Finger length ratio and prostate cancer risk queried
MedWire News: There is no significant association between the ratio of the lengths of men's index and ring fingers (2D:4D) and their prostate cancer risk, show Australian study results.
As reported by MedWire News, research has previously shown that men whose index fingers are longer than their ring fingers are less likely to develop the disease compared with men whose ring fingers are longer.
However: "Our analysis does not confirm the strong inverse association between 2D:4D and risk of prostate cancer previously reported," write David Muller (The University of Melbourne, Victoria) and colleagues in the British Journal of Cancer.
The team used data for men who participated in the Melbourne Collaborative Cohort Study (1990-1994), of whom 6287 were followed-up between 2003 and 2009 and had a photocopy of their hands taken. The men's index and ring finger lengths were measured using the photocopies and 2D:4D was calculated.
A total of 686 incident cases of prostate cancer were recorded among 6258 men who had available follow-up data. Men with a diagnosis of the disease were younger on average than those who were not, at 54 versus 59 years old.
Overall, there was no association between either left or right 2D:4D and prostate cancer risk, report Muller et al. They found some indication that one standard deviation higher 2D:4D in either hand was associated with lower early-onset prostate cancer risk, however, with a nonsignificant approximate 20% reduced risk for men aged 55 years.
Similarly, note the researchers, the risk for prostate cancer among men older than 80 years was marginally reduced with higher 2D:4D.
The team then divided results into those for men aged under and over 60 years and found that higher 2D:4D may be associated with reduced prostate cancer risk, reducing it by 9% and 12% for left and right hands, respectively. Again, this was nonsignificant.
"Further research is required to clarify any association between 2D:4D and prostate cancer, especially for younger men," conclude Muller and co-investigators.
"The explanation that such risk may be driven by an underlying relationship with pre-natal hormone levels remains speculative, but would be in keeping with current thinking on the etiology of prostate cancer," they add.
In an accompanying comment on the research, M Cheema and A Sharif (Norfolk and Norwich University Hospital NHS Trust and GPTVS, West Midlands, UK) warned that it is not possible to conclude that adult proportions reflect prenatal hormone levels.
"Even with that evidence, the difference in digit length in adults may well reflect environmental factors or even difference in dexterity or pattern of hand usage amongst the individuals," they said.
By Sarah Guy