title: The incidence of bone metastasis after early-stage breast cancer in Canada.
abstract: Current information on the incidence and prevalence of bone metastases in women with breast cancer is scarce. This study examined the occurrence and predictors of bone metastases, as well as post-metastasis survival in a prospective cohort of Canadian women with breast cancer. We included women treated for early-stage (stage I, II, or III) breast cancer at the Henrietta Banting Breast Centre (HBBC) in Toronto, Canada between 1987 and 2000. Data were abstracted from medical records and pathology reports in the HBBC database; follow-up extended to end of data availability or August 31, 2015. Actuarial survival analyses provided cumulative incidence of bone metastases at 5, 10, and 15 years after breast cancer diagnosis. Kaplan-Meier curves describe breast cancer mortality. Regression models assessed patient, tumor, and treatment characteristics as predictors of bone metastases with all-cause mortality as a competing risk. Among 2097 women studied, the 5-, 10-, and 15-year probability of bone metastasis was 6.5, 10.3, and 11.3 % for the first recurrence, and 8.4, 12.5, and 13.6 % for any bone recurrence. At median follow-up (12.5 years), 13.2 % of patients had bone metastases. Median survival was 1.6 years following bone metastasis, and shorter if both bone and visceral metastases occurred. Advanced age and adjuvant treatment with tamoxifen were protective against bone metastasis. In this representative cohort of women diagnosed with early-stage breast cancer in Ontario, Canada, with long follow-up, the incidence of bone metastases was consistent with longitudinal studies from the United Kingdom, Denmark, and the US.
authors.affiliation: Center for Observational Research, Amgen Inc, South San Francisco and Thousand Oaks, CA, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Liede
authors.affiliation: University of Toronto, Toronto, ON, Canada.
authors.forename: Katarzyna J
authors.initials: KJ
authors.lastname: Jerzak
authors.affiliation: Center for Observational Research, Amgen Inc, South San Francisco and Thousand Oaks, CA, USA.
authors.forename: Rohini K
authors.initials: RK
authors.lastname: Hernandez
authors.affiliation: Wade Outcomes Research and Consulting, Salt Lake City, UT, USA.
authors.forename: Sally W
authors.initials: SW
authors.lastname: Wade
authors.affiliation: Women's College Research Institute, Women's College Hospital, 76 Grenville Street, 6th Floor, Toronto, ON, M5S 1B2, Canada.
authors.forename: Ping
authors.initials: P
authors.lastname: Sun
authors.affiliation: Women's College Research Institute, Women's College Hospital, 76 Grenville Street, 6th Floor, Toronto, ON, M5S 1B2, Canada. steven.narod@wchospital.ca.|University of Toronto, Toronto, ON, Canada. steven.narod@wchospital.ca.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Narod
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000453:epidemiology* / Q000556:secondary*; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D002170:Canada / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D017741:Survivors / Q000706:statistics & numerical data; D055815:Young Adult
keywords: Bone metastases; Breast cancer; Follow-up; Mortality