HRT linked to LC risk

Women who take hormone replacement therapy (HRT) are at an increased risk of developing lung cancer (LC), new research by the Oregon Health and Science University suggests. As published in the 16th February online edition of the Journal of Clinical Oncology (10.1200/JCO.2009.25.9739), women aged 50 to 76 years who take oestrogen plus progestin (O+P) may have an increased risk of the disease.

According to the researchers, although the risk is duration-dependent, with women taking HRT for ten or more years at greatest risk of developing LC, an acceptable length of HRT has yet to be determined. However, it was noted that while the risk of developing LC for women using O+P for ten years or longer was approximately 50 per cent more than women not using HRT, this risk is small compared to the risk from smoking.

The scientists reviewed data collected from 2000 to 2002, and identified 36,588 peri- and postmenopausal participants aged 50 to 76 years who met their study criteria and followed them for six years. At the end of the observation period, December 2007, 344 of the participants had developed LC. After adjusting for smoking, age and other factors that affect the risk of the disease, the researchers determined that the use of O+P for ten or more years was associated with an increased risk for LC, compared with no use of HRT. They also found that the duration of use was associated with an advanced stage of cancer at diagnosis.

This research is not the first to highlight the risk of HRT use with LC. Scientists from the University of California, Los Angeles Medical Center previously reported that HRT using O+P increases the risk of death from LC. After the eight-year total follow-up from the study, published in the 20th September 2009 online edition of The Lancet (10.1016/S0140-6736(09)61526-9), the researchers found that more women died from LC in the combined HRT group than in the placebo group (73 compared to 40 deaths). In other words, women in the HRT group were 71 per cent more likely to die.

Further, it is not just an increased risk of LC that has been linked with HRT. According to results from a Stanford University study, published in the 5th February 2009 edition of the NEJM (2009;360:573-587), postmenopausal women who take combined O+P menopausal hormone therapy for at least five years double their annual risk of breast cancer. This multi-centre study also found that women on HRT can quickly reduce their risks of cancer simply by stopping the therapy.

Research such as this suggests that postmenopausal women, especially current smokers or long-term past smokers, should carefully consider these risks before initiating or continuing combined O+P use.

Alice Rossiter
Editor, Cancer Drug News