European Breast Cancer Conference, Vienna, March 2012
15-year follow-up on radiotherapy treatment after surgery for ductal carcinoma in situ
Dr Mila Donker – Netherlands Cancer Institute, Amsterdam
In total more than 1,000 patients in 34 centres in Europe were recruited and they were randomised between no further treatment of the breast, so only the excision of the lesion and no further local treatment of the breast, or radiotherapy of 50 Grays to the whole breast. We finished collecting the results in April of last year, this has resulted in a follow-up of almost 16 years.
One of the most important outcomes of the trial was local recurrence, so if the cancer comes back in the same breast. What you see here in the blue line is the patients that were randomised to the adjuvant treatment with radiotherapy, so after excision, the breast was irradiated. You see that after 15 years 82% of the patients did not experience a local recurrence. On the contrary, the patients who did not receive radiotherapy, almost 70% were without a recurrence. So that means that when the breast was not irradiated more than 30% of the patients had a local recurrence in the same breast.
When we split this figure in the DCIS recurrence or the more aggressive invasive recurrence, we see that for both recurrences radiotherapy reduced the local recurrence by almost 50%. But the most important outcome of the trial is the overall survival and the time to distant metastases because the time to distant metastases is what patients die from. A little bit surprisingly, but we see this in other trials as well, the reduction in local recurrence after the irradiation does not translate into a difference in overall survival or time to distant metastases. Both in the irradiated and not irradiated group, almost 90% were still alive after 15 years and 92% of the patients did not experience distant metastases in both groups. However, if we are looking at the patients that experience a local recurrence, so we take a little sub-group, if we’re looking at the patients with a DCIS recurrence, we see that the breast cancer related mortality, so the patients that die because of the breast cancer, we see no difference when patients experience a DCIS recurrence. They have the same breast cancer survival as patients who do not have a recurrence at all. However, if we’re looking at the patients who experience an invasive recurrence, we see that the breast cancer related mortality is almost 18 times higher than patients who do not have a recurrence or a DCIS recurrence. So this underlines the need for preventing a local recurrence.
So we come to our conclusions – without adjuvant radiotherapy to the breast, almost one out of three women will experience a local recurrence and half of these recurrences are invasive. Adjuvant radiotherapy reduces this risk by a factor 2. And at 15 years follow-up there are equal numbers in distant metastases and overall survival between the groups who were or who were not irradiated. However, if we’re looking at the survival after a recurrence, we see that the mortality after an invasive recurrence is five times higher and the breast cancer specific mortality after an invasive recurrence is even 17 times higher.