Hormone Blockers/Inhibitors For 15 Years Reduces Risk of Breast Cancer Recurrence

The other day, I read about a study that involved 1,918 patients, which showed the risk for reoccurrence was cut by a third. The experts described it as a “big deal” which will change treatment for millions of women around the world. But they also warned there were risks, including osteoporosis. Before this trial was reported, they knew an aromatase inhibitor after 5 years of tamoxifen sharply reduced disease-free survival events. 

With around 250,000 women being diagnosed with an oestrogen-positive breast cancer in the United States, and globally, 1.7 million women are diagnosed with breast cancer around the world each year, these finds will make a huge impact on breast cancer patients. Around 80% of those cases being fuelled by oestrogen. These cancers have a low but persistent risk of returning years later.

Because of this risk women take drugs such as tamoxifen, to prevent oestrogen feeding breast cells, or aromatase inhibitors, which stop the body making oestrogen, for years after a lumpectomy or mastectomy.

The trial which was carried out on post-menopausal women, doubled aromatase inhibitor treatment from five to 10 years. The data, showed that cancer recurrence was cut by 34%. But many women on the trial had already taken other hormonal drugs (Tamoxifen for 5 years) before starting on aromatase (10 years) inhibitors and benefited from 15 years of treatment.

Aromatase inhibitors are readily available around the world and therefore the results will further improve the outcome of women with breast cancer.

At the end of the study, 95% of women were still cancer-free if they had taken the extra treatment. The results, have been widely praised as significant.

But this won’t be for everyone, many will be low risk and can probably safely stop at five years of aromatase inhibitors, but then we’re talking about a substantial number of women keeping going from five to 10 years. There were side effects to treatment including loss of libido, hot flushes and vaginal dryness. The treatment also increased the risk of osteoporosis and bone fractures.

Experts said it should be a decision between doctor and patient whether to continue.

I think you can say that for millions of women around the world these data will support longer durations of anti-oestrogen therapy. But the balance of risks and benefits meant the drugs would likely be targeted at those whose tumours were most likely to come back.

In general, I would imagine that women who had riskier cancers will look to these data and think they are compelling for continuing on longer durations of treatment out to 10 or 15 years. But they are not at the point of saying women should be on these drugs for the rest of their lives.

This is a really important study that could one day have a major impact on how we use anti-hormone breast cancer treatments.

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