Page 40 - 20dynamics of cancer

AGE OF CANCER INCIDENCE 25

%PP 6IXMRSFPEWXSQE YRMPEXIVEP 8IWXMGYPEV

z
z z
2IYVSFPEWXSQE 6IXMRSFPEWXSQE FMPEXIVEP 3WXISWEVGSQE

%GGIPIVEXMSR

z
z z
;MPQW ,ITEXMG 'EVGMRSQE

z
z z
Figure 2.5 Age-specific acceleration of childhood cancers. Calculated as the
slopes of the fitted splines in Figure 2.4.

accelerations, whereas carcinomas have increasing acceleration in the
teen years.

2.4 Inheritance

Genetically predisposed individuals develop cancer earlier in life than
do normal individuals. Ideally, we would compare age-specific inci-
dences for different genotypes to measure how genes affect the onset
of cancer.
Three problems arise in analyzing age-specific incidence curves for
particular genotypes. First, currently available sample sizes tend to be
small, so that we get only a rough idea of the age distribution of cases