title: Risk of second non-hematological malignancies among 376,825 breast cancer survivors.
abstract: Breast cancer survivors are at increased risk of treatment-related second cancers. This study is the first to examine risk 30 or more years after diagnosis and to present absolute risks of second cancer which accounts for competing mortality. We identified 23,158 second non-hematological malignancies excluding breast in a population-based cohort of 376,825 one-year survivors of breast cancer diagnosed from 1943 to 2002 and reported to four Scandinavian cancer registries. We calculated standardized incidence ratios (SIR) and utilized a competing-risk model to calculate absolute risk of developing second cancers. The overall SIR for second cancers was 1.15 (95% confidence interval [CI] = 1.14-1.17). The SIR for potentially radiotherapy-associated cancers 30 or more years after breast cancer diagnosis was 2.19 (95% CI = 1.87-2.55). However, the largest SIRs were observed for women aged <40 years followed for 1-9 years. At 20 years after breast cancer diagnosis, the absolute risk of developing a second cancer ranged from 0.6 to 10.3%, depending on stage and age; the difference in the absolute risk compared to the background population was greatest for women aged <40 years with localized disease, 2.3%. At 30 years post breast cancer diagnosis, this difference reached 3.2%. These risks were small compared to the corresponding risk of dying from breast cancer. Although the absolute risks were small, we found persistent risks of second non-hematological malignancies excluding breast 30 or more years after breast cancer diagnosis, particularly for women diagnosed at young ages with localized disease.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, 6120 Executive Blvd, MSC 7244, Bethesda, MD 20892-7244, USA. brownl@mail.nih.gov
authors.forename: Linda Morris
authors.initials: LM
authors.lastname: Brown
authors.forename: Bingshu E
authors.initials: BE
authors.lastname: Chen
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Pfeiffer
authors.forename: Catherine
authors.initials: C
authors.lastname: Schairer
authors.forename: Per
authors.initials: P
authors.lastname: Hall
authors.forename: Hans
authors.initials: H
authors.lastname: Storm
authors.forename: Eero
authors.initials: E
authors.lastname: Pukkala
authors.forename: Frøydis
authors.initials: F
authors.lastname: Langmark
authors.forename: Magnus
authors.initials: M
authors.lastname: Kaijser
authors.forename: Michael
authors.initials: M
authors.lastname: Andersson
authors.forename: Heikki
authors.initials: H
authors.lastname: Joensuu
authors.forename: Sophie D
authors.initials: SD
authors.lastname: Fosså
authors.forename: Lois B
authors.initials: LB
authors.lastname: Travis
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000150:complications* / Q000532:radiotherapy; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000209:etiology*; D012306:Risk; D017741:Survivors