Chemotherapy causes bone loss

Chemotherapy can have severe side effects

Drug treatment for breast cancer causes a faster loss of bone density than previously thought.

The loss in strength of the bone puts women at risk of osteoporosis.

Tests were carried out on 35 pre-menopausal women with an average age of 42 by scientists at Ohio State University in the US.

They were surprised to find that some of the women lost 8% of their bone density after undergoing 12 months of chemotherapy treatment.

The bone density loss was so significant that the tests were stopped to allow the women to seek treatment.

Surprising result

Researcher Dr Charles Shapiro said: "We were surprised that (bone loss) occurred so early because other studies had begun to evaluate patients at 12 months after chemotherapy commenced.

"An independent committee met, and they concluded that these 35 women have lost so much bone, 8 percent, in the spine that it was unethical in view of that to treat them with placebo."

Patients with cancer are surviving longer than ever before, so research into the long-term side-effects of cancer therapy is increasingly important

Dr Mary Berrington

Chemotherapy causes loss of bone density because it causes a woman's ovaries to shut down prematurely, stopping production of the female hormone oestrogen.

Oestrogen plays a vital role in protecting the bones from deterioration.

Women naturally stop producing oestrogen when menopause begins, but the decline in the hormone, and resulting drop in bone density, occurs at a faster rate when chemotherapy is administered.

Post-menopausal women average a decline of about 1% to 2% in bone mineral density per year.

Nasal spray

Researchers had later planned to test the effects of a nasal spray on slowing bone loss - four patients would receive the spray and three a placebo, or dummy medication.

But it was decided that the risk of osteoporosis was too great to justify offering some of the women no treatment at all.

Dr Shapiro said: "We focus on the side-effects of chemotherapy, but we don't focus as much as we should on early menopause leading to rapid bone loss.

"The results of this study support a role for bone density scans in those women who develop chemotherapy induced ovarian failure."

Dr Mary Berrington, Science Information Manager for the Cancer Research Campaign, told BBC News Online: "This is an important area of research - with modern treatments patients with cancer are surviving longer than ever before, so research into the long-term side-effects of cancer therapy is increasingly important.

"It's been known for some time that chemotherapy can lead to a reduction in bone density in women.

"More studies are needed to assess the extent of this loss in premenopausal women, and on how this affects their risk of osteoporosis.

"There is also a need for well designed intervention trials to find the best way of preventing or slowing the loss of bone density."

Osteoporosis can be slowed with a balanced diet rich in calcium and vitamin D, exercise and tests to measure bone density.

The research is published in the Journal of Clinical Oncology.