Table 1.

Mean age at first cancer onset in different generations of LFS families with 1–4 documented generations

	Records of families with N generations with available data
Generation	431, n = 4	797, n = 3	570, n = 2	169, n = 1	P (t test)
1	51.8 ± 15.4	—	—	—	—
2	45.6 ± 15.3	45.7 ± 16.2	—	—	P(4-3) = n.s.
3	33.5 ± 12.5	36.9 ± 16.8	35.9 ± 14.5	—	P(4-2) = n.s.
4	(10.0 ± 8.0)	20.1 ± 15.1	22.5 ± 18.9	21.2 ± 23.9	P(3-1) = n.s.
P (t test)	P(1-3) < 0.001	P(1-3) < 0.032	P(1-2) = n.s.	—	—

P value for significance of difference in mean age of cancer onset between the first and last generation of multigeneration families are listed in the bottom row, and between comparable generations across different generation families are listed in the rightmost column. The mean age for generation 4 is in parenthesis because the median age of this generation is 11.5 years, so is excluded from analysis. n.s., nonsignificant.