[1] IST NAZL TUMORI, I-20133 MILAN, ITALY
[2] NATL PUBL HLTH INST, SF-00280 HELSINKI, FINLAND
[3] INT AGCY RES CANC, ANALYT EPIDEMIOL UNIT, F-69372 LYON, FRANCE
[4] DEUTSCH KREBSFORSCHUNGSZENTRUM, W-6900 HEIDELBERG 1, GERMANY
[5] WEXHAM PK HOSP, LADY SOBELL GASTROINTESTINAL UNIT, ECP HEADQUARTERS, SLOUGH SL2 4HL, BERKS, ENGLAND