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The impact of reproductive factors on breast cancer risk - The feasibility of using Swedish population-based registers to account for the effect of confounding in cohort studies

Holmberg, E; Anderson, Harald LU ; Lundell, M and Karlsson, P (2005) In Cancer Causes and Control 16(3). p.235-243
Abstract
Objective: The aim of this study was to analyze the impact of reproductive factors on breast cancer risk among Swedish women by using nationwide population registers. Methods: A cohort including all Swedish women born between 1920 and 1959 was followed up to 1997 by record linkage to different population-based registers. More than 4 million children were linked to the women in the cohort and 60,328 women were diagnosed with breast cancer. Poisson regression was used to model the breast cancer incidence by risk groups. In a sub-cohort of 18,164 women irradiated for skin hemangioma in infancy, the breast cancer risk was analyzed in relation to radiation dose and accounting for reproductive factors. Results: The relative breast cancer risk... (More)
Objective: The aim of this study was to analyze the impact of reproductive factors on breast cancer risk among Swedish women by using nationwide population registers. Methods: A cohort including all Swedish women born between 1920 and 1959 was followed up to 1997 by record linkage to different population-based registers. More than 4 million children were linked to the women in the cohort and 60,328 women were diagnosed with breast cancer. Poisson regression was used to model the breast cancer incidence by risk groups. In a sub-cohort of 18,164 women irradiated for skin hemangioma in infancy, the breast cancer risk was analyzed in relation to radiation dose and accounting for reproductive factors. Results: The relative breast cancer risk (RR) for the reproductive factors was 0.35 [ 95% confidence interval (CI) 0.30-0.42] for women with 6 or more children and the first child before the age of 20 years, and RR was 1.11 (95% CI 1.06-1.18) for uniparous women with the first child at age 35 years or older, compared to nulliparous women. The discrepancies of reproductive factors in the hemangioma cohort compared to Swedish women had a minor effect on RR, with a reduction from 1.13 (95%CI 1.00-1.26) to 1.11 (95% CI 0.99-1.25). Conclusions: This study shows the feasibility of using population-based registers to retrieve reliable information on reproductive factors to eliminate its confounding effect when analyzing other risk factors. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
history, reproductive, confounding factors, breast neoplasms, cohort studies, ionizing radiation
in
Cancer Causes and Control
volume
16
issue
3
pages
235 - 243
publisher
Springer
external identifiers
  • pmid:15947875
  • wos:000229736900005
  • scopus:21244467592
ISSN
1573-7225
DOI
10.1007/s10552-004-3363-3
language
English
LU publication?
yes
id
3ee0cb5c-b903-4c73-a5cb-2590f3efadf0 (old id 236287)
date added to LUP
2007-09-28 09:31:34
date last changed
2017-08-20 03:47:30
@article{3ee0cb5c-b903-4c73-a5cb-2590f3efadf0,
  abstract     = {Objective: The aim of this study was to analyze the impact of reproductive factors on breast cancer risk among Swedish women by using nationwide population registers. Methods: A cohort including all Swedish women born between 1920 and 1959 was followed up to 1997 by record linkage to different population-based registers. More than 4 million children were linked to the women in the cohort and 60,328 women were diagnosed with breast cancer. Poisson regression was used to model the breast cancer incidence by risk groups. In a sub-cohort of 18,164 women irradiated for skin hemangioma in infancy, the breast cancer risk was analyzed in relation to radiation dose and accounting for reproductive factors. Results: The relative breast cancer risk (RR) for the reproductive factors was 0.35 [ 95% confidence interval (CI) 0.30-0.42] for women with 6 or more children and the first child before the age of 20 years, and RR was 1.11 (95% CI 1.06-1.18) for uniparous women with the first child at age 35 years or older, compared to nulliparous women. The discrepancies of reproductive factors in the hemangioma cohort compared to Swedish women had a minor effect on RR, with a reduction from 1.13 (95%CI 1.00-1.26) to 1.11 (95% CI 0.99-1.25). Conclusions: This study shows the feasibility of using population-based registers to retrieve reliable information on reproductive factors to eliminate its confounding effect when analyzing other risk factors.},
  author       = {Holmberg, E and Anderson, Harald and Lundell, M and Karlsson, P},
  issn         = {1573-7225},
  keyword      = {history,reproductive,confounding factors,breast neoplasms,cohort studies,ionizing radiation},
  language     = {eng},
  number       = {3},
  pages        = {235--243},
  publisher    = {Springer},
  series       = {Cancer Causes and Control},
  title        = {The impact of reproductive factors on breast cancer risk - The feasibility of using Swedish population-based registers to account for the effect of confounding in cohort studies},
  url          = {http://dx.doi.org/10.1007/s10552-004-3363-3},
  volume       = {16},
  year         = {2005},
}