More intensive treatment of DCIS reduces the risk of invasive breast cancer – . Health Blog

Breast cancer screening with mammograms or other tools (like MRI) has increased the rates of diagnosis of very early breast cancers known as DCIS (ductal carcinoma in situ). Unlike invasive breast cancers, DCIS cancers are localized and have not spread to deeper tissues or anywhere else in the body. Given the increased rates of diagnosis, there has been significant controversy over the real risks of DCIS and the best treatments. Some suggest that women are over-treated for a condition that does not significantly increase the risk of long-term death, and others advocate more intensive preventive treatment in women with DCIS.

Long-term results for women with and without DCIS have so far been limited

A study recently published in the BMJ offers the best data on the risks associated with DCIS and the effects of various treatments. In the study, more than 35,000 women diagnosed with DCIS by mammography were followed for up to 20 years to see if they developed invasive breast cancer or died of breast cancer.

Overall, the researchers found that DCIS more than doubled the risk of developing invasive breast cancer and increased the risk of dying from breast cancer by 70% compared to the general population. In addition, the researchers observed that more intensive treatment for DCIS was associated with a lower risk of invasive breast cancer. Compared to women who had both breast-conserving surgery (lumpectomy) and radiation therapy, those who had a lumpectomy alone had a 43% higher rate of breast cancer and those who had a mastectomy had a 45% lower rate of breast cancer. A larger DCIS-free margin in the biopsy sample was also associated with lower rates of invasive breast cancer development. In women with estrogen receptor positive DCIS, hormone treatment to lower estrogen levels was associated with a lower risk of invasive breast cancer.

The results of this new study are largely similar to a US study of more than 100,000 women with DCIS that found women with DCIS to be 80% more likely to have breast cancer than the general population, although this study failed to determine how that DCIS was diagnosed. A Danish study also found that women with DCIS treated with mastectomy had a lower rate of invasive breast cancer in that breast than women treated with more conservative surgery with or without radiation therapy.

What does the new research mean for a woman diagnosed with DCIS?

This study showed that increased risk of cancer persisted for more than 15 years after DCIS was diagnosed, and that more intensive therapy than lumpectomy alone – whether with mastectomy, radiation therapy, or endocrine therapy – reduced the risk of invasive breast cancer in women with DCIS. The lowest risk of invasive breast cancer was in women who had chosen to have a mastectomy.

The risk of invasive breast cancer was seen regardless of the severity of the DCIS. Women with low- or moderate DCIS and high-grade DCIS were at increased risk in the long term.

Women recently diagnosed with DCIS should work with their treatment team to consider the best individual treatment strategies based on their preferences and other health conditions. This new study confirms the need to consider the long-term consequences of DCIS in treatment decisions and may prompt doctors and patients to consider more intensive treatments to reduce the risk of invasive breast cancer and the risk of dying from breast cancer . Although this study did not provide details of surveillance strategies such as regular mammograms or other exams, based on these results, patients with DCIS should continue active breast cancer surveillance decades after their diagnosis.