Breast Surgery
Breast Implants and the Risk of Breast Cancer: A Meta-Analysis of Cohort Studies
Aesthetic Surgery Journal 2015, Vol 35(1) 55–62 © 2015 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: [email protected] DOI: 10.1093/asj/sju006 www.aestheticsurgeryjournal.com
Eline C. Noels, MD; Oren Lapid, MD, PhD; Jan H.N. Lindeman, MD, PhD; and Esther Bastiaannet, PhD
Abstract Background: The popularity of cosmetic breast augmentation and the incidence of breast cancer have been increasing worldwide. It has been hypothesized that the risk of breast cancer may be greater among patients who have undergone cosmetic breast implantation. Objectives: The authors performed a meta-analysis of the available literature on the risk of breast cancer among women with cosmetic breast implants. Methods: The study was designed as a meta-analysis of observational studies. A systematic search of the English literature ( published by August 28, 2013) was conducted in PubMed and EMBASE. Eligible reports were those that included relative risk (RR; the increased or decreased risk of breast cancer associated with breast implants) or the standardized incidence ratio (SIR) of the observed number of cases of breast cancer to the expected number of cases among patients that previously underwent cosmetic breast augmentation. Results: Seventeen studies representing 7 cohorts were selected. Some of these were follow-up reports of previously published studies; in such cases, only the most recent reports were included in the meta-analysis. Summary SIR and RR rates and the corresponding 95% confidence intervals (CIs) were calculated with a random-effects (SIR) or fixed-effects (RR) model. The overall SIR estimate was 0.69 (95% CI, 0.56-0.85), and the overall RR, based on 4 studies, was 0.63 (95% CI, 0.56-0.71). Conclusions: Finding of this meta-analysis suggest that women who have undergone cosmetic breast implantation do not have an increased risk of breast cancer. Accepted for publication May 22, 2014.
Breast augmentation is one of the most common cosmetic surgical procedures worldwide, with more than 1.2 million procedures performed in 2011.1 In the United States alone, over 330,000 procedures were performed in 2012.2 As the rate of breast augmentation procedures has increased, so has the incidence of breast cancer among all women. In 2010, 1,643,000 cases of breast cancer were diagnosed worldwide, reflecting an annual increase of 3.1% between 1980 and 2010.3 Thus, it may be hypothesized that breast implants contribute to the development of breast cancer. However, this notion has not been supported by the available literature, which actually suggests a lower risk of breast cancer among patients with breast implants.4 Although interpretation of the published studies is hampered by potential biases and confounders,5 it is possible that pooling the results might demonstrate a stronger correlation. Meta-analysis involves combining the statistical results of similar studies, with the goal of improving the precision of estimates. Many types of studies can be pooled, provided their designs and outcome measures are similar.6 The
present meta-analysis was performed with state-of-the-art data analysis techniques.
METHODS This meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Dr Noels is a researcher and Dr Lapid is a plastic surgeon in the Department of Plastic, Reconstructive, and Hand Surgery, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands. Dr Lindeman is a senior researcher in the Department of Vascular Surgery, and Dr Bastiaannet is an epidemiologist and senior researcher in the Department of Surgery and Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, the Netherlands. Corresponding Author: Dr Oren Lapid, Department of Plastic, Reconstructive and Hand Surgery, Academic Medical Center, University of Amsterdam, Room G7-251, Meibergdreef 9, Postbus 22660, 1100 DD Amsterdam, the Netherlands. E-mail: [email protected]
Aesthetic Surgery Journal 35(1)
56
Meta-Analyses (PRISMA) statement for reporting systematic reviews and meta-analyses.7
Publication Search A literature search was performed in PubMed and EMBASE on August 28, 2013, for English-language articles published in all years. Articles not yet indexed for Medline were included. The search strategy for both databases included terms for exposure (breast implant, breast prosthesis, breast augmentation) and for outcome (breast cancers, breast neoplasm, mammary carcinoma, and mammary neoplasm). (Search criteria appear in Appendix A, which is available online at www.aestheticsurgeryjournal.com.) The search results included epidemiologic studies, case reports, literature reviews, and letters. The references in relevant literature were checked for possible additional articles. The search strategy was reviewed by a reference librarian. Initially, the titles and abstracts of the publications were retrieved.
Inclusion Criteria Screening of the titles and abstracts was performed by 2 authors (E.C.N. and O.L.). Any articles that raised inclusion concerns were discussed with a third author (E.B.). Studies were required to meet the following inclusion criteria: (1) cohort design, (2) exposure of interest was breast implants, (3) outcome of interest was breast cancer, and (4) data on standardized incidence ratio (SIR) or relative risk (RR) with 95% confidence intervals (CIs). There were no restrictions for patient age or duration of follow-up. Update reports for similar study populations were permitted. Cohort studies on patients receiving breast implants for reconstructive purposes were excluded.
