[1] UNIV WASHINGTON, SCH MED, DEPT PATHOL, SEATTLE, WA 98195 USA
[2] FRED HUTCHINSON CANC RES CTR, DEPT PUBL HLTH SCI, SEATTLE, WA 98104 USA
[3] UNIV WASHINGTON, SCH PUBL HLTH & COMMUNITY MED, DEPT EPIDEMIOL, SEATTLE, WA 98195 USA
[4] CANC CONTROL AGCY, VANCOUVER V52 4EG, BC, CANADA