Incidence of Second Primary Malignancies in Patients with Castration-Resistant Prostate Cancer: An Observational Retrospective Cohort Study in the United States
Table 1
Cohort selection.
Reason for exclusion
No. of patients ()
Remaining sample
Initial sample of prostate cancer cases from SEER-Medicare data
564,491 (100)
564,491
No record of surgical or biologic castration
383,713 (67.98)
180,778
No record of second-line systemic therapy† after castration date
168,388 (29.83)
12,390
Castration was on or before prostate cancer diagnosis date
376 (0.07)
12,014
Diagnosis of any cancer other than prostate cancer or nonmelanoma skin cancer on or before potential cohort entry date
5,543 (0.98)
6,471
Diagnostic code for exclusionary metastases (197X or 198X with exception of 198.2-skin or 198.5-bone) on or before potential cohort entry date
1,767 (0.31)
4,704
Not aged at least 65 years on potential cohort entry date
246 (0.04)
4,458
Not continuously enrolled in both Parts A and B Medicare coverage between the earlier of (1) 12 months before cohort entry or (2) the month of prostate cancer diagnosis and cohort entry date
1,293 (0.23)
3,165
Enrolled in HMO either (1) in year before potential cohort entry date, or (2) at some time between diagnosis date of initial prostate cancer identified in SEER and potential cohort entry date
931 (0.16)
2,234
SEER, Surveillance, Epidemiology, and End Results program of the US National Cancer Institute; HMO, health maintenance organization. † Abiraterone, cabazitaxel, docetaxel, enzalutamide, mitoxantrone, or sipuleucel-T.
