Table 1 Clinical characteristics of the analytical cohort. Clinical characteristics of patients with a single primary cancer and patients with multiple primary cancers
Clinical variable | Singleprimary cancer (n = 107,269, 99.37%) | Multipleprimary cancers (n = 1785, 1.63%) | Total (n = 109,054) | RR (95% CI) | P |
|---|---|---|---|---|---|
Sex |  |  |  | 0.94 (0.85–1.03) | 0.164 |
 Male | 45,834 (42.7%) | 792 (44.4%) | 46,626 (42.8%) |  |  |
 Female | 61,435 (57.3%) | 993 (55.6%) | 62,428 (57.2%) |  |  |
Age at 1st diagnosis |  |  |  | 1.01 (1.01–1.02) | <  0.001 |
 Mean (SD) | 57.2 (14.517) | 60.2 (13.2) | 57.2 (14.5) |  |  |
 Range | 18.0–106.0 | 18.0–103.0 | 18.0–106.0 |  |  |