Study confirms previous findings on HRT and breast cancer type
A US study has found more evidence of a link between hormone replacement therapy (HRT) and breast cancer, in line with previous research.
Researchers found that postmenopausal women who take combined oestrogen/progestin HRT for three years or more are more likely to develop a form of breast cancer called lobular breast cancer, which affects the chambers containing milk-producing glands, as well as being at increased risk of the more common form of breast cancer - ductal breast cancer.
Lobular breast cancer accounts for about 15 per cent of cases. It is usually hormone-sensitive - hence easier to treat - but is harder to spot by breast screening.
Cancer Research UK said that the findings agree with previous research on the effect of HRT on breast cancer risk.
Henry Scowcroft, the charity's senior information officer, said: "HRT can be a huge help in alleviating the symptoms of the menopause, which can be very uncomfortable on a day-to-day basis. These advantages need to be considered alongside any potential increase in breast cancer risk, which varies from woman to woman.
"If you are worried about HRT the best thing to do is to discuss the matter with your GP, who will be able to help you weigh up your options," he added.
The study, which was carried out by the Fred Hutchinson Cancer Research Centre in Seattle, analysed HRT use in more than 1,500 postmenopausal women, including 1,044 with breast cancer and 469 controls.
Of those patients with breast cancer, 324 cases were lobular; 524 cases were ductal, which arises in the ducts that carry milk to the nipple; and 196 cases were mixed ductal-lobular.
The researchers took into account the recency and length of HRT usage as well as the type of tumour and found that current users of combined HRT had a 2.7-fold elevated risk of lobular cancer and a 3.3-fold risk of ductal-lobular cancer.
The risk of lobular cancer was only raised in women who had used HRT for three or more years.
The study authors noted that while ductal cancer has increased in incidence by just three per cent between 1987 and 1999 in the US, the number of cases of invasive lobular and ductal-lobular breast cancers rose by 52 per cent and 96 per cent respectively over the same timescale.
Dr Christopher Li, lead author of the study in Cancer Epidemiology journal, commented: "Our research suggests that the use of postmenopausal hormone-replacement therapy, specifically the use of combined oestrogen-plus-progestin preparations, may be contributing to this increase."
In a 2006 paper in the Lancet, the Million Women Study, funded in part by Cancer Research UK, revealed that women taking HRT were more at risk of lobular breast cancer than the ductal form.