Ductal Carcinoma in Situ (DCIS)

Ductal carcinoma in situ (DCIS) is NOT invasive breast cancer

Ductal carcinoma in situ (DCIS) is actually the most common type of non-invasive breast cancer. Ductal means that cells change inside the milk ducts,carcinoma refers to any cancer that begins in the skin or other tissues(including breast tissue), and in situ means “in its original place.” DCIS is called “non-invasive” because it hasn’t actually spread beyond the milk duct into any healthy surrounding breast tissue. The cancer cells are only in the lining of the breast duct.

DCIS is not in and of itself life-threatening but…

Having DCIS can increase the risk of developing an invasive breast cancer later on which can be life-threatening. When you have had DCIS, you are at a higher risk for invasive breast cancer later on or for developing a new breast cancer than a person who has never had breast cancer before. Normally, recurrences happen within 5 to 10 years after initial diagnosis. The chances of a recurrence are under 30%.

DCIS may be over treated

A study was released in 2015 suggesting that patients who receive a diagnosis of DCIS may be receiving over-treatment. The observational study followed a group of over 100,000 women over 20 years and showed that regardless of treatment type (lumpectomy or mastectomy), those treated for DCIS had approximately the same chance of dying from breast cancer as the average woman does. The data did, however, show that younger women under the age of 40 with DCIS are at a higher risk. The main points from the research, as summarized in the paper in JAMA Oncology:

  1. The purpose of this study was to estimate the mortality from breast cancer following a diagnosis of ductal carcinoma in situ (DCIS) and to identify risk factors for death from breast cancer.
  2. The 20-year breast cancer–specific mortality rate following a diagnosis of DCIS was 3.3%.
  3. Young age at diagnosis and black ethnicity were significant predictors of breast cancer mortality.
  4. Prevention of invasive in-breast recurrence with either radiotherapy or mastectomy did not prevent death from breast cancer.
  5. The clinical course of women with DCIS is similar to that of women with small invasive breast cancers.

If you or someone you know has been diagnosed with DCIS, it is important to discuss these findings with your medical team and make sure you understand what the research means for your course of treatment.

DCIS testing has come a long way

As Rethinkers we love the idea of precision medicine! The Oncotype DX DCIS test is a genomic test that can help you make the right choices about treatments post surgery for DCIS. The Oncotype DX DCIS test analyzes the activity of a group of genes that can help doctors figure out a woman’s risk of DCIS coming back and/or the risk of a new invasive cancer developing in the same breast, as well as how likely she is to benefit from radiation therapy after lumpectomy.

The test results assign a Recurrence Score — a number between 0 and 100 — to the DCIS.

The idea is that you and your healthcare team consider the Recurrence Score in combination with other factors, such as the size and grade of the DCIS, whether or not the DCIS is hormone-receptor-positive, and your age. Together you can make a choice about whether or not you should have more treatment like radiation or chemo.

DCIS needs more research to alleviate unnecessary trauma

Even though DCIS is a different disease then invasive breast cancer, it is often treated in the same way which can cause lingering side-effects both physical and emotional that continue well after treatment ends. More research is needed to help practitioners communicate more effectively with patients about DCIS, their risks with associated treatment and follow-up to ensure that they are coping with whatever choices they make.

Further research can also identify thresholds for clinical intervention for DCIS that could be used to determine if and when to cease active surveillance and commence treatment, rather than treating young patients swiftly and aggressively when it may not be necessary.

Right now, the Duchess Study is running in Canada to evaluate whether the use of the DCIS score changes the treatment recommended and the treatment received in women with low to moderate risk DCIS following breast conserving surgery who are candidates for radiation therapy.

For more information about breast cancer, click here.

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