disease because their breast cancer often has been resistant to chemotherapy. The new treatment could theoretically work for a much larger number of women.

Image copyright Getty Images Image caption Can surgery, as previously known, be a viable option for many women with cancer?

How are the experts reacting?

Leading geneticist Prof Eric Winer from the Breakthrough Breast Cancer think-tank said: “The fact that this discovery is better at preventing cancer than it is at killing the cancer cells means that it’s even more important that we get enough patients in clinical trials to confirm whether or not this can be a truly effective treatment for women.”

Patients and relatives of those who have been diagnosed will be able to claim financial support for the treatments they are prescribed, but this may not extend to the new drug.

It is likely that the use of a combination of different types of drugs – in this case the two most effective treatments, tamoxifen and raloxifene – will stop being widely used by about 2025.

In America, the drug was used in the first two doses of chemotherapy, but not by patients for the subsequent three months.

The use of raloxifene was restricted because of the possible side effects of sexual dysfunction associated with it. It was once available on the NHS for other cancer treatments, but has since been withdrawn.

What will happen next?

Chemotherapy and hormonal therapy are still available in Britain, but patients will no longer be able to receive the combination of these drugs unless they have a marked change in their condition.

Omic

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