In September this year a group of international breast oncologists met in Oxford to update what has become known as the Oxford Overview. Known as the 'Early Breast Cancer Trialists Group,' this meeting began a number of years ago to try to more clearly answer some of the treatment questions in early breast cancer through international collaboration. Since its inception, the members of this group have continued to meet.
Most of our treatment recommendations come from large Phase III clinical studies which compare two or more treatments in a group of similar patients to determine which therapy is better. Most trials include a large number of women - many of the recent hormone trials had 8000 or more women. Other trials are smaller but these days a small Phase III study has close to 1000 subjects.
Even with these large numbers, some questions cannot be answered clearly as breast cancer is a confusing disease with many subtypes and patterns of behaviour. One way to try to sort out these questions is to pool the data together. Putting a large number of clinical trials together that looks at a similar group of patients and asks a similar question is called a 'meta analysis'. The benefit of doing meta analysis is that it can give more statistical power and strengthen a result by increasing the number of subjects (30,000+) and the number of events such as recurrences. The problem with a meta analysis is that often studies pooled together are not sufficiently the same to give an answer that one can trust. Thus, care must be taken to match the studies used.
The Oxford Overview group has become experts at meta analysis for breast cancer and have provided some of the strongest data to support our current treatments. Their analyses have long term follow up of many older trials which helps assess the long term benefits of treatment.
So what did the group find this year? The results have not yet been published but will be released soon. At this time, there are no surprises but confirmation that our guidelines are appropriate. There is a steady improvement in the survival rate in women with early breast cancer. The 2006 results show an improvement compared to the last analysis 5 years ago.
Chemotherapy is effective for women with early breast cancer in particular estrogen receptor negative diseases although all types of invasive cancer show a benefit. Of interest, the meta analysis confirmed that the addition of taxanes to the adjuvant recipes does add benefit for node positive women overall and probably for high risk node negative women. There is further analysis going on to see if all women with these features should have a taxane or if less aggressive tumours can be spared the side effects. More research in specific clinical trials is needed to answer this question.
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Hormone therapy for estrogen receptor positive disease is effective including removing the ovaries for women who are premenopausal. We still need to answer if ovarian removal helps after chemotherapy or is necessary if tamoxifen is given but certainly on its own it is effective although less so for high risk women than chemotherapy. And the group looked at the effects of treatment by age and found a benefit for both pre and postmenopausal women.
Single clinical trials provide the first evidence for treatment effects. Meta analyses may add to the strength of these findings. The real impact however is when one assesses how a community or population does. In British Columbia, due to our cancer system (BC Cancer Agency) and the data we collect, we are able to chart the effect that our treatment recommendations have on outcomes of the population and how this compares to the Oxford Overview.
We have published reports in both early and recurrent breast cancer that has confirmed what the meta analyses have shown. By adopting new and proven treatments on a province wide basis, we have been able to see better survival for women with breast cancer in BC. It is gratifying to be able to see that outcomes match those reported and persons in a clinical trial are not different compared to women in BC.
Are we making progress? Yes! Once again the findings from the Oxford group show a steady survival improvement. These are not giant leaps but steady forward steps towards curing more women of this disease.
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