Breast Cancer Mortality After a Diagnosis of Ductal Carcinoma In Situ.
OBJECTIVE
Women with ductal carcinoma in situ (DCIS), or stage 0 breast cancer, often experience a second primary breast cancer (DCIS or invasive), and some ultimately die of breast cancer.


OBJECTIVE
To estimate the 10- and 20-year mortality from breast cancer following a diagnosis of DCIS and to establish whether the mortality rate is influenced by age at diagnosis, ethnicity, and initial treatment received.


METHODS
Observational study of women who received a diagnosis of DCIS from 1988 to 2011 in the Surveillance, Epidemiology, and End Results (SEER) 18 registries database. Age at diagnosis, race/ethnicity, pathologic features, date of second primary breast cancer, cause of death, and survival were abstracted for 108,196 women. Their risk of dying of breast cancer was compared with that of women in the general population. Cox proportional hazards analysis was performed to estimate the hazard ratio (HR) for death from DCIS by age at diagnosis, clinical features, ethnicity, and treatment.


METHODS
Ten- and 20-year breast cancer-specific mortality.


RESULTS
Among the 108 196 women with DCIS, the mean (range) age at diagnosis of DCIS was 53.8 (15-69) years and the mean (range) duration of follow-up was 7.5 (0-23.9) years. At 20 years, the breast cancer-specific mortality was 3.3% (95% CI, 3.0%-3.6%) overall and was higher for women who received a diagnosis before age 35 years compared with older women (7.8% vs 3.2%; HR, 2.58 [95% CI, 1.85-3.60]; P < .001) and for blacks compared with non-Hispanic whites (7.0% vs 3.0%; HR, 2.55 [95% CI, 2.17-3.01]; P < .001). The risk of dying of breast cancer increased after experience of an ipsilateral invasive breast cancer (HR, 18.1 [95% CI, 14.0-23.6]; P < .001). A total of 517 patients died of breast cancer following a DCIS diagnosis (mean follow-up, 7.5 [range, 0-23.9] years) without experiencing an in-breast invasive cancer prior to death. Among patients who received lumpectomy, radiotherapy was associated with a reduction in the risk of ipsilateral invasive recurrence at 10 years (2.5% vs 4.9%; adjusted HR, 0.47 [95% CI, 0.42-0.53]; P < .001) but not of breast cancer-specific mortality at 10 years (0.8% vs 0.9%; HR, 0.86 [95% CI, 0.67-1.10]; P = .22).


CONCLUSIONS
Important risk factors for death from breast cancer following a DCIS diagnosis include age at diagnosis and black ethnicity. The risk of death increases after a diagnosis of an ipsilateral second primary invasive breast cancer, but prevention of these recurrences by radiotherapy does not diminish breast cancer mortality at 10 years.
Women's College Research Institute, Women's College Hospital, Toronto, Ontario, Canada2Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
Steven A
SA
Narod
Women's College Research Institute, Women's College Hospital, Toronto, Ontario, Canada.
Javaid
J
Iqbal
Women's College Research Institute, Women's College Hospital, Toronto, Ontario, Canada2Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
Vasily
V
Giannakeas
Women's College Research Institute, Women's College Hospital, Toronto, Ontario, Canada.
Victoria
V
Sopik
Women's College Research Institute, Women's College Hospital, Toronto, Ontario, Canada.
Ping
P
Sun
D000293:Adolescent; D000328:Adult; D001741:Black or African American; D000367:Age Factors; D000368:Aged; D001943:Breast Neoplasms / Q000208:ethnology / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000208:ethnology / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D002423:Cause of Death; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D015412:Mastectomy, Segmental; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D016017:Odds Ratio; D016016:Proportional Hazards Models; D018714:Radiotherapy, Adjuvant; D018570:Risk Assessment; D012307:Risk Factors; D018426:SEER Program; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D055815:Young Adult