HRT was touted as the modern-day equivalent of the fountain of youth-until
2002, when the US Women's Health Initiative (WHI) study, one of the
largest-ever studies of these drugs, discovered that women taking HRT were
more likely to have breast cancer, ovarian cancer, stroke and heart disease.
And now, new evidence from the WHI data shows that the use of HRT during the
menopause increases lung cancer by 60 per cent after five years.
Dr Rowan Chlebowski, a medical oncologist at Harbor-UCLA Medical Center in
Los Angeles, CA, analyzed the WHI statistics, and found a link between
prolonged HRT use and non-small cell (NSC) lung cancer.
Although most of the adverse publicity after the WHI study focused on the
breast cancer risk, this is the first time that a link between HRT and lung
cancer has been identified. It also happens that NSC lung cancer is the
leading cause of death in women.
The most vulnerable women were smokers using HRT, who accounted for slightly
more than half of all cases of NSC lung cancer. In the WHI study, the
researchers found one extra death from this for every 100 women using
Prempro, Wyeth's combination oestrogen-progestin HRT drug.
Ovarian cancer risk
This announcement, made at the annual meeting of the American Society of
Clinical Oncology in May, coincided with the release of the findings from a
large-scale, long-term Danish study showing that women who take HRT increase
their risk of ovarian cancer by 38 per cent (JAMA, 2009; 302: 298-305).
The study, which included more than 900,000 women aged 50-79, found that the
current use of hor-mones accounted for a 38-per-cent greater chance of
ovarian cancer. This translates to one extra case every year for every 8300
women using HRT, or 140 extra cases during the eight-year follow-up,
accounting for 5 per cent of all cases of the cancer.
The risk of having the disease were the same regardless of how long the drug
was taken, which formulation was used, how much oestrogen was included in
the mix and what sort of delivery method was chosen.
As ovarian cancer is difficult to detect and is often fatal, such a risk
should not be brushed aside, the Copenhagen researchers noted.
HRT to blame
Up to now, medicine has tended to blame a familial 'predisposition'-that is,
a family history of breast cancer and the presence of certain predisposing
genes-on many inci-dences of breast cancer, particularly in women using HRT.
Nevertheless, the latest trawl through the WHI data shows that HRT shoulders
much of the blame.
Epidemiologists from the Univer-sity of Rochester Medical Center, in New
York, followed-up the more than 16,000 postmenopausal women given either HRT
or a placebo during the five-year WHI study, which was abruptly abandoned
when the health risks emerged. When they evaluated the 349 women who'd
developed breast cancer, they could find no link with a family history.
The researchers concluded that a family history and hormones have
"independent and non-interacting effects"-in other words, the cases of
cancer were most likely entirely caused by HRT (Epidemiology, 2009; 15 May:
doi: 10.1097/EDE. 0b013e3181a71279).
Fewer cases after the facts
Following the disclosures of the WHI trial, breast cancer rates fell by 13
per cent among more affluent women in California, but only by 7 per cent in
rural areas. When researchers from the Northern California Cancer Center
investigated the discrepancy, they found that women in the more rural areas
had not heard about the link between HRT and cancer, and so had continued
taking the drugs-which would again tend to point the finger at HRT (BMC Med,
2009; in press).
After the WHI results were reported, Wyeth's products took a hammering, and
their use declined by 50 per cent. Nevertheless, sales of the oestrogen-only
drug Premarin and various cream formulations still constitute a business
totalling up to one billion dollars per year.
Last month, the US Food and Drug Administration added a final nail in the
HRT coffin with a boxed warning for Prometrium, a progesterone drug, warning
of the WHI's results showing increased risks of heart attack, stroke,
invasive breast cancer, blood clots and deep vein thrombosis, and a greater
risk of dementia, among those taking combined oestrogens and progesto-gens
of any variety.
The current risks of HRT
According to the US Women's Health Initiative study, hormone therapy
increases your chances of developing the following diseases by these
- Coronary heart disease-related events, 29 per cent
- Stroke, 41 per cent
- Deep vein thrombosis, 200 per cent
- Blood clot in lungs, more than 200 per cent
- Invasive breast cancer, 24 per cent
- All cancers among previous users, 86 per cent
- Ovarian cancer, 38 per cent
- Lung cancer, 60 per cent.
Vol. 20 06 September 2009