Medicine Matters oncology

So our study looked at anastrozole and tamoxifen for women who have hormone receptor positive ductal carcinoma in situ. And we compared these to treatments in relation to breast cancer recurrences. So overall, our data really showed that there is no difference in reducing recurrences between anastrozole and tamoxifen. However, I think for the patients and the clinicians discussing these treatments with the patients who have DCIS, it's important to really evaluate the different side effect profiles of these two drugs because women who already have a history of clotting or a deep vein thrombosis for example, tamoxifen is not indicated, and anastrozole will be better.

On contrast, women who have osteoporosis and DCIS, anastrozole would not be indicated. So tamoxifen is really the better choice. However overall, many women who have hormone receptor positive ductal carcinoma in situ, they most probably will just receive radiotherapy.

So we really need to identify women who are at increased risk of developing an invasive recurrence so that these women particularly can be treated with additional adjuvant therapy, for example either hormonal therapy or even chemotherapy if needed.

The NSABP B-35 trial obviously was very, very similar in terms of study design. Both trials involved postmenopausal women with hormone receptor positive DCIS, evaluating the same treatments. What is intriguing with the B-35 data is that they really only seeing this difference between anastrozole and tamoxifen in the late follow up period, so not actually during the active treatment period during the five years but only late.

So this is one of the reasons why we also looked into these different time periods in our analysis and we actually could not confirm a beneficial effect of anastrozole in a post five years after diagnosis.

So I think one of the reasons for that is that the definition of the endpoint. So we looked at breast cancer recurrences which included local recurrences and contrast recurrences either invasive or DCIS, whereas the B-35 trial also included distant recurrences. So I can only explain it probably with the different end point definition and that anastrozole might have a beneficial effect on this recurrences.

So we are planning to do an analysis looking specifically at distant recurrences. And we are currently collecting data from a registry, cancer registry, so that we can get all the information on distant recurrences and then also do an analysis to see whether we can see this same effect not necessarily just in the late follow up period, but to see whether we observe this significant difference for distant recurrences as well.