London - Women with breast cancer were offered new hope this week by research hailed as the biggest advance in treatment for the disease for 30 years.
The findings announced in America, mark a watershed in breast cancer care and are expected to topple the most commonly prescribed drug for the disease, tamoxifen, from its perch.
Tamoxifen has been the gold standard in breast cancer since the 1970s and saved millions of lives by reducing the recurrence of cancer following surgery by 50 percent.
But research findings announced at the San Antonio Breast Cancer Symposium in Texas on Thursday, and published online in the Lancet, show the first of a new class of drugs called aromatase inhibitors can cut the rate of recurrence by 76 percent, half as much again as achieved by tamoxifen, and has fewer side effects.
The results of the five-year trial involving 9 300 women, the largest conducted for breast cancer, show that women taking the aromatase inhibitor anastrazole (brand name Arimidex) were less likely to have their cancer spread and lived longer.
The absence of serious side effects is crucial because hopes have been raised in the past for new treatments that appeared effective only to be dashed when serious problems emerged after long-term use.
Results from earlier trials have shown the benefits of aromatase inhibitors over tamoxifen but until now doctors have cautioned against using them as a first line treatment for the disease until long-term findings were in.
On Thursday, researchers said the latest findings from the ATAC study (Arimidex, Tamoxifen, Alone or in Combination) heralded a new dawn in breast cancer treatment.
The drugs are only suitable for women who have gone through the menopause and have hormone sensitive cancer, 80 percent of all cases.
Professor Tony Howell, of the Christie Hospital, Manchester, who led the international study, said:
"We have seen this result coming for several years. The important thing is that we have now got five-year data and there is no new toxicity (associated with anastrazole). Fewer patients relapse and it is better tolerated. That is why we are saying it should be the treatment of choice."
Professor Jack Cuzick, Cancer Research UK head of epidemiology at the Wolfson Institute, London, said:
"We are very excited by these results. For post-menopausal women in the UK who have breast cancer, and there are more than 100 000 of them, these data represent long-awaited evidence of a treatment option that will be more effective in preventing their cancer returning while minimising the risk of side effects."
Tamoxifen causes an increased risk of blood clots, stroke and cancer of the womb lining, which is reduced with anastrazole.
Five times as many women on tamoxifen have hysterectomies because of concern about changes to the endometrium compared with those on anastrazole.
A potentially serious side effect of aromatase inhibitors is their effect on the bones with an increased risk of fractures.
But a second research paper presented at the San Antonio conference on Thursday by an Austrian group led by Michael Genant showed that giving anastrazole in combination with a biphosphanate, a drug to prevent bone loss, cut the fracture rate.
Anne Donald, 56, from Nuneaton, England was started on anastrazole in October following a mastectomy and chemotherapy.
Her doctors recommended it because of the lower risk of side effects on her womb.
"I was keen to avoid anything that might make worse what already looked like a weak area. I knew one side effect of tamoxifen was difficulties with the uterus," she said.
The only problem she has experienced so far was a slight stiffness in the joints, she said.
"I am very comfortable and very pleased to be on Arimidex. I had heard of tamoxifen but I hadn't realised the two drugs were in competition."