Recent meta-analyses have examined the association between the TP53 arginine/proline polymorphism at codon 72 (Arg72Pro) and the risk of breast cancer, 1 lung cancer, 2 gastric cancer, 3 and cervical cancer. 4 A critical reanalysis of the most recent meta-analyses was performed to examine whether the effect of Arg72Pro is modified by latitude.
Latitude was assigned to all 108 studies that were included in the 4 aforementioned meta-analyses. 1-4 A metaregression was performed to determine whether latitude may modify the effect of the C allele (dominant model). Latitude was treated as a binary variable (0, latitude less than or equal to the median; 1, latitude greater than the median). The analysis was performed using STATA 10.0 software (Stata Corporation, College Station, Tex).
The median latitude for the meta-analyses was 40.78 in breast cancer, 37.06 in lung cancer, 33.43 in gastric cancer, and 37.55 in cervical cancer. Concerning breast cancer in Caucasians (32 studies), greater latitude was associated with a more limited protective effect of the G (Arg) allele (exponentiated coefficient, 1.75, 95% confidence interval [CI], 1.22-2.49; P ΒΌ .003). No significant association was detected in Asians.
Regarding lung cancer, greater latitude tended to intensify associations between the C (Pro) allele and cancer in Caucasians at a borderline level (16 studies; exponentiated coefficient, 1.39; 95% CI, 0.93-2.07; P ΒΌ .097). Such an effect was not observed for either Asian or mixed populations. Concerning gastric cancer and cervical cancer, no significant effects were demonstrated.