Question explored with the scientific record
Do pooled case-control studies show a link between underarm antiperspirant use and breast cancer risk?
The short version: the one real case-control study here found no link, and no pooled analysis of these studies appears in what was retrieved.
The question asks specifically about pooled case-control studies. What came back is a single population-based case-control study from Western Washington, not a pool of them. It compared 813 breast cancer cases to 793 controls and found no increase in risk from regular antiperspirant use, deodorant use, or use within an hour of shaving [1]. The odds ratios hovered around 1.0, with none reaching statistical significance [1].
| Exposure | Odds ratio | Significant? |
|---|---|---|
| Antiperspirant, ever regular use | 0.9 | No (P=0.23) |
| Deodorant, ever regular use | 1.2 | No (P=0.19) |
| Antiperspirant within 1 hr of shaving | 0.9 | No (P=0.4) |
| Deodorant within 1 hr of shaving | 1.2 | No (P=0.16) |
One study proves little on its own, and a case-control design is vulnerable to recall bias: women who already have cancer may remember their product habits differently than healthy women. The other retrieved records do not test cancer risk at all. One links product use to earlier age at diagnosis among survivors but has no control group and cannot establish cause [2]. The rest concern armpit bacteria, skin pH, and odor [3][4][5]. A 2023 review states that a causal link between aluminum and breast cancer remains unproven [6]. This retrieval cannot see any pooled analysis, so I cannot tell you what one would show.
My call: on the evidence here, no association between antiperspirant use and breast cancer risk is demonstrated, but the "pooled" part of your question is unanswered by these records. Confidence: low, because a single case-control study is thin ground and the pooled literature was not retrieved.
Sources used 6
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Antiperspirant Use and the Risk of Breast Cancer
This population-based case-control study in Western Washington found no evidence that antiperspirant or deodorant use, or use within an hour of shaving, increases breast cancer risk among women aged 20–74, regardless of shaving method.
DOI: 10.1093/jnci/94.20.1578 -
An earlier age of breast cancer diagnosis related to more frequent use of antiperspirants/deodorants and underarm shaving
This study investigates the relationship between the frequency of underarm hygiene practices, specifically antiperspirant and deodorant use, and the age of breast cancer diagnosis among female survivors, suggesting that increased usage correlates with an earlier diagnosis.
DOI: 10.1097/00008469-200312000-00006 -
The effect of habitual and experimental antiperspirant and deodorant product use on the armpit microbiome
In 17 people, stopping antiperspirant/deodorant increased culturable armpit bacteria, reapplying antiperspirant sharply reduced them, and long-term product use was associated with altered bacterial richness and composition.
DOI: 10.7717/peerj.1605 -
Axillary pH and influence of deodorants
In a 48-subject open trial, three aluminum chlorohydrate–containing deodorants significantly lowered axillary skin pH from about 6.0–6.5 to roughly 5.0–5.5 during daily use, with pH returning to baseline after wash-out, suggesting that pH regulation contributes to deodorant effi…
DOI: 10.1034/j.1600-0846.2000.006002087.x -
Deodorant effects of a supercritical hops extract: antibacterial activity against Corynebacterium xerosis and Staphylococcus epidermidis and efficacy testing of a hops/zinc ricinoleate stick in humans through the sensory evaluation of axillary deodorancy
This study evaluates the antibacterial activity of a supercritical hops extract against underarm bacteria and assesses the efficacy of a hops/zinc ricinoleate deodorant stick in reducing axillary malodor in human volunteers.
DOI: 10.1111/j.1473-2165.2009.00449.x -
Alüminyum Maruziyeti ve Sağlık
This narrative review concludes that aluminum's critical adverse effect is neurotoxicity, while causal links to Alzheimer disease and breast cancer remain unproven.
DOI: 10.38079/igusabder.1228435