Table 2.
Standardized incidence ratios (SIRs) of pancreatic cancer among family members at risk: overall and stratified by family history and smoking status*
| Family history | No. of individuals | Person-years of follow-up | Observed cases | Expected cases | SIR* (95% CI) | P |
| Familial | ||||||
| Overall | 3934 | 16 760 | 29 | 4.27 | 6.79 (4.54 to 9.75) | <.001 |
| Three or more first-degree relatives | 176 | 797 | 8 | 0.47 | 17.02 (7.34 to 33.5) | <.001 |
| Two first-degree relatives | 1043 | 4477 | 7 | 1.76 | 3.97 (1.59 to 8.2) | .005 |
| One first-degree relatives | 2715 | 11 486 | 14 | 2.04 | 6.86 (3.75 to 11.04) | <.001 |
| Young-onset kindred | 705 | 3093 | 6 | 0.64 | 9.31 (3.42 to 20.28) | <.001 |
| Late-onset kindred | 3229 | 13 666 | 23 | 3.63 | 6.34 (4.02 to 9.51) | <.001 |
| Smokers | 1399 | 6125 | 14 | 1.54 | 9.09 (4.97 to 15.25) | <.001 |
| Nonsmokers | 2009 | 8553 | 12 | 1.88 | 6.38 (3.02 to 11.15) | <.001 |
| Unknown smoking history | 526 | 2083 | 3 | 0.85 | 3.53 (0.73 to 10.32) | .112 |
| Sporadic | ||||||
| Overall | 4015 | 13 876 | 8 | 3.32 | 2.41 (1.04 to 4.74) | .04 |
| Young-onset kindred | 472 | 1695 | 1 | 0.36 | 2.74 (0.05 to 15.30) | .59 |
| Late-onset kindred | 3544 | 12 181 | 7 | 2.96 | 2.36 (0.95 to 4.88) | .06 |
| Smokers | 1377 | 4681 | 4 | 1.31 | 3.04 (0.83 to 7.79) | .09 |
| Nonsmokers | 2096 | 7215 | 3 | 1.39 | 2.15 (0.45 to 8.98) | .32 |
| Unknown smoking history | 542 | 1979 | 1 | 0.62 | 1.61 (0.04 to 8.93) | .91 |
| Unrelated | ||||||
| Overall | 1091 | 4240 | 4 | 1.86 | 2.14 (0.58 to 5.49) | .23 |
| Smokers | 434 | 1407 | 2 | 0.67 | 2.98 (0.37 to 10.77) | .28 |
| Nonsmokers | 434 | 1619 | 2 | 0.65 | 3.07 (0.37 to 11.11) | .27 |
| Unknown smoking history | 223 | 1213 | 0 | 0.55 | 0 (0 to 6.71) | .94 |
*
Age-, sex-, race-, and calendar year–specific standardized incidence ratios were computed compared with data from the Surveillance, Epidemiology, and End Results database.