NEW YORK (Reuters Health) - A new study suggests that use of hair dye may increase the risk of certain types of non-Hodgkin lymphoma (NHL), a blood cancer involving the lymph nodes.
Personal use of hair dye has been suggested as a risk factor for NHL, the investigators explain, but studies exploring the association have yielded inconsistent results. To investigate the issue, Dr. Yawei Zhang from Yale University, New Haven, Connecticut and colleagues pooled data from four published "case-control" studies.
The analysis covered 4461 case patients with NHL and 5799 control subjects. Among women, 75 percent of the cases and 70 percent of the controls had ever used hair dyes. Among men, 10 percent of both cases and controls had done so.
Overall, there was a 30 percent increased risk of NHL among women (but not men) who started using hair dye before 1980, compared with nonusers, the investigators report. In this group, the risk was increased for the NHL subtypes chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and follicular lymphoma, but not other NHL subtypes.
For women who began using hair dye in 1980 or afterward, increased follicular lymphoma risk was limited to users of dark-colored dyes, Zhang and colleagues report.
The increased risk of CLL/SLL was apparent for European women, but not for US women, the report indicates, whereas the increased risk of follicular lymphoma was apparent for both European and US women.
Summing up, the investigators caution that "personal use of hair dye may play a role in the risk of NHL, particularly for follicular lymphoma and CLL/SLL. Our study also indicates that although the risk associated with personal hair-dye use was observed mainly among women who started using hair dyes before 1980, the risk was not limited to those women."
"Future studies, they note, "are needed to examine the risk of NHL by time period of hair-dye use and by genetic susceptibility."
SOURCE: American Journal of Epidemiology, June 1, 2008.
