Breast cancer detection and survival among women with cosmetic breast implants: systematic review and meta-analysis of observational studies


 

Objectives To evaluate whether the stage distribution among women diagnosed as having breast cancer differs between those who have received breast implants for cosmetic purposes and those with no implants and to evaluate whether cosmetic breast augmentation before the detection of breast cancer is a predictor of post-diagnosis survival.

Design Systematic review of observational studies with two meta-analyses.

Data sources Systematic search of the literature published before September 2012 conducted in Medline, Embase, Global health, CINAHL, IPAB, and PsycINFO.

Study selection Eligible publications were those that included women diagnosed as having breast cancer and who had had augmentation mammaplasty for cosmetic purposes.

Results The overall odds ratio of the first meta-analysis based on 12 studies was 1.26 (95% confidence interval 0.99 to 1.60; P=0.058; I2=35.6%) for a non-localized stage of breast cancer at diagnosis comparing women with implants who had breast cancer and women without implants who had breast cancer. The second meta-analysis, based on five studies, evaluated the relation between cosmetic breast implantation and survival. This meta-analysis showed reduced survival after breast cancer among women who had implants compared with those who did not (overall hazard ratio for breast cancer specific mortality 1.38, 95% confidence interval 1.08 to 1.75).

Conclusions The research published to date suggests that cosmetic breast augmentation adversely affects the survival of women who are subsequently diagnosed as having breast cancer. These findings should be interpreted with caution, as some studies included in the meta-analysis on survival did not adjust for potential confounders. Further investigations are warranted regarding diagnosis and prognosis of breast cancer among women with breast implants.

Discussion

This systematic review suggests that women with cosmetic breast implants have later stage tumors at diagnosis of breast cancer. In our second meta-analysis, the results show a higher risk of breast cancer specific mortality among women with breast cancer who have implants compared with women with breast cancer without implants. Nevertheless, the overall estimate should still be interpreted with caution because this meta-analysis included a relatively small number of studies. Of concern, three of five studies had unadjusted hazard ratios (not adjusted for age at diagnosis, or period of diagnosis) and all five studies were unadjusted for other potential confounding factors such as body mass index, which could translate into a biased estimate of the summary hazard ratio. A lack of adjustment for body mass index has previously been shown to lead to underestimation of the association between cosmetic breast implants and breast cancer mortality.18 Moreover, one study included in this meta-analysis assessed overall mortality rather than breast cancer specific mortality,39 which could have biased our summary estimate towards the null. The small number of studies and insufficient amount of follow-up time in these studies are suspected to limit statistical power to clearly evaluate survival rate patterns among augmented women. Given the limited evidence, no conclusion regarding breast cancer specific survival can be drawn and continued follow-up to further evaluate this question is particularly relevant.

Source: BMJ

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