Breast cancer drugs should be given for 10 years, study shows

Published 7 Jun 2016

Women should be offered 10 years of drugs to prevent the return of breast cancer, rather than five as now, according to a major study showed longer-term treatment reduced the numbers whose disease came back.

Huge numbers of women in the UK and around the world are already taking hormone therapy – drugs that block oestrogen in the body that can fuel breast cancer growth. Many abandon them within the first few years because of the side-effects or because they feel well and do not want to be on medication.

But the study published in the New England Journal of Medicine and presented at a major cancer drugs conference in Chicago could lead to doctors offering aromatase inhibitors, the class of drug taken by most women following their breast cancer treatment, to their patients for an entire decade.

Most of the 40,000 women a year in the UK with the commonest form of cancer, known as oestrogen receptor positive, are prescribed aromatase inhibitors if they are postmenopausal and the older British drug tamoxifen if they have not reached the menopause. The drugs have different side-effects: tamoxifen can bring on menopausal symptoms such as hot flushes, nausea, low libido and mood swings but aromatase inhibitors can cause joint pain and brittle bones, leading to fractures.

Studies have already shown that women taking tamoxifen for 10 years have fewer recurrences of their cancer than those on the drug for five years. But aromatase inhibitors have been shown to be more effective and are now more widely used.

The study by Dr Paul Goss of Massachusetts general hospital and colleagues was presented at the American Society of Clinical Oncology annual meeting. It enrolled 1,918 women, some of whom took an aromatase inhibitor called letrozole for 10 years, while the rest were given placebo pills. Some had already been on tamoxifen for up to five years. That meant some of the women in the trial took hormone therapy for 15 years in total while others were on it for 10.

Significantly fewer of those who were on letrozole for 10 years had either a recurrence of their cancer or a new cancer in the other breast, although the numbers were small – 67 on letrozole compared with 98 on placebo – which is a reduction of 34%. But 10 years of the drugs made no difference to survival. When cancer did recur, it was usually at stage four and fatal, said Goss.

Goss believes the findings should change practice. He said: “Aromatase inhibitors are now readily available around the world and therefore our results will further improve the outcome of women with breast cancer globally. It will help tens of thousands of women. It will have an enormous impact.”

A further study by the Oxford-based Early Breast Cancer Trialists Collaborative Group, also presented at ASCO, found that there was a real risk of cancer returning up to 20 years after hormone treatment was started. The group analysed the outcomes for 46,000 women from 91 trials who had taken some form of hormone therapy for five years after their breast cancer treatment.

The researchers found that even women with the smallest, least invasive cancers had a 14% risk of recurrence after 20 years and the chances of cancer returning for those with more severe disease rose as high as 47%, suggesting that five years of drug therapy is not enough.

Cancer charities welcomed the findings on aromatase inhibitors, but some experts said women might still choose to stop after five years. “The good news is that we have the data and now women and their medical teams can have an informed discussion,” said Dr Harold Burstein of the Dana-Farber Cancer Institute and on ASCO’s breast cancer committee.

He thought women who were at higher risk of cancer returning because they had experienced more invasive disease in the first place might be more inclined to stay on the drugs for longer. “For lower-risk patients, the benefits are narrow enough that they may opt against it,” he said. In his own clinic, some women have the date when five years is up ringed on the calendar, he said, because they are keen to stop.

The women in the trial who took the drugs for 10 years were probably those who suffered fewer side effects from the start, the paper said.

A considerable number of women stop. A study in Scotland in 2013 found only half of those taking either aromatase inhibitors or tamoxifen were still picking up their prescriptions for the tablets by the end of five years. It also found that those who stopped within three years were more likely to die of breast cancer.

Delyth Morgan, chief executive at Breast Cancer Now, said there was a need for a better understanding of the quality of women’s lives before they were asked to take the drugs for 10 years. “This is a really important study that could one day have a major impact on how we use anti-hormone breast cancer treatments,” she said. “But while this trial showed short-term benefits for patients by doubling the course of standard treatment, we now need to understand the long-term impacts on their survival. How this treatment extension might affect a patient’s quality of life also needs to be investigated before we can consider asking women to live with the side-effects of treatment for an additional five years.”

6 comments

suzyq39

on 30/12/2016

I do don't understand the paragraph starting "significantly fewer those" it doesn't make sense. Can someone explain ? Thanks Sue

maddoglady

on 04/01/2017

I think it means of the 1918 women in the study, those who took letrozole for 10 years, compared to those who took it for 15, had a recurrence or new tumour! You're right though Suzyq39 it isn't very clear. I would say though, I don't think these studies are always terribly helpful. I've been taking Herceptin since 2012 as my Oncologist is of the opinion that it's better to be safe than sorry, he's told me I'll be taking it for an indefinite period. I must admit I'd rather take it than not, if my cancer comes back it won't be good news!

suzyq39

on 07/01/2017

Thanks for that Maddoglady. I wish they would read what they write so it is easy to understand. There is so much conflicting information that it is hard to know what is the right decision to make on your own treatment options. I am glad you feel that your oncologist is helping you with your decision. I have been today to see the doctor that was coordinating the radiation, he is really nice and always answers all your questions, treats you like a person and not a number! Good luck with your treatment. Are you having any side effects from the Herceptin?

maddoglady

on 07/01/2017

Hi Suzyq I do get side effects with Herceptin but to be honest it varies from week to week so I've become quite used to them now. The worst side effect from it is the effect it can have on the heart, however I have ecg scans periodically and so far so good. It has affected my eyesight oddly enough in that it affects the way my eyes focus. It can also cause runny eyes and nose and General flu like symptoms, such as aches and pains, but it isn't all the time. I can go for weeks and feel absolutely fine and then I might get a day or two when I feel really rubbish. Still I'd rather have that than have the cancer come back.

You are very lucky that your oncologist is so forthcoming, I've had a five year battle with mine to discuss my treatment openly. I'm one of those annoying people who likes to know stuff about stuff and then make an informed decision, he subscribes to the "there, there you're doing ever so well, don't worry you're pretty little head about it, we'll decide what's best" it's led to some very interesting and heated exchanges, but he's learning!

Hope everything is going well for you.

suzyq39

on 08/01/2017

Hi Maddoglady - thanks for you reply. Like you I asked loads of questions and even taped the appointment to make sure I had all the information. As you say some are very matter of fact about stuff and think you shouldn't ask questions about your own body!! I think a lot just of patients find all the information mind blowing and don't ask questions. I even asked the doctor if he would have radiation and he just avoided it saying that he wasn't in my situation. I am also not impressed with the so called "prevention" no one seems to be interested just wants your donations to line the drug companies pockets. Apologies if this sounds awful but that's what I have come across. Speak soon and take care and keep well xxx

You will also like

Breast cancer

World Cancer Day: Facts and Insights!

4 Feb 2019 • 8 comments

Read the article

Breast cancer

Telling patients to 'fight' cancer puts them under pressure

4 Oct 2018 • 11 comments

Read the article

Breast cancer

Lung cancer destroyed with tea leaf nanoparticles

21 May 2018 • 8 comments

Read the article

Breast cancer

Revisting a Breast Cancer patient one year later

23 Oct 2018 • 5 comments

See the testimonial

Fact sheet

Breast cancer

Breast cancer drugs should be given for 10 years, study shows

6 comments

You will also like

Most commented discussions

Fact sheet