Cancer risk among Danish women with cosmetic breast implants

Abstract

The available epidemiologic evidence does not support a carcinogenic effect of silicone breast implants on breast or other cancers. Data on cancer risk other than breast cancer are limited and few studies have assessed cancer risk beyond 10-15 years after breast implantation. We extended follow-up of our earlier cohort study of Danish women with cosmetic breast implants by 7 years, yielding 30 years of follow-up for women with longest implant duration. The study population consisted of women who underwent cosmetic breast implant surgery at private clinics of plastic surgery (n 5 1,653) or public hospitals (n 5 1,110), and a control group of women who attended private clinics for other plastic surgery (n 5 1,736), between 1973-95. Cancer incidence through 2002 was ascertained using the Danish Cancer Registry. Risk evaluation was based on computation of standardized incidence ratios (SIR) and Cox proportional hazards models, adjusting for age, calendar period and reproductive history. We observed 163 cancers among women with breast implants compared to 136.7 expected based on general population rates (SIR 5 1.2; 95% confidence interval [CI] 5 1.0-1.4), during a mean follow-up period of 14.4 years (range 5 0-30 years). Women with breast implants experienced a reduced risk of breast cancer (SIR 5 0.7; 95% CI 5 0.5-1.0), and an increased risk of non-melanoma skin cancer (SIR 5 2.1; 95% CI 5 1.5-2.7). Stratification by age at implantation, calendar year at implantation and time since implantation showed no clear trends, however, the statistical precision was limited in these analyses. When excluding non-melanoma skin cancer, the SIR for cancer overall was 1.0 (95% CI 5 0.8-1.2). With respect to other site-specific cancers, no significantly increased or decreased SIR were observed. Similar results were found when directly comparing women who had implants at private clinics with women who attended private clinics for other plastic surgery, with rate ratios for cancer overall, breast cancer and non-melanoma skin cancer of 1.1 (95% CI 5 0.8-1.6), 0.7 (95% CI 5 0.4-1.3) and 1.5 (95% CI 5 0.8-2.7), respectively. In conclusion, our study lends further support to the accumulating evidence that silicone breast implants are not carcinogenic. Reasons for the consistently reported deficit of breast cancer among women with breast implants remain unclear, whereas increased exposure to sunlight may explain the excess occurrence of non-melanoma skin cancer. We found no indication of delayed diagnosis of breast cancer due to the presence of breast implants. ' 2005 Wiley-Liss, Inc.Key words: breast implants; cancer incidence; risk; epidemiology; cohort studyThe carcinogenic potential of silicone has been questioned since the 1950s when silicone and other foreign materials were found to induce sarcomas in rodents.1,2 Such foreign body carcinogenesis, however, occurs in rodents with exposure to a wide array of substances, and there is no convincing evidence that a similar risk exists in humans.3,4 Silicone has also been reported to induc...

Cancer among Scandinavian women with cosmetic breast implants: A pooled long‐term follow‐up study

“…Most studies of breast cancer among women with breast implants did not have information on reproductive characteristics of the women. In a separate analysis of the Danish women with implants included in this report, the reduction in breast cancer risk persisted even after adjustment for age at first birth and number of children, 13 suggesting that reproductive factors may not have a major influence. It is also plausible that women seeking cosmetic breast implantation may be diagnosed with breast cancer during preoperative screening.…”

“…12,13 Briefly, the studies were conducted in Sweden and Denmark using essentially complete nationwide population-and health care registers, including Hospitalization Registers, Cancer Registers, Death Registers, Migration Registers, and Population Registers. Unique personal identifiers assigned to each Swedish and Danish resident encode gender and date of birth and allow record linkage among these registers with few losses to follow up.…”

“…13 This analysis based on 6,222 women with over 100,000 person-years of follow up, including women followed for more than 37 years after implantation, represents the longest follow up of women with cosmetic breast implants published to date, thus allowing us to present risk estimates for numerous additional cancer sites with too few cases to be included in the original reports.…”

Breast Implants and Anaplastic Large-Cell Lymphoma: A Danish Population-Based Cohort Study

“…The women were identified from the Danish National Registry of Patients, which contains data on all admissions to public hospitals since 1978 (3); The Danish Registry for Plastic Surgery of the Breast, which contains detailed information on 70% to 80% of all cosmetic or reconstructive breast implant procedures carried out during 1999-2009 (4), and a previously established cohort of 1,653 women who underwent breast implantation in private clinics during 1973-1995 (5). The vast majority of the breast implants were silicone-gel filled (4,5).…”

“…Lymphoma diagnoses were ascertained from the Danish Cancer Registry and The Danish Lymphoma Group Registry (4,5). Cancer diagnoses from 1978 onward are registered according to the International Classification of Diseases, version 10 (ICD-10) and the ICD for Oncology (ICD-O-1-3) for topography and morphology codes (6), thus, explaining the choice of 1978 as start of follow-up.…”