Heritability of cervical tumours

Development of cervical cancer is strongly associated with genital infection of oncogenic types of human papillomavirus (HPV). However, the majority of women infected with HPV never develop cancer; thus, additional factors appear to be necessary. The relative importance of genetic and environmental factors to the development of cervical tumours is not known. Therefore, we have estimated the heritability of liability to this disease. The Swedish Cancer Register and the National Family Register were used to identify biological and adoptive mothers and full, half- and adoptive sisters of cases with cervical tumours, as well as age-matched controls. Tetrachoric correlations were calculated and model fitting techniques used to estimate the relative importance of shared genes and shared familial environment. Shared genes (heritability) explain 27% (95% CI 26%-29%) of the total variation in liability to the disease. A significant effect of shared familial environment was seen among sisters but not among mother/daughter relations. Sister-specific shared environment accounts for 2% (95% CI 1%-4%) of the variance. Our results indicate that development of cervical tumours depends, to a significant extent, on inherited genetic factors. Genetic predisposing factors may influence the likelihood of, sensitivity to or persistence of HPV infection, as well as the rate of tumour development.