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「ヘアカラー」や「ストレートパーマ」で乳がん発症リスクが増加の可能性-米NIH

姉妹に乳がん罹患者がいる女性約5万人の調査から

アメリカ国立衛生研究所NIH)は12月4日、乳がんの発症リスクを高める要因として、ストレートパーマや髪の毛のカラーリングが挙げられることを見出したと発表した。この研究はNIHのEnvironment and Cancer Epidemiology Groupが行ったもの。研究成果は、「International Journal of Cancer」に掲載されている。

ヘアカラーとがん発症の因果関係については、長年研究されてきたが、未だ解明されていなかった。今回検証に用いたデータは、NIHが主導した過去の調査「SISTER STUDY」で得られたもの。この調査は2003~2009年に米国とプエルトリコで行われ、35~74歳までの女性で、乳がんを患っている姉妹がいる4万6,709人を対象としたものだった。

ヘアカラー、ストレートパーマを高頻度で施す女性は発症リスク増

解析の結果、ヘアカラーを行う頻度が高い女性は、ヘアカラーを行わない女性と比較して、乳がんの発症リスクが9%高いことがわかった。詳細に分析すると、アフリカ系アメリカ人の女性で5~8週の間隔でヘアカラーを行っていたグループでは60%も発症リスクが高いことが判明。同様に白人系では8%上昇していた。一方、ヘアカラーの頻度が少ない、もしくは部分染めによる影響は大きくないという。

また、興味深いことに、化学的薬剤を用いたストレートパーマと乳がん発症に関連があることも判明した。ストレートパーマを5~8週間隔で施した女性では、乳がん発症リスクが30%高かった。また、アフリカ系アメリカ人と白人の女性では、ストレートパーマによる影響は同程度のものだったが、ストレートパーマを施す頻度はアフリカ系アメリカ人の方が高かった。

今回、統計的には関係性が示されたが、他の調査とも照らし合わせてさらに検討する必要がある。「さまざまな乳がんの発症要因がある中で、女性はヘアカラーやストレートパーマをすぐにやめるべきかというと、そこまでは言えないが、乳がん発症リスクを低減させるために控えるようにるすことは有効であると推測される」と、研究グループは述べている。(QLifePro編集部

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関連リンク|National Institutes of Health News Releases

Permanent hair dye and straighteners may increase breast cancer risk|永久染毛料や縮毛矯正は乳がんのリスクを高める可能性がある

Scientists at the National Institutes of Health found that women who use permanent hair dye and chemical hair straighteners have a higher risk of developing breast cancer than women who don’t use these products. The study published online Dec. 4 in the International Journal of Cancer and suggests that breast cancer risk increased with more frequent use of these chemical hair products.

Using data from 46,709 women in the Sister Study, researchers at the National Institute of Environmental Health Sciences (NIEHS), part of NIH, found that women who regularly used permanent hair dye in the year prior to enrolling in the study were 9% more likely than women who didn’t use hair dye to develop breast cancer. Among African American women, using permanent dyes every five to eight weeks or more was associated with a 60% increased risk of breast cancer as compared with an 8% increased risk for white women. The research team found little to no increase in breast cancer risk for semi-permanent or temporary dye use.

“Researchers have been studying the possible link between hair dye and cancer for a long time, but results have been inconsistent,” said corresponding author Alexandra White, Ph.D., head of the NIEHS Environment and Cancer Epidemiology Group. “In our study, we see a higher breast cancer risk associated with hair dye use, and the effect is stronger in African American women, particularly those who are frequent users. “

An intriguing finding was the association between the use of chemical hair straighteners and breast cancer. Dr. White and colleagues found that women who used hair straighteners at least every five to eight weeks were about 30% more likely to develop breast cancer. While the association between straightener use and breast cancer was similar in African American and white women, straightener use was much more common among African American women.

Co-author Dale Sandler, Ph.D., chief of the NIEHS Epidemiology Branch, cautioned that although there is some prior evidence to support the association with chemical straighteners, these results need to be replicated in other studies.

When asked if women should stop dyeing or straightening their hair, Sandler said, “We are exposed to many things that could potentially contribute to breast cancer, and it is unlikely that any single factor explains a woman’s risk. While it is too early to make a firm recommendation, avoiding these chemicals might be one more thing women can do to reduce their risk of breast cancer.”

About the National Institute of Environmental Health Sciences (NIEHS): NIEHS supports research to understand the effects of the environment on human health and is part of the National Institutes of Health. For more information on NIEHS or environmental health topics, visit https://www.niehs.nih.gov/ or subscribe to a news list.

About the National Institutes of Health (NIH): NIH, the nation’s medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.

National Institutes of Health

Therapeutic potential of Lawsonia inermis Linn: a comprehensive overview|ヘナ の治療的可能性: 包括的な概要

Lawsonia inermis Linn, commonly known as henna, is a member of the Lythraceae family and has been found to contain a variety of compounds with both industrial and medicinal applications in its stem, bark, roots, flowers, and seeds. This report provides a comprehensive review of the bioactive components, pharmacological activities, pharmacokinetics, and pharmacological side effects of Lawsonia inermis. Relevant materials were gathered from Google Scholar, PubMed, Scopus, and Web of Science and reviewed for important properties and updates about the plant. Lawsonia inermis contains a variety of bioactive compounds, including flavonoids, coumarins, triterpenoids, steroids, xanthones, polyphenols, fatty acids, alkaloids, quinones, tannins, leucocyandin, epicatechin, catechin, and quercetin. The plant is been traditionally used to treat numerous conditions, including ulcers, bronchitis, lumbago, hemicrania, leukoderma, scabies, boils, ophthalmic disorders, hair loss, and jaundice. It has also been found to possess a range of pharmacological activities, including antioxidant, anti-inflammatory, analgesic, antiparasitic, hepatoprotective, antifungal, antitumor, wound healing, and hypoglycemic effects. The potential of Lawsonia inermis for various biological applications is promising, and further studies are needed to fully explore its therapeutic benefits for various diseases of public health. Concern advances in drug development could enable the characterization of various bioactive constituents and facilitate their development and application for the benefit of humanity.

National Library of Medicine