Two Low-Cost, Generic Drugs Could Be More Effective Than Tamoxifen Against Breast Cancer

Tamoxifen has been around for over 50 years — and until 2015, nothing had been proven to be as effective at treating and preventing breast cancer.

But studies published in The Lancet have revealed that two generic, low-cost drugs (that have been in use for other conditions for years!) pack more of a wallop than tamoxifen alone: aromatase inhibitors and bisphosphonates.

Aromatase Inhibitors


Aromatase inhibitors are mainly used by postmenopausal women to help halt estrogen production. They block aromatase, the enzyme responsible for turning androgen (a hormone) into estrogen. This is crucial for women with estrogen receptor positive  (ER+) cancer.

The drug does come with unwelcome side effects, just like tamoxifen does, only with differing degrees of severity. While chances of blood clots and stroke are lower than they are on tamoxifen, they do cause more heart problems and also lead to weakened bones.

Aromatase inhibitors reduce recurrence rates by 30%, just like tamoxifen — and this has been well known for years. However, this new study, part of a collaboration at Oxford with the Early Breast Cancer Trialists’ Collaborative Group, shows that taking the generic drug also reduced the risk of dying from breast cancer by 40% within 10 years of starting treatment (compared to no treatment at all). On Tamoxifen alone, women reduced their risk by 30%.

An incredible glitch in the results is that once the participants heard that aromatase inhibitors could reduce recurrence, many of the participants in the trial bailed on tamoxifen to opt for the aromatase inhibitors. This obviously affected their results, and the researchers speculate that the results would have been even more promising if the women had not switched mid-trial.

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The same research group that looked at aromatase inhibitors also did a study on bisphosphonates. This type of drug is used to help strengthen bones and reduce bone loss for people who suffer from osteoporosis.

The study showed that bisphosphonates reduced the risk of death by 18% in postmenopausal women who took the drug within the first 10 years after diagnosis. Bisphosphonates prevent cancer from spreading to the bones, and in the study, the drug was shown to prevent one out of every six breast cancers.

“It tends to be the discovery of new treatments that grabs the headlines, but it is just as important to maximize the benefit patients get from existing treatments through major, practice-changing studies like this.” -Paul Workman, chief executive of the Institute of Cancer Research in London.



When married together, the two drugs counteract the negative effects that either drug on its own could have. Aromatase inhibitors can often lead to bone loss, but bisphosphonates strengthen bones to reduce risk of fractures — and it also improves survival.

Since two-thirds of women diagnosed with breast cancer are a) postmenopausal and b) have hormone-sensitive tumors, this pair of generic drugs could increase their chances of remaining cancer-free — while also being easier on their bank account.

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