Reviewing medical records may seem like dull work, but it can yield real gold. In the absence of clinical trials, examining patient records can show patterns and trends that might otherwise go unnoticed, such as the fact that long-term use of combined hormone replacement therapy may be associated with an increase in the risk of lung cancer.

Another risk for long-term HRT users

Christopher G. Slatore, MD, of Oregon Health and Sciences University in Portland, was head of the study and his findings particularly relate to peri and postmenopausal women. The risk was seen to increase the longer the woman was on HRT and they confined their research to HRT containing estrogen plus a progestin.

“This study indicates that millions of women remain at risk of developing lung cancer and the highest risk is for those women taking HRT for 10 years or more.” Dr G. Slatore, MD

Interestingly, although smoking is always cited as a major factor in lung cancer it was not found to be a factor here. Whether the women smoked or not did not alter the influence of HRT on lung cancer risk. Dr Slatore confirmed what has been noted in the UK, that HRT use has declined, and he says it is not recommended except for short-term treatment of menopausal symptoms, which I don’t believe is the impression many women are given when they are put on HRT.

In my experience, although the recommended time on HRT is now 5-6 years, I hear often from women who have been on it well in excess of 10 years

Dr Slatore also stated that the link between HRT and lung cancer has a controversial history as studies have shown conflicting results and suffered from limitations such as the inability to evaluate individual HRT formulations. However the amount of data they examined was formidable: 36,588 peri and postmenopausal women aged 50 to 76 who had taken part in the Vitamins and Lifestyle (VITAL) Study had their records examined. The VITAL study examined associations between use of supplements and cancer risk and during six years of follow-up 344 participants developed lung cancer.

About two-thirds of participants were current or former users of HRT and a similar proportion of participants in both groups were current or former smokers. A similar proportion in each group had a personal or family history of cancer.

Dr Slatore concluded that “These findings may be helpful for informing women of their risk of developing lung cancer and delineating important pathways involved in hormone metabolism and lung cancer,” and this should certainly throw up a red flag for women who have been taking HRT long term.