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A major study of women with ductal carcinoma in situ (DCIS), a breast condition that can turn into invasive cancer, has shown that surgery to remove tissue followed by radiation therapy offers better protection compared to surgery alone.
The study, presented at the 12thEuropean Breast Cancer Conference, followed patients for up to 27 years. Although it shows that the benefit of radiation therapy and surgery over surgery alone persists, it also suggests that this benefit diminishes over time.
The researchers say 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.
DCIS is a condition in which the cells that line the milk ducts have started to turn into cancer cells, but have not spread to other parts of the breast. DCIS is often detected by breast exams and affects tens of thousands of women in Europe each year.
Only a proportion of DCIS cases will progress to invasive cancer, and little is known about which cases will progress, so the treatments available to patients are very similar to treatments for invasive breast cancer.
The research was presented by Dr. Maartje van Seijen from the Netherlands Cancer Institute (Amsterdam, The Netherlands). She said: “Most women who are diagnosed with DCIS are offered surgery to remove abnormal breast tissue and are often offered radiation therapy as well, although most would not develop invasive breast cancer. We wanted to see how this group of women progress in the long term, based on the treatment they received. “
The study included 10,045 women diagnosed with DCIS in the Netherlands between 1989 and 2004. The researchers collected data on whether the women were treated with breast-conserving surgery to remove DCIS, or breast-conserving surgery followed by radiation therapy or mastectomy (excision chest).
They collected information on whether the women were later diagnosed with DCIS in the same breast again or with invasive breast cancer in the same breast.
In the first ten years after diagnosis, women who underwent breast-conserving surgery but not radiation therapy had a 13.0% risk (130 out of 1000 women) of being re-diagnosed with DCIS and their risk of Invasive breast cancer was 13.9% (139 out of 1000 women). of 1000). Women treated with breast-conserving surgery and radiation therapy had a 4.6% (46 of 1000 women) risk of DCIS in the first ten years and 5.2% (52 of 1000 women) of invasive breast cancer.
But while women who received radiation therapy had lower risks in the first 10 years, in subsequent years (10 or more years after diagnosis), their risks were closer to those of women who only had surgery. Ten years after diagnosis, women who underwent breast-conserving surgery but not radiation therapy had a 1.2% risk (12 out of 1000 women) of being re-diagnosed with DCIS and their risk of cancer invasive breast was 11.8% (118 out of 1000).
In women treated with breast-conserving surgery and radiation therapy, these figures were 2.8% (28 out of 1000 women) for DCIS and 13.2% (132 out of 1000 women) for invasive breast cancer.
The risk of recurrence of DCIS or invasive cancer in these women will decrease over time, whether they have undergone breast-preserving surgery alone or breast-preserving surgery with radiation therapy. This study shows that, in general, the addition of radiation therapy gives women the best opportunities. However, there is the possibility that a new DCIS or invasive cancer will develop that is unrelated 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, radiation therapy itself could cause new breast cancer, often many years after radiation therapy was given. “
Dr. Maartje van Seijen, Netherlands Cancer Institute
The study also showed that women who had a mastectomy to treat their DCIS had the lowest risk of invasive cancer. Dr. van Seijen added, “Although patients who have a mastectomy have the lowest risk of recurrence, it is important to remember that, based on previous research, overall survival in patients who have a mastectomy is the same as in patients receiving less aggressive treatments. For most women with DCIS, whose condition will never become invasive, mastectomy would be considered overtreatment. “
Professor Emiel Rutgers is President of the European Breast Cancer Council, a member of thethScientific Committee of the European Breast Cancer Conference and did not participate in the research.
She said: “DCIS is a condition that affects thousands of women and a proportion of them go on to develop invasive breast cancer. Most of these women will have decades to live, so it is vital that we understand the long-term impact. term of the treatments we offer.
“We still need to know much more about DCIS and, in particular, which women will develop invasive cancer and which will not. In the meantime, studies like this give patients and their doctors more information about the benefits and costs of the different treatments available to them.
“Previous research shows that the risk of dying from cancer is only 1-2% in the 20 years after a diagnosis of DCIS. Therefore, it is important to remember that, whether it is treated with breast-conserving surgery alone or surgery With radiation therapy, the risk of dying from breast cancer in women who had DCIS remains very low. “
Source:
European Organization for Cancer Research and Treatment
