Is Digit Ratio Associated with the Risk of Oral Cancer?

Objectives: The risk of oral squamous cell carcinoma (OSCC) is 2.5 fold higher among males compared to females. Greater risk-taking behaviors among males is a possible explanation. While some behaviors are common among females, the risk of developing the disease remains high among males, suggesting that other factors play a role in the observed sex differences. Ratio of index and ring digits lengths (2D:4D), a proxy of intra-utero testosterone and estrogen exposure may affect a series of behavioral characteristics collectively referred to as “masculinity” or “femininity”, which in turn may influence OSCC risk.
Objective: To estimate the extent to which digit ratio is associated with an increase in OSCC risk in a population from Southern India.
Methods: We used data from a hospital-based case-control study conducted in Kozhikode, Kerala, India, between 2008 and 2012. 350 cases ( 154 females, 196 males) with newly histologically confirmed OSCC and 371 controls (167 females, 204 males) frequency matched by age and sex from two main referral hospitals were recruited. In-person interviews collected information on an array of life course exposures (e.g., sociodemographic, anthropometric, behavioral factors). We used logistic regression to estimate the odds ratios (OR) and 95% confidence intervals (CI) for the association between digit ratio and OSCC.
Results: Higher digit ratio was associated with a decreased OSCC risk in both males (OR=0.02, 95% CI 0.00–2.52) and females (OR=0.03, 95% CI 0.00–5.01). However, after adjustment for several social and behavioral factors, the association between digit ratio and OSCC disappeared (Males: OR=0.12, 95% CI −5.83–6.06. Females: OR=0.19, 95% CI 0.00–7.22).
Conclusions: The association between 2D:4D digit ratio, a proxy of intra-utero hormone exposure, and OSCC risk seems to be mediated by behavioral factors.