Aluminum is associated with genotoxicity and estrogenic activity and has been linked to DNA damage and genomic instability in breast tissue, especially in the outer regions of the breast, leading to concern that antiperspirant use may be associated with the development of breast cancer (BC). The chlorohydrate salt has been found to increase estrogen receptor alpha protein, which is a regulator of BC development and progression. Further, it is thought that aluminum alters the breast microenvironment, leading to oxidative damage and inflammation. Additionally, other ingredients found in antiperspirants, such as parabens and phthalates, are endocrine disrupters. Any break in the skin during shaving may enhance absorption of these substances.

To examine the possible association between underarm antiperspirant or deodorant use and the risk of BC, investigators conducted a meta-analysis of observational epidemiological studies. A literature review was performed using PubMed, Embase, Scopus, and Web of Science from inception until May 1, 2024, to determine the risk of underarm cosmetic use and BC. The search was limited to case-control studies reporting outcome measures with odds ratios and 95% CIs or the ability to calculate these statistical measures.

Methodological quality was assessed using the Newcastle-Ottawa Scale. Heterogeneity and risk of bias were also evaluated.

The authors included seven articles in the final analysis, which include 3,745 participants (age range: 15-85 years). Of these participants, 1,909 had BC and 1,836 participants served as control. While publication year ranged from 2002–2021, the enrollment period spanned from 1992–2018. Over 40% (42.9%) of studies originated in Iran with the rest of the studies (one each) conducted in Australia, Iraq, Turkey, and the United States.

The researchers found that the use of antiperspirants/deodorants was not associated with an increased risk of BC (odds ratio 0.96; 95% CI, 0.78-1.17; I2 [a measure of heterogeneity] 60%). However, the authors caution that only three out of the seven studies were of high quality, and six of the seven studies relied on self-reporting. There was no evidence of publication bias.

The authors stated that although aluminum-based products possess estrogenic effects, mutagenic effects are only seen at higher concentrations than what occur with typical use. The American Cancer Society has also asserted that at this point there is no clear link between antiperspirants containing aluminum and BC.

Nonetheless, the investigators cautioned that their data may have been compromised by the small number of studies, issues with quality, lack of information on the duration of use, and the inherent bias of case-control studies.

For those seeking an alternative to aluminum-based antiperspirants/deodorants, the nonprofit organization, Environmental Working Group, offers a database called Skin Deep that can be searched for alternative aluminum-free products.

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