Research to date has shown that tamoxifen can help to protect against osteoporosis. Although longer term research is needed to be sure just how effective that protection is, there is certainly no evidence that taking tamoxifen increases the risk of osteoporosis.

We tend to think of bone as something as solid and lifeless but actually there is a constant turnover of the bony tissue in our skeletons.  This is carried out by two types of cells: osteoblasts, which make new bone and osteoclasts, which break down old bone.

In the earlier part of our lives the osteoblasts are more active than the osteoclasts and the weight of bone in our bodies steadily increases up to the age of about 30. From then onwards the balance changes and we slowly start to lose some of our bone mass. This process is accelerated in women after the menopause. In about one third of women the loss of bone after the menopause is particularly rapid and this can lead to the problem of osteoporosis. 

Osteoporosis is loss of bone mass, leading to thinning of the bones which makes them more fragile and can lead to problems with bone pain and even fractures.

The reason why women lose bone more rapidly after the menopause is because they are no longer making the female hormone oestrogen. Taking HRT (hormone replacement therapy) containing oestrogen will greatly help reduce the chances of osteoporosis developing. Usually, however, HRT is not recommended for women who have had breast cancer.

Studies done during the early 1990s looked at the effect of tamoxifen on the bones. These reports showed that in women who were past the menopause and who were taking tamoxifen there was an actual, gradual, slight increase in their bone mass rather than a decrease. This increase was less than would have been seen if they had been taking oestrogen-based HRT but it was still an increase, rather than a decrease.

If you have a problem with osteoporosis then you should discuss the choices that are available for treatment with your doctor. These include a group of drugs called bisphosphonates which have also been shown to reverse osteoporosis in many people.