[101] Contralateral Breast Cancer Risk Following a Diagnosis of Ductal Carcinom In Situ

Fouad I Boulos, Jean F Simpson, Peggy A Schuyler, William D Dupont, David L Page, Melinda E Sanders. American University of Beruit, Beruit, Riad El Solh, Lebanon; Vanderbilt University, Nashville, TN

Background: The number of women choosing contralateral prophylactic mastectomy following a diagnosis of ductal carcinoma (DCIS) appears to be on the rise. The risk of subsequent contralateral invasive breast cancer (IBC) following a diagnosis of IBC is well established (approximately 0.5-1.0% per year). Natural history studies of DCIS indicate risk is exclusively ipsilateral but follow-up data from retrospective and prospective intent-to-treat studies clearly demonstrate a range of contralateral risk.
Design: We assessed contralateral breast cancer risk in women enrolled in the Nashville Breast Cohort diagnosed as having DCIS between 1950-2009, no prior history of IBC and at least contralateral remaining breast tissue. Laterality, cancer type, cancer grade and time to cancer diagnosis were correlated with survival.
Results: Among 288 women with a diagnosis of DCIS and available follow-up, 41 (14%) developed a subsequent IBC in either breast at an average of 8 years (range 1-42 yrs) and 14 (4.8%) developed a second DCIS in either breast at an average of 8 yrs (range 2-25 yrs) after their original DCIS diagnosis. Laterality of IBC: 29 (10%) ipsilateral, 9 (3.1%) contralateral, 3 unknown. Laterality of second DCIS: 7 (2.4%) ipsilateral, 6 (2.1%) contralateral, 1 unknown. The average time to ipsilateral IBC was 8.9 yrs (range 1-42) vs. 5.2 yrs (range 1-14) for contralateral IBC. The average time to ipsilateral DCIS was 7 yrs (range 3-25) vs. 4.2 yrs (range 3-6) for contralateral DCIS. There was no apparent relationship between the type and grade of the initial DCIS and the contralaterally-occurring IBC or second DCIS. The grade of the ipsilaterally-occurring IBC and second DCIS generally paralleled grade of the original DCIS. There were 7 breast cancer deaths among women developing ipsilateral IBC but none in the women with contralateral IBC.
Conclusions: The risk of contralateral IBC following a diagnosis of DCIS in this population based cohort (3%) is less than one third that of ipsilateral risk (10%) but with an earlier occurrence. Interestingly, the risk of contralateral DCIS (2.4%) was approximately the same as ipsilateral DCIS (2.1%), likely the result of greater tendency to treat the incident DCIS by mastectomy in the early years of this study. We found risk of contralateral IBC following a diagnosis of DCIS to be 0.22% per year. This rate is comparable to the 0.34% yearly incidence rate in the general population, and our data suggest prophylactic contralateral mastectomy following a diagnosis of DCIS provides no survival advantage.
Category: Breast

Monday, March 19, 2012 1:45 PM

Platform Session: Section B, Monday Afternoon


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