Research on Hair Dyes and Prostate Cancer Risk in Taiwan

Study Overview

Researchers in Taiwan explored the potential link between hair dye usage and the risk of prostate cancer. Their findings were published in the journal BMC Cancer. Previous evidence indicated that certain compounds, specifically aromatic amines present in hair dyes, may elevate cancer risk in animal studies. However, human studies have largely failed to establish a definitive connection between hair dye usage and cancer, with some exceptions noted among hairdressers, who show an increased risk of bladder and blood cancers.

Findings from the Taiwanese Study

A case-control study conducted by Tai and colleagues in 2016 suggested a 2.15-fold increase in prostate cancer risk among southern Taiwanese men who used hair dyes. In this study, 32.1% of men with newly diagnosed prostate cancer reported using hair dyes, compared to 21.6% of matched healthy controls. The research also indicated that the likelihood of developing prostate cancer rose with age and the frequency and duration of hair dye use. However, the study concluded that hair dye usage did not impact prostate cancer survival, as determined from a second part of the study involving 608 prostate cancer cases from northern Taiwan. The authors theorized that darker hair dyes, which contain higher levels of aromatic amines, may put Asian men at a greater risk compared to lighter-haired Caucasian men.

Critiques and Concerns

A recent letter in BMC Cancer by Jiann questioned the validity of Tai’s findings, citing methodological flaws and missing data. In response, the original authors addressed these concerns in the same journal issue. One key point was the lack of assessment of cumulative exposure dosage, as hair dye usage was reported through self-administered questionnaires that did not specify brands, making it difficult to evaluate the levels of carcinogenic agents present.

Recall Bias and Data Integrity

Jiann raised concerns about missing data in the group with the highest prostate cancer risk, suggesting potential recall bias. While the authors acknowledged that self-reporting issues exist, they maintained that their results were consistent even after excluding subjects with incomplete data. They also noted that prostate cancer rates among men using hair dyes in northern Taiwan mirrored those in the control group from southern Taiwan, although the groups were not appropriately matched for age or ethnicity, and cultural perceptions of hair dye usage may differ regionally.

Historical Context and Reformulation of Hair Dyes

Another point of contention was that many participants began using hair dyes before 1980, a period when formulations were changed to eliminate known carcinogens. The authors recognized the challenges in comparing prostate cancer risks before and after this reformulation due to the small sample size of men who started dyeing their hair post-1980.

Conclusions and Future Research Directions

This correspondence underscores the complexities inherent in case-control studies and calls for cautious interpretation of their results. Although there appears to be a correlation between prostate cancer and hair dye usage among men in southern Taiwan, the evidence does not establish a causal relationship. The authors advocate for future prospective cohort studies across diverse populations to validate these observations.

References

(1) Jiann B-P. Does hair dye use really increase the risk of prostate cancer? BMC Cancer. 2017;17:724. Available from: doi: 10.1186/s12885-017-3565-z.
(2) Tai S-Y, Hsieh H-M, Huang S-P, Wu M-T. Response to “Does hair dye use really increase the risk of prostate cancer?” BMC Cancer. 2017;17:724. Available from: doi: 10.1186/s12885-017-3565-z.
(3) Tai SY, Hsieh HM, Huang SP, Wu MT. Hair dye use, regular exercise, and the risk and prognosis of prostate cancer: multicenter case–control and case-only studies. BMC Cancer. 2016;16(1):242.