A new study shows that a specific formulation of hormone replacement therapy increases the risk of lobular breast cancer.

There are several different kinds of breast cancer. The type known as lobular breast cancer has been on the increase in recent years but, fortunately, it is less aggressive than another form known as ductal breast cancer.

Now researchers at the Fred Hutchinson Cancer Research Centre in Seattle report on a multicenter study that reveals a link between the progestin component of hormone replacement therapy and lobular breast cancer. Women taking a combination of progestin and estrogen for up to five years were 1.6 times more likely to develop the condition compared to those who had never used HRT. If they were on the hormones for more than five years, the risk was twice that for non-HRT users. If the women took the dose regime that involves continuous progestin for 25 days a month the risk was even higher, at 2.5 times. But estrogen alone was not linked to any increase in breast cancer risk. Indeed, there was a suggestion that risk might even be slightly reduced. These new findings add to the mountain of evidence on HRT and future health - all of which has to be taken into account when a woman decides whether to take hormone replacement. Clearly this has to be an individual decision, with a woman weighing up the pros and cons very carefully with her doctor.

Source

Cancer 15th December 2002 (on-line version 3rd December)