By Caroline Parkinson
Health reporter, BBC News, Barcelona
Drug treatment which stops a woman's periods may protect against the effects of chemotherapy, a study suggests.
Chemotherapy works by targeting fast-dividing tumour cells.
However, reproductive system cells, which also divide rapidly, can be damaged, potentially compromising the patient's fertility.
A European fertility conference heard Egyptian researchers had used a drug to stop rapid reproductive cell division, and take them out of the firing line.
The team, from Benha University in Mansoura, used a drug called GnRHa to shut down the process of egg release and periods, effectively creating a "temporary menopause".
The drug works by blocking the natural messaging system which directs ovulation and menstruation.
This research looked at 80 breast cancer patients. Half were given the drug treatment with their chemo, while the others were not.
They were they then followed up three to eight months after their cancer treatment was completed.
In the drug treatment group, 90% of women saw their periods restart, and 69% were ovulating again.
In comparison, only a third of the chemo-only group had their periods restart and 25% were ovulating.
UK expert Professor Peter Braude said this study did show significant benefits, where previous work had shown minor ones, but stressed longer term studies were required to confirm the stronger effect.
A second study also presented to the European Society of Reproduction and Embryology in Barcelona focused on speeding up the process of harvesting eggs from women who are about to undergo cancer treatment, for possible use once their treatment is completed.
Currently the stimulation of ovaries to produce eggs has to be done at the start of a woman's menstrual cycle.
Depending on when she is diagnosed with cancer, a woman may have to wait six weeks before her eggs can be collected - time she may not have if her treatment is urgent.
A team led by Professor Michael von Wolff at the University of Heidelberg showed that ovaries can be stimulated during the final phase of the menstrual cycle.
This potentially increases the chance that a cancer patient could receive fertility-protecting treatment even if she urgently needs chemotherapy.
In a pilot study mature eggs were obtained before cancer therapy within two weeks.
Professor von Wolff said: "Two weeks is an acceptable amount of time in many diseases to wait before starting a cancer treatment such as chemotherapy, but three to six weeks is far too long."