Switching to anastrozole after 2–3 years' treatment with tamoxifen not only helps women to live longer but it also increases their chances of remaining cancer free after initial treatment of breast cancer, claim researches in the online edition of The Lancet Oncology.
"A lot of people have been waiting to see whether aromatase inhibitors will show a survival advantage, and I think these data will assure them that 5 years of tamoxifen is no longer the standard of care; the best treatment for women with hormone-sensitive early-stage breast cancer should include an aromatase inhibitor", concludes lead author Professor Walter Jonat (University of Kiel, Kiel, Germany).
Several studies have now been done to investigate whether switching to an aromatase inhibitor after an initial period of tamoxifen is beneficial for postmenopausal women with early-stage breast cancer, but to date, none of these have shown an improvement in patients' overall survival. Professor Jonat and colleagues therefore decided to combine all the data from the only three trials to compare the outcomes for postmenopausal women with hormone-sensitive early-stage breast cancer who either remained on tamoxifen for the full 5-year treatment period, or switched to a type of drug called a non-steroidal aromatase inhibitor after 2–3 years' treatment with tamoxifen. All the trials investigated the aromatase inhibitor anastrozole.
"We showed that the benefits of switching to anastrozole in terms of disease and recurrence-free survival that have been seen in the individual trials translate into a significant benefit in overall survival", explains Professor Jonat.
The Arimidex group had a 29% lower risk of death.
The Arimidex group had a 41% higher chance of disease-free survival.
The Arimidex group had a 45% lower chance of cancer relapse in any part of the body.
"We used a technique called meta-analysis to analyse the data because it increases the power and precision of the analysis, helps to avoid bias or random error, and can therefore address questions that cannot be answered from the individual trials", he continues.
Despite this powerful technique, Professor Jonat concedes that many questions remain unanswered in the field of breast cancer treatment. Future research will need to address what the best duration of treatment is, whether tamoxifen or aromatase inhibitors should be given first, and whether any combinations of other drugs might improve further on these results.
