Many women used to take hormone replacement therapy (HRT) to help with the symptoms of menopause, such as hot flushes and tiredness. But a few years ago, a study showed that taking HRT increased the risk of breast cancer, heart attacks and strokes. Many women stopped taking it, and it’s much less widely used now.
During the same research project, researchers also noticed that women seemed more likely to die of lung cancer if they were taking HRT. Oestrogen, one of the hormones used in HRT, seems to help some types of cancer to spread.

The researchers have now gone back to the data from the study, including two and a half years of follow-up information that was recorded after the study stopped, to work out how big the increased risk is.

According to the new study, HRT doesn't seem to increase your risk of getting lung cancer. But if you do get lung cancer, you are likely to die sooner if you've taken HRT.

Women who’d taken HRT lived for just nine months on average after being diagnosed with lung cancer, compared with 16 months for women who hadn't taken HRT. At the end of the eight-year study, 11 in every 10,000 women had died of lung cancer if they'd taken HRT, compared with 6 in 10,000 who hadn’t taken HRT. Most of the difference showed up in a type of lung cancer called non-small cell lung cancer.
Although women taking HRT tended to do worse if they got lung cancer, the risk of getting it was quite low. The women were all between 50 and 79 at the start of the study, and just over 1 in 1,000 of them got lung cancer, whether they’d been taking HRT or not.

How reliable are the findings?

The research doesn’t prove that HRT actually caused an earlier death for women with lung cancer, but it does show a strong link.

The authors say we should be cautious in how we view the results, because only a fairly small number of women developed lung cancer. This makes it harder to draw reliable conclusions.

Where's the study from?

The study is part of a long-running research project called the Women's Health Initiative, carried out by researchers from many US universities and medical centres. It was published in The Lancet.

What does it mean for me?

If you’re considering taking HRT, the new study gives you more information about potential risks. If you smoke, or you smoked heavily in the past, you already have a higher risk of lung cancer than other people. This study suggests that, if you do get lung cancer, it may progress faster if you’ve also taken HRT.

What should I do now?

Deciding whether to have treatment for symptoms of menopause can be tricky. Talk to your doctor. He or she should be able to help you weigh up the risks and benefits.
Remember that smoking is the main cause of lung cancer, and also increases your risk of many other types of cancer, heart disease, and lung disease.