US researchers have shown scalp-cooling caps prevented hair loss in 50 per cent of breast cancer patients undergoing chemotherapy.

Hair loss is a dreaded side-effect of chemotherapy, a constant visible reminder of the cancer threatening a patient's life.

Across Europe and the UK scalp cooling technology is widely used by women with breast cancer to help them keep their hair.

In Australia, women have been petitioning for more of the costly devices to be introduced.

Two clinical trials conducted in the US showing they work may now help the practice gain ground in Australia.

The trials, published in JAMA, examined the hair loss among women with breast cancer who received scalp cooling before, during and after chemotherapy.

In one study, researchers at the College of Medicine, Houston, randomly assigned 182 women with breast cancer undergoing chemotherapy to scalp cooling.

Of the patients who received scalp cooling, half retained their hair.

They were also significantly more likely than patients who did not receive scalp cooling to have less than 50 per cent hair loss.

The second study was conducted at the University of California and showed similar results.

Hair loss of 50 per cent or less was seen in 67 of 101 patients from the scalp cooling group.

Nearly a third also reported feeling less physically attractive compared to the 56 per cent of patients in the control group.

Only a small number, 3.8 per cent, experienced the adverse event of mild headache.

While very positive results, all authors said more research was needed.

"Further research is needed to assess longer-term efficacy and adverse effects," the authors of the first study wrote.

It's thought scalp cooling reduces the blood flow to hair follicles and reduces uptake of chemotherapeutic agents.

A cap is placed on the patient prior to chemotherapy, with temperatures on the scalp dropping between minus 3 to 5 degrees which can sometimes cause headache.

Last year, Australian woman Jodie McRae raised more than $70,000 through her not-for-profit organisation Jodie's Inspiration to buy two scalp-cooling caps machines for St Vincent's Hospital in Lismore in northern NSW.

Cabrini Hospital at Brighton in Victoria was the first in Australia to trial the machine in 2014 and now offers the free service for patients undergoing chemotherapy.