Association between the second- and fourth-digit ratio and oral squamous cell carcinoma

Using an established proxy measure of intra-utero testosterone and estrogen levels-the ratio of second- and fourth-digit lengths-we estimated its association with the oral cancer risk among a population from Southern India.

In a hospital-based case-control study, incident oral cancer cases (N = 350) and non-cancer controls (N = 371), frequency-matched by age and sex, were recruited from two major referral hospitals in Kerala, India. Structured interviews collected information on several domains of exposure via detailed life course questionnaires. Digit lengths were measured using a ruler in a standardized manner. Unconditional logistic regression was performed to estimate the odds ratios and 95% confidence intervals.

Second- and fourth-digit ratio lower than 1, which indicates relatively higher intra-utero level of testosterone and lower intra-utero level of estrogen, was associated with higher oral cancer risk (OR = 1.60, 95% CI: 1.02-2.52), after accounting for several confounders.

Our findings suggest that intra-utero hormonal levels measured by second- and fourth-digit ratio are associated with oral cancer risk. Further studies in different population should confirm these results.