Relative Risk and Standardized Incidence Ratio The RR indicates the increased or decreased risk of disease associated with exposure to the factor of interest. An RR of 1 indicates that the risk is similar for the exposed and unexposed groups. RR >1 indicates that the exposed group has an increased risk compared with the unexposed group, and RR
Breast Implants and the Risk of Breast Cancer: A Meta-Analysis of Cohort Studies
Aesthetic Surgery Journal 2015, Vol 35(1) 55–62 © 2015 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: [email protected] DOI: 10.1093/asj/sju006 www.aestheticsurgeryjournal.com
Eline C. Noels, MD; Oren Lapid, MD, PhD; Jan H.N. Lindeman, MD, PhD; and Esther Bastiaannet, PhD
Abstract Background: The popularity of cosmetic breast augmentation and the incidence of breast cancer have been increasing worldwide. It has been hypothesized that the risk of breast cancer may be greater among patients who have undergone cosmetic breast implantation. Objectives: The authors performed a meta-analysis of the available literature on the risk of breast cancer among women with cosmetic breast implants. Methods: The study was designed as a meta-analysis of observational studies. A systematic search of the English literature ( published by August 28, 2013) was conducted in PubMed and EMBASE. Eligible reports were those that included relative risk (RR; the increased or decreased risk of breast cancer associated with breast implants) or the standardized incidence ratio (SIR) of the observed number of cases of breast cancer to the expected number of cases among patients that previously underwent cosmetic breast augmentation. Results: Seventeen studies representing 7 cohorts were selected. Some of these were follow-up reports of previously published studies; in such cases, only the most recent reports were included in the meta-analysis. Summary SIR and RR rates and the corresponding 95% confidence intervals (CIs) were calculated with a random-effects (SIR) or fixed-effects (RR) model. The overall SIR estimate was 0.69 (95% CI, 0.56-0.85), and the overall RR, based on 4 studies, was 0.63 (95% CI, 0.56-0.71). Conclusions: Finding of this meta-analysis suggest that women who have undergone cosmetic breast implantation do not have an increased risk of breast cancer. Accepted for publication May 22, 2014.
Breast augmentation is one of the most common cosmetic surgical procedures worldwide, with more than 1.2 million procedures performed in 2011.1 In the United States alone, over 330,000 procedures were performed in 2012.2 As the rate of breast augmentation procedures has increased, so has the incidence of breast cancer among all women. In 2010, 1,643,000 cases of breast cancer were diagnosed worldwide, reflecting an annual increase of 3.1% between 1980 and 2010.3 Thus, it may be hypothesized that breast implants contribute to the development of breast cancer. However, this notion has not been supported by the available literature, which actually suggests a lower risk of breast cancer among patients with breast implants.4 Although interpretation of the published studies is hampered by potential biases and confounders,5 it is possible that pooling the results might demonstrate a stronger correlation. Meta-analysis involves combining the statistical results of similar studies, with the goal of improving the precision of estimates. Many types of studies can be pooled, provided their designs and outcome measures are similar.6 The
present meta-analysis was performed with state-of-the-art data analysis techniques.
METHODS This meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Dr Noels is a researcher and Dr Lapid is a plastic surgeon in the Department of Plastic, Reconstructive, and Hand Surgery, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands. Dr Lindeman is a senior researcher in the Department of Vascular Surgery, and Dr Bastiaannet is an epidemiologist and senior researcher in the Department of Surgery and Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, the Netherlands. Corresponding Author: Dr Oren Lapid, Department of Plastic, Reconstructive and Hand Surgery, Academic Medical Center, University of Amsterdam, Room G7-251, Meibergdreef 9, Postbus 22660, 1100 DD Amsterdam, the Netherlands. E-mail: [email protected]
Aesthetic Surgery Journal 35(1)
56
Meta-Analyses (PRISMA) statement for reporting systematic reviews and meta-analyses.7
Publication Search A literature search was performed in PubMed and EMBASE on August 28, 2013, for English-language articles published in all years. Articles not yet indexed for Medline were included. The search strategy for both databases included terms for exposure (breast implant, breast prosthesis, breast augmentation) and for outcome (breast cancers, breast neoplasm, mammary carcinoma, and mammary neoplasm). (Search criteria appear in Appendix A, which is available online at www.aestheticsurgeryjournal.com.) The search results included epidemiologic studies, case reports, literature reviews, and letters. The references in relevant literature were checked for possible additional articles. The search strategy was reviewed by a reference librarian. Initially, the titles and abstracts of the publications were retrieved.
Inclusion Criteria Screening of the titles and abstracts was performed by 2 authors (E.C.N. and O.L.). Any articles that raised inclusion concerns were discussed with a third author (E.B.). Studies were required to meet the following inclusion criteria: (1) cohort design, (2) exposure of interest was breast implants, (3) outcome of interest was breast cancer, and (4) data on standardized incidence ratio (SIR) or relative risk (RR) with 95% confidence intervals (CIs). There were no restrictions for patient age or duration of follow-up. Update reports for similar study populations were permitted. Cohort studies on patients receiving breast implants for reconstructive purposes were excluded.
Relative Risk and Standardized Incidence Ratio The RR indicates the increased or decreased risk of disease associated with exposure to the factor of interest. An RR of 1 indicates that the risk is similar for the exposed and unexposed groups. RR >1 indicates that the exposed group has an increased risk compared with the unexposed group, and RR
