Incidence of Second Primary Malignancies in Patients with Castration-Resistant Prostate Cancer: An Observational Retrospective Cohort Study in the United States

Table 5

Incidence rates of second primary cancer, per 100 person-years.

Case identification	Patients	Person-years	Cases	Rate; (95  CI)
SEER and Medicare	2,234	2,922	172	5.9 (5.0-6.8)
Age at cohort entry, years
65-69	297	551	30	5.4 (3.7-7.8)
70-74	625	920	63	6.8 (5.3-8.8)
75-79	595	747	37	5.0 (3.5-6.8)
> 80^†	717	704	42	6.0 (4.3-8.1)
SEER only	1,664	2,055	20	0.97 (0.59-1.5)

CI, confidence interval; SEER, Surveillance, Epidemiology, and End Results program of the United States National Cancer Institute.
^† Categories were combined to avoid reporting a count of less than 11.