For women at high risk of developing breast cancer, it could hardly have been better news. A US study to find out if the drug tamoxifen could be used to prevent the disease developing had proved to be so successful that its sponsors were stopping in mid-stream to announce the dramatic findings.
"This is the first time in history that we have evidence that breast cancer can not only be treated but can also be prevented," Dr Bernard Fisher, scientific director of the study, told a news conference. But the medical establishment in Britain, where tamoxifen was first used to treat advanced breast cancer in the 1970s, was less than breathless with excitement.
Doctors there criticised the US researchers for interrupting the study before its completion and before the implications of long-term use of the drug had been fully examined. Irish cancer specialists, however, have no doubt that the US announcement is significant.
Doctors here agree that more research must be done, but say there is already a substantial body of information about the long-term and side effects of tamoxifen because of its use for nearly 30 years as a breast-cancer treatment.
In the US trial of more than 13,000 healthy women, there were 85 cases of invasive breast cancer among the more than 6,600 who were on tamoxifen, as opposed to 154 cases in the equal number of women who were given dummy pills.
Those figures would suggest the drug can reduce breast-cancer cases by 45 per cent. The project, which began in 1992, was sponsored by the US National Cancer Institute and concentrated on women considered to be at high risk of developing the disease.
Dr Des Carney, consultant medical oncologist at the Mater Hospital in Dublin, said a difficulty with the study was the small numbers involved, but he believed the findings were "a very big step forward". He suggested its use here, if targeted properly, could have the same effect as a national breast cancer screening programme.
Dr David Fennelly, a breast-cancer specialist at St Vincent's Hospital in Dublin, said the British were "perhaps being a little overcautious." He said the studies had shown not only that tamoxifen could be effective in preventing breast cancer, but also that it could be used to treat certain types of the disease - more prevalent in younger people - which were previously thought not to be responsive to the drug.
Tamoxifen counteracts the oestrogen in a woman's body that encourages the tumour to grow, but is in itself a carcinogen, trebling the risk, normally very low, of a woman developing uterine cancer.
Dr Fennelly said the US scientists would have taken these factors into account when deciding to release their findings early. "Uterine cancer develops in only a very small percentage of cases. It's a question of weighing up the risks, and this is something that's done every day in doctors' clinics in Ireland".
Dr Carney, who is also chairman of the Irish Cancer Society, said the risk of developing uterine cancer from taking tamoxifen was negligible. In addition, it was not an aggressive cancer and was usually diagnosed early and successfully treated. The question many women will ask as a result of this week's news is what should they do about it. Is it advisable to ask their doctor to start prescribing tamoxifen immediately? Dr Fennelly said any woman who believes she is in a high-risk category and that the drug might be beneficial should consult her GP with a view to being referred to a specialist. Women most obviously at risk are those with a strong family history of the disease.
There is no question of tamoxifen being given to every woman who wants it, Dr Carney stressed. But he said family history, combined with a genetic test and the taking of a blood sample, could identify women with a 50 per cent-plus risk of developing breast cancer.
"We're talking here about 1,500 people a year in Ireland getting breast cancer. Between 50 and 75 of these would be genetic or familial. Preventing those would be the same in effect as having a national breast-cancer screening programme. At the moment we can say to women `You have a high risk of getting breast cancer, but there's nothing we can do to stop it'."
Before tamoxifen can be made widely available for cancer prevention, the extension of its use will have to be approved by the Irish Medicines Board. Its chief executive, Dr John Kelly, said such applications were fully reviewed and decisions based "on an analysis of the benefits and risks".
The process of making an application, which must include the available clinical research, and having it approved can take several months. But there is nothing to stop doctors prescribing it in individual cases in the meantime.
Concern that commercial considerations might be behind this week's development - the patent for tamoxifen has expired everywhere except in the US - were dismissed by the Irish doctors.
In any event, whatever the merits of this week's headline-grabbing announcement, it's clear that research is making inroads into tackling a disease which one in 13 Irish women will develop.
A small percentage of men, one for every 100 women, also get breast cancer, but for women it is the biggest cause of cancer deaths in Ireland. This week science moved a step closer to ensuring that such statistics will make less grim reading in future.