The current state of knowledge might be summarised as follows:
- Evidence is strongly in favour of switching to an aromatase inhibitor after two to three years of tamoxifen.
- The ATAC subgroup evidence suggests that women whose breast cancers are ER+/ PR- might benefit from having treatment with an aromatase inhibitor straight away rather than starting on tamoxifen. However, others support giving patients with low ER cancers an aromatase inhibitor rather than tamoxifen.
- It might be preferable to start with an aromatase inhibitor for women whose breast cancers are HER 2 positive.
- There is uncertainty about whether it is preferable to start with an aromatase inhibitor for newly presenting patients. There are cost implications and consequences for bone health if this were to become routine practice.
- The optimal duration of treatment using aromatase inhibitors in the adjuvant setting is unclear. Also, long-term toxicities are not yet known.
Treatment decisions
There are many issues to consider when planning a woman’s adjuvant treatment for breast cancer. With hormonal therapy, each woman needs to discuss her own situation with her specialist and a decision should be reached based on current knowledge and the woman's individual situation. Currently, grade, stage and nodal status all need to be considered, as well as hormone receptor status. These factors will continue to be significant when making decisions regarding treatment.
For some women, particularly those with small screen-detected cancer, the risk of recurrence is so low that tamoxifen may remain the treatment of choice. However, where the risk of recurrence is higher the clinical consensus is that an aromatase inhibitor should be made available to patients at some point during therapy on a routine basis.
With regard to the effect of aromatase inhibitors on bone mineral density, bisphosphonates may be helpful but there is insufficient data to suggest they should be used as standard. If women are not routinely offered a bone mineral density scan before starting an aromatase inhibitor, this is something they could request from their specialist.
As always, the benefits and risks of treatment need to be weighed so that women will have the most appropriate treatment for their breast cancer with the aim of maintaining as long a disease free interval as possible.