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Long-Term Evaluation of Treatment Efficacy After Primary DCIS Diagnosis


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A long-term study of women with ductal carcinoma in situ (DCIS) has shown that surgery to remove the tissue followed by radiotherapy may lower the risk of subsequent cancer compared to surgery alone. The study, presented at the 12th European Breast Cancer Conference by van Seijen et al (Abstract 14), followed patients for up to 27 years. Although it shows that the benefit of radiotherapy and surgery over surgery alone persists, it also suggests that this benefit decreases over time.

Researchers said these new findings clarify the long-term risks for women with DCIS and may help women and their doctors decide which treatment is right for them. The research was presented by Maartje van Seijen, PhD, of the Netherlands Cancer Institute. 

Dr. van Seijen commented in a statement: “Most women who are diagnosed with DCIS are offered surgery to remove the abnormal breast tissue, and they are often also offered radiotherapy, even though the majority would not go on to develop invasive breast cancer. We wanted to look at how this group of women get on in the long term according to which treatment they received.”

Maartje van Seijen, PhD

Maartje van Seijen, PhD

Study Methods

The study included 10,045 women diagnosed with DCIS in the Netherlands between 1989 and 2004. Researchers gathered data on whether the women were treated with breast-sparing surgery to remove the DCIS, breast-sparing surgery followed by radiotherapy, or mastectomy. They collected information on whether the women were subsequently diagnosed with DCIS in the same breast again or with an invasive breast cancer in the same breast.

Analysis Results

In the first 10 years after diagnosis, women who had breast-sparing surgery but not radiotherapy had a risk of 13.0% of being diagnosed with DCIS again, and their risk of invasive breast cancer was 13.9%. Women treated with breast-sparing surgery and radiotherapy had a risk of 4.6% of DCIS in the first 10 years, and a 5.2% risk of invasive breast cancer.

But although women who had radiotherapy had lower risks in the first 10 years, in the following years (10 or more years after diagnosis), their risks were closer to those for women who had surgery alone. After 10 years postdiagnosis, women who had breast-sparing surgery but not radiotherapy had a risk of 1.2% of being diagnosed with DCIS again, and their risk of invasive breast cancer was 11.8%. In women treated with breast-sparing surgery and radiotherapy, these figures were 2.8% for DCIS and 13.2% for invasive breast cancer.

Dr. van Seijen said, “The risk of DCIS or invasive cancer recurring in these women will diminish over time, whether they had just the breast-sparing surgery or breast-sparing surgery with radiotherapy. This study shows that, overall, the addition of radiotherapy gives women the best chances. However, there remains a chance of a new DCIS or invasive cancer developing that is not related to the initial diagnosis, and we would expect this risk to be similar between the two types of treatment. In a very small number of women, radiotherapy itself might cause a new breast cancer, often many years after the radiotherapy was given.”

The study also showed that women who had mastectomy to treat their DCIS had the lowest risks of invasive cancer. Dr. van Seijen added, “Although patients who have a mastectomy have the lowest risk of recurrence, it's important to remember that, according to previous research, overall survival in patients who have a mastectomy is the same as in patients who have less aggressive treatments. For the majority of women with DCIS, whose condition will never become invasive, mastectomy would be considered overtreatment.”

Disclosure: For full disclosures of the study authors, visit cm.eortc.org.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
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