title: Can we select individuals with low risk ductal carcinoma in situ (DCIS)? A population-based outcomes analysis.
abstract: Ductal carcinoma in situ (DCIS), a non-invasive breast cancer, is usually treated by breast-conserving surgery (BCS). Randomized trials prove that the addition of radiotherapy (XRT) leads to lower rates of recurrence. Despite the evidence, half of women do not receive XRT after BCS. It is unknown how well clinicians identify women with low risk DCIS for treatment by BCS alone or to what extent women with DCIS develop recurrent cancer due to the omission of radiotherapy. We report the outcomes of a population of women with DCIS treated with BCS, alone or with radiotherapy, and evaluate the effectiveness of each therapeutic approach. All women diagnosed with DCIS and treated with BCS, alone or with radiotherapy in Ontario from 1994 to 2003 were identified. Treatments and outcomes were validated by chart review. Survival analyses were used to study the development of local recurrence (LR) in relation to patient and tumor characteristics and the use of radiotherapy. The cohort included 3,762 women treated with breast-conserving therapy; 1,895 of whom (50 %) also received radiation. At 10 years median follow-up, LR developed in 233 (12 %) women who received radiotherapy and in 363 (19 %) of women who did not (p < 0.0001). The 10-year actuarial LR rate for women who did and did not receive radiotherapy was 12.7 and 20.0 % (p < 0.0001). Differences were significant for both for invasive LR (7.0 vs. 10.0 %, p < 0.0001) and for DCIS recurrence (6.1 vs. 10.8 %, p < 0.0001). We estimate that 22 % of recurrences diagnosed in Ontario women treated for DCIS between 1994 and 2003 would have been prevented if all patients had received radiotherapy. The omission of radiotherapy after BCS for DCIS resulted in substantive recurrences that might have been avoided with treatment. Additional markers are needed to identify a low risk group in whom radiation can be safely omitted.
authors: Department of Radiation Oncology, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. eileen.rakovitch@sunnybrook.ca
authors: Eileen
authors: E
authors: Rakovitch
authors: Sharon
authors: S
authors: Nofech-Mozes
authors: Steven A
authors: SA
authors: Narod
authors: Wedad
authors: W
authors: Hanna
authors: Deva
authors: D
authors: Thiruchelvam
authors: Refik
authors: R
authors: Saskin
authors: Carole
authors: C
authors: Taylor
authors: Alan
authors: A
authors: Tuck
authors: Sandip
authors: S
authors: Sengupta
authors: Leela
authors: L
authors: Elavathil
authors: Prashant A
authors: PA
authors: Jani
authors: Susan J
authors: SJ
authors: Done
authors: Naomi
authors: N
authors: Miller
authors: Bruce
authors: B
authors: Youngson
authors: Iwa
authors: I
authors: Kong
authors: Lawrence
authors: L
authors: Paszat
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000532:radiotherapy / Q000601:surgery; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000453:epidemiology* / Q000532:radiotherapy / Q000601:surgery; D015331:Cohort Studies; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D015994:Incidence; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology* / Q000517:prevention & control; D009864:Ontario / Q000453:epidemiology; D011153:Population; D012306:Risk; D016896:Treatment Outcome; D055815:Young Adult