Eileen Rakovitch1,2,3,4, Rinku Sutradhar5,6, Nafisha Lalani7,6, Sharon Nofech-Mozes8,6, Sumei Gu5, Mira Goldberg9, Wedad Hanna8,6, Cindy Fong5, Lawrence Paszat7. 1. Department of Radiation Oncology, Toronto, ON, Canada. eileen.rakovitch@sunnybrook.ca. 2. ICES, Toronto, ON, Canada. eileen.rakovitch@sunnybrook.ca. 3. Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada. eileen.rakovitch@sunnybrook.ca. 4. LC Campbell Chair in Breast Cancer Research, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. eileen.rakovitch@sunnybrook.ca. 5. ICES, Toronto, ON, Canada. 6. Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada. 7. Department of Radiation Oncology, Toronto, ON, Canada. 8. Department of Pathology, Sunnybrook Health Sciences Centre, Toronto, ON, Canada. 9. Department of Oncology, McMaster University, Hamilton, ON, Canada.
Abstract
PURPOSE: The impact of Ductal Carcinoma in Situ (DCIS) with multiple foci of microinvasion (MI) (≤ 1 mm) on the risks of local recurrence (LR) and invasive LR is unknown, leading to uncertainty if DCIS with multiple foci of MI requires more aggressive treatment. We report a population-based analysis of the impact of multiple foci of MI, confirmed by pathology review, on the 15-year risks of LR and invasive LR treated with breast-conserving surgery (BCS) ± radiotherapy (RT). METHODS: Cohort includes all women diagnosed with DCIS ± MI from 1994 to 2003 treated with BCS ± RT. Cox proportional hazards model was used to evaluate the impact of multiple foci of MI on the risks of LR and invasive LR, adjusting for covariates. The 15-year local and invasive local recurrence-free survival rates were calculated using the Kaplan-Meier method with differences compared by log-rank test. RESULTS: The cohort includes 2988 women treated by BCS; 2721 had pure DCIS (51% received RT), 267 had DCIS with one or more foci of MI (58% had RT). Median follow-up was 13 years. Median age at diagnosis was 58 years. On multivariable analyses, the presence of multiple foci of MI was associated with an increased risk of invasive LR (HR = 1.59, 95% CI 1.01-2.49, p = 0.04) but not DCIS LR (HR = 0.89, 95% CI 0.46, 1.76, p = 0.7). The 15-year invasive LRFS risks for cases with pure DCIS, with 1 focus or multiple foci of MI were 85.7%, 85.6%, 74.7% following treatment by BCS alone, 87.2%, 89.9%, and 77% for those treated with BCS + RT without boost and 89.2%, 91.3%, and 95% for women treated with BCS + RT and boost. CONCLUSIONS: The presence of multiple foci of MI in DCIS is associated with higher 15-year risks of invasive LR after breast-conserving therapy compared to women with pure DCIS but treatment with whole breast and boost RT can mitigate this risk.
PURPOSE: The impact of Ductal Carcinoma in Situ (DCIS) with multiple foci of microinvasion (MI) (≤ 1 mm) on the risks of local recurrence (LR) and invasive LR is unknown, leading to uncertainty if DCIS with multiple foci of MI requires more aggressive treatment. We report a population-based analysis of the impact of multiple foci of MI, confirmed by pathology review, on the 15-year risks of LR and invasive LR treated with breast-conserving surgery (BCS) ± radiotherapy (RT). METHODS: Cohort includes all women diagnosed with DCIS ± MI from 1994 to 2003 treated with BCS ± RT. Cox proportional hazards model was used to evaluate the impact of multiple foci of MI on the risks of LR and invasive LR, adjusting for covariates. The 15-year local and invasive local recurrence-free survival rates were calculated using the Kaplan-Meier method with differences compared by log-rank test. RESULTS: The cohort includes 2988 women treated by BCS; 2721 had pure DCIS (51% received RT), 267 had DCIS with one or more foci of MI (58% had RT). Median follow-up was 13 years. Median age at diagnosis was 58 years. On multivariable analyses, the presence of multiple foci of MI was associated with an increased risk of invasive LR (HR = 1.59, 95% CI 1.01-2.49, p = 0.04) but not DCIS LR (HR = 0.89, 95% CI 0.46, 1.76, p = 0.7). The 15-year invasive LRFS risks for cases with pure DCIS, with 1 focus or multiple foci of MI were 85.7%, 85.6%, 74.7% following treatment by BCS alone, 87.2%, 89.9%, and 77% for those treated with BCS + RT without boost and 89.2%, 91.3%, and 95% for women treated with BCS + RT and boost. CONCLUSIONS: The presence of multiple foci of MI in DCIS is associated with higher 15-year risks of invasive LR after breast-conserving therapy compared to women with pure DCIS but treatment with whole breast and boost RT can mitigate this risk.
Entities:
Keywords:
DCIS; Ductal carcinoma in situ; Local recurrence; Microinvasion; Radiotherapy