BMC Cancer 2008, 8:355 http://www.biomedcentral.com/1471-2407/8/355 patients, using the Kaplan-Meier method. The endpoint was death from any cause. Follow-up ended at the end of 2006 or at loss to follow-up. The statistical significance of differences in survival probability was assessed by the log- rank test for the total survival curve. Analyses were restricted to diagnoses with at least five deaths among reg- istered cases of Turkish descent. We used the SAS statisti- cal software package (SAS, Cary, N.C.) for the analyses. Approval was obtained from the Ethics Committee of the Medical Chamber Westfalen-Lippe. Results Among 37,259 cases in the registry for whom names were available, we identified 1774 cases (4.76%) with Turkish descent as indicated by their name. Characteristics such as sex and age distribution were similar among the two com- parison groups, but loss to follow-up was somewhat higher among the cases of Turkish descent (Table 1). Slight differences in the age distribution reflect the differ- ent age distributions of the diagnoses, where Turkish cases are slightly more frequent in some diagnosis subgroups. Amongst those diagnosed until 2000 and not reported dead at the end of 2006, the percentage of cases with Turk- ish descent whose follow-up exceeded 5 years was slightly smaller (95.8%) than among the non-Turkish registry population (98.5%). Overall, loss to follow-up of these cases before the end of 2006 was higher among children with Turkish ethnicity (12.6% against 5.6% in the com- parison population). This is mostly due to former patients moving back to Turkey at a later age. The fraction of Turk- ish cases was close to the average 4.8% for most diag- noses. Notable exceptions were acute myeloid leukaemias, chronic myeloproliferative diseases, myelod- ysplastic syndrome and other myeloproliferative disease, lymphomas and reticuloendothelial neoplasms, and malignant gonadal germ cell tumours with slightly higher proportions of Turkish cases. We found rather lower pro- portions of Turkish cases for specified intracranial and Table 1: Baseline characteristics and quality of follow up in the two groups 1980–2005 Number of cases male sex Age at diagnosis <1 year 1–<5 years 5–<10 years 10–<15 years Year of diagnosis 1980–87 1988–95 1996–2005 Deaths by 31.12.2006 Follow-up by period of diagnosis 1980–1995 Alive, at least 10 years f/u Alive, lost to f/u 1980–2000 Alive, at least 5 years f/u Alive, lost to f/u 1996–2000 Alive, at least 5 years f/u Alive, lost to f/u N = number, f/u = follow-up Median length of follow-up of patients still alive (range) in years Turkish descent N (%) 1774 1042 (58.7) 167 (9.4) 682 (38.4) 503 (28.4) 422 (23.8) 369 (20.8) 477 (26.9) 928 (52.3) 7.1 (0–28) 456 (25.7) 507 (92.0) 93 (16.9) 879 (95.8) 116 (12.6) 357 (97.3) 23 (6.3) Not Turkish N (%) 35,485 19,822 (55.9) 3555 (10.0) 12,914 (36.4) 9516 (26.8) 9500 (26.8) 7576 (21.4) 11,366 (32.0) 16,543 (46.6) 8.4 (0–28) 8737 (24.6) 12,613 (96.7) 910 (7.0) 19,549 (98.5) 1104 (5.6) 6725 (98.8) 194 (2.9) Page 3 of 7 (page number not for citation purposes)