Table 4. Difference in Age at Diagnosis Among Monozygotic and Dizygotic Pairs of Twins for Specific Types of Cancer.
| No. Concordant Pairsa | Age Difference at Diagnosis, Median (95% CI), y | P Valueb | |||
|---|---|---|---|---|---|
| Monozygotic | Dizygotic | Monozygotic | Dizygotic | ||
| Overall cancer | 1383 | 1933 | 8.0 (0.4-22.8) | 9.3 (0.3-33.9) | .002 |
| Head and neck | 5 | 6 | 6.8 (3.3-12.3) | 10.1 (3.5-17.8) | .65 |
| Stomach | 14 | 15 | 10.3 (5.2-15.4) | 14.2 (10.0-18.4) | .65 |
| Colon | 30 | 31 | 8.3 (5.8-11.1) | 6.1 (3.8-11.7) | .62 |
| Rectum, anus | 14 | 13 | 10.3 (6.0-15.3) | 5.3 (2.7-11.6) | .44 |
| Lung | 50 | 74 | 7.8 (6.1-9.5) | 7.7 (5.4-9.4) | .94 |
| Skin | |||||
| Melanoma | 1 | 6 | 8.9 (7.5-21.8) | 15.8 (3.4-23.6) | .72 |
| Nonmelanoma | 16 | 10 | 6.1 (3.5-11.9) | 7.4 (2.4-7.7) | .66 |
| Breast | 124 | 141 | 9.3 (6.9-12.0) | 10.5 (9.1-12.2) | .55 |
| Corpus uteri | 9 | 6 | 12.4 (6.7-17.2) | 9.3 (3.6-10.5) | .72 |
| Prostate | 197 | 148 | 3.7 (4.4-6.1) | 6.1 (4.6-7.9) | .008 |
| Bladder | 18 | 13 | 7.1 (4.1-9.9) | 14.3 (7.2-20.5) | .31 |
a
The numbers refer to the number of twin pairs not the individual twins.
b
For difference in median ages between twin types (monozygotic vs dizygotic).