Breast Cancer

PV QA 4 - Poster Viewing Q&A 4

TU_4_3353 - Secondary Breast Cancer after DCIS: Impact of Initial Radiation Therapy on Mortality Associated With Invasive Second Breast Cancers

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

Secondary Breast Cancer after DCIS: Impact of Initial Radiation Therapy on Mortality Associated With Invasive Second Breast Cancers
P. C. Li1, A. M. Cronin2, and R. S. Punglia3; 1Brigham and Women's Hospital/Dana-Farber Cancer Institute/Massachusetts General Hospital, Boston, MA, 2Dana-Farber Cancer Institute, Boston, MA, 3Brigham and Women's Hospital/Dana-Farber Cancer Institute, Boston, MA

Purpose/Objective(s): Women with a history of DCIS are at increased risk for developing a second breast cancer (SBC), either in the ipsilateral or contralateral breast. Treatments for DCIS currently include mastectomy or breast-conserving surgery with or without radiation therapy (RT). The addition of RT following breast-conserving surgery has been shown to decrease the risk of local recurrence, including recurrence of an invasive SBC, but has not been demonstrated to affect mortality. We seek to evaluate the impact of radiation on the characteristics of SBC and breast-cancer specific survival following SBC.

Materials/Methods: We identified 5469 patients who received breast conserving surgery (+/- RT) between 2000-2013 for primary DCIS and had a SBC diagnosis (stage 0-IV) in SEER. Characteristics of SBC were described, and survival analyses were performed for the subset with stage I-III SBC (N=3487). Multivariable competing risk regression models were fit to assess the association between receipt of RT for primary DCIS and time to BC-specific death; survival time started on the date of SBC with follow-up through 2013. Interaction analyses were conducted to explore whether an association between receipt of RT for primary DCIS and BC-specific death was modified by laterality of SBC.

Results: Among 5469 patients, 2605 (48%) had ipsilateral and 2864 (52%) had contralateral SBC. Patients who developed ipsilateral (versus contralateral) SBC were younger at the time of their primary and secondary diagnoses (p<0.001), were less likely to have ER expression for both diagnoses (p<0.001), and had longer interval to SBC (p<0.001). The likelihood of SBC being invasive was 67% and 71% in the ipsilateral breast, with and without RT (p=0.04), respectively; and 64% and 68% in the contralateral breast (p=0.02). Following stage I-III SBC, 5-year cumulative incidence of BC-specific death was 8.0% with prior RT vs. 4.7% without for ipsilateral SBC; and 5.3% with prior RT vs. 4.2% without for contralateral SBC. In a multivariable competing risk analysis, prior radiotherapy was significantly associated with increased BC-specific mortality (HR 1.70; 95% CI 1.18-2.45; p = 0.005). Interaction analysis suggested that this association differed by laterality of SBC (HR 2.07 for ipsilateral vs. 1.26 for contralateral SBC), although the interaction was not statistically significant (p=0.16). Other factors independently associated with cancer-specific mortality following SBC included age at SBC diagnosis (p <0.001), and ER status (p<0.001) and stage of SBC (p <0.001).

Conclusion: Among patients with invasive SBC after a DCIS diagnosis, prior RT was associated with increased breast cancer-specific mortality. This increase was particularly pronounced in patients with ipsilateral SBC. These findings may have implications for decision-making about treatment for DCIS and at time of SBC.

Author Disclosure: P.C. Li: None. A.M. Cronin: None. R.S. Punglia: None.

Send Email for Puyao Li


Assets

TU_4_3353 - Secondary Breast Cancer after DCIS: Impact of Initial Radiation Therapy on Mortality Associated With Invasive Second Breast Cancers



Attendees who have favorited this

Please enter your access key

The asset you are trying to access is locked. Please enter your access key to unlock.

Send Email for Secondary Breast Cancer after DCIS: Impact of Initial Radiation Therapy on Mortality Associated With Invasive Second Breast Cancers