Skin lighteners and hair relaxers as risk factors for breast cancer: results from the Ghana breast health study

Authors: Brinton, LA, Figueroa, JD, et. al.
Source: Carcinogenesis, 2018, Vol. 39, No. 4, 571-579
academic.oup.com/carcin/article/39/4/571/4792875

Rates of breast cancer are rising in Africa.  It is expected that the number of cases will double between 2012 and 2030.  Many researchers are trying to understand the trend.  While decreasing parity, advanced age at first childbirth and increasing body mass are rising trends in Africa and suspected to be causes for the breast cancer rates (as they are in other nations), other factors may play roles.

Skin lighteners and hair relaxers are very commonly used among women of African descent.  Ingredients in both products, including phthalates, are presumed to have some biologic activity as they are absorbed into the skin and enter a woman’s bloodstream (particularly following scalp burns from relaxers).  Investigators questioned whether or not these substances influence a woman’s development of breast cancer.

The Ghana Breast Health Study is a population-based study in two large Ghanaian cities (Accra and Kumasi).  Women aged 18-74 were recruited for this study upon presenting with a breast mass that was recommended for biopsy.  Participants were interviewed about their use of skin lighteners and hair relaxers.

There were about 1130 women with breast cancer and 2100 controls in this study.  Women with breast cancer tended to be older (50 vs. 46 years).  They had higher levels of education, family histories of breast cancer, larger body mass, later age at menarche (first period) and later age at first childbirth.

The use of skin lighteners was more common among women aged 45 and older, women with less education and women who had their first children at young ages.  The use of skin lighteners was unrelated to breast cancer risk.

Hair relaxer was used most commonly among women ages 35-54.  It was associated with a 58% increased likelihood of developing breast cancer.  The greatest difference was in Accra.  There was little effect of hair relaxers upon risk in Kumasi.  For both cities, former users had greater breast cancer risk compared to current users.  The researchers questioned the possibility that women who used relaxers in the past used products that were less monitored.  Therefore, they may have been exposed to contaminates and/or more toxic substances that promoted breast cancer.

Surprisingly, lye relaxers did not affect breast cancer risk, while non-lye relaxers did.

This study did not definitively find links between skin lighteners and breast cancer.  However, it raised questions about the association between hair straighteners and the disease.  While other factors (such as body mass and family history) play roles in the development of breast cancer, the researchers maintain that there could be valid connections between the substances in hair straighteners and the biology of breast cancer.  They recommend continued study of both hair relaxers and skin lighteners among women of African descent with breast cancer to definitively determine if they play roles in the development of the disease.