DCIS is a Bona Fide Breast Cancer, Not a Cancer Precursor

MedicalResearch.com Interview with:

Steven Narod, MD, FRCPC, FRSC Senior Scientist, Women’s College Research Institute Director, Familial Breast Cancer Research Unit, Women's College Research Institute Professor, Dalla Lana School of Public Health, University of Toronto Professor, Department of Medicine Tier 1 Canada Research Chair in Breast Cancer University of Toronto

Dr. Narod

Steven Narod, MD, FRCPC, FRSC
Senior Scientist, Women’s College Research Institute
Director, Familial Breast Cancer Research Unit, Women’s College Research Institute
Professor, Dalla Lana School of Public Health, University of Toronto
Professor, Department of Medicine
Tier 1 Canada Research Chair in Breast Cancer
University of Toronto

MedicalResearch.com: What is the background for this study? What are the main findings? 

Response: In the past we have shown that about 3 percent of women with ductal carcinoma in situ (DCIS) will die of breast cancer within 20  years of diagnosis.   In the current study, we took a very close look at how the different treatments impact on the risk of dying of breast cancer.

Women with DCIS are at risk for  both a new cancer within the breast and dying of breast cancer from cells that spread beyond the breast (lung, liver, brain and bone).   About 20% of DCIS patients will get a new breast cancer within the breast at 20 years.

  • We show here that it is not necessary to develop a new cancer within the breast to die of breast cancer,  in some cases the DCIS spreads directly in the absence of local recurrence.
  • We show that radiotherapy can prevent 25% of the deaths from breast cancer after DCIS. And this has nothing to do with local recurrence.
  • We show that mastectomy reduces the chance of a getting a new cancer (local recurrence) but  doesn’t reduce the chance of dying of breast cancer.

So, if the goal is to prevent new cancers in the breast –   then mastectomy is the best treatment

If the goal is to prevent the woman from dying of breast cancer – then radiotherapy is the best treatment.  Continue reading