Sir, - Your edition of July 10th headlined an article: "HRT raises breast cancer risk by 25 per cent study finds. . .research halted early to highlight health risks". Your Medical Correspondent, Dr Muiris Houston, described some of the conclusions of a trial of conjugated equine oestrogens and medroxyprogesterone from the trial reported in the Journal of the American Medical Association (JAMA).
None of the HRT formulations sold in Ireland have the exact same hormone doses but Premique 5 and 10 are the nearest, differing only in their higher progesterone content. The bottom line was that, compared with the control group, an extra 1 per cent of women taking the hormones over the 5.2 years of the trial had either a heart attack, cancer of the breast, uterus or colon, hip fracture or death due to another cause. A similar trial of oestrogen only in women who have had a hysterectomy is continuing.
For every 10,000 women-years, there were seven more heart attacks, eight more strokes, eight more lung clots and eight more breast cancers. There were fewer hip fractures and colorectal cancers but overall there were 19 extra events in that population. The increase in breast cancer risk confirms previous studies on the effects of combination oestrogen/progesterone HRT. The risk of breast cancer after 10 years of oestrogen therapy is increased by 15 to 30 per cent. A 1997 review of data on HRT and breast cancer involving 52,705 women with breast cancer concluded that the increased risk of breast cancer being diagnosed in patients taking HRT disappeared about five years after cessation of use.
If HRT may be damaging to health, where does that leave the oral contraceptive pill? Among women between 35 and 64 years of age, current or former use of the pill was not associated with an increased risk of breast cancer even in women with a family history. Risks from hormone use must be kept in perspective. There is an excess risk of venous clots to the lung of 1 per 10,000 women-years between second and third generation contraceptive pills. Yet the sales of third generation pills such as Femodene, Marviol and Mercilon forge ahead.
Irish death rates from coronary heart disease are the highest in the EU. Because coronary heart disease is the major killer of women in this country, the implications of the JAMA trial are important. In 1995, the conventional wisdom from observational studies suggested a 50 per cent reduction in the risk of heart disease in postmenopausal women who had received oestrogen replacement therapy. Thus, at that time, women whose uteruses were removed appeared to derive major benefit from unopposed oestrogens. Whether that practice survives the results of the current prospective oestrogen-only trial remains to be seen. However, the true risk of HRT for an individual woman may vary greatly because other factors such as blood cholesterol fractions, cancer genes, etc. will tilt the odds in either direction. The future is likely to bring more accurate individual risk prediction.
The JAMA study concluded that this form of HRT "should not be initiated or continued for primary prevention of coronary heart disease". Dr Jeynes-Ellis of Wyeth Pharmaceuticals issued a postal circular to doctors on this study. Its message was not so stark. No surprise!
Women are rightly concerned about these issues and there is a need for independent expert fast-track advice to GPs who bear the brunt of patient anxiety generated by newspaper reports on therapeutic trials. Often GPs and physicians may be no better informed than patients because original journals or trial summaries in the medical press may arrive up to a week later. The Irish Medicines Board should organise an early warning response notice from an expert group when the results of a major clinical trial published in a reputable journal suggest that current conventional practice may be harmful. - Yours, etc.,
Dr BILL TORMEY,
Glasnevin Avenue,
Dublin 11.