Abstract: Objective To  investigate the risk factors for secondary primary malignancies (SPM) after radical prostatectomy of non-metastatic prostate cancer. Methods The clinical data of patients diagnosed with T1－4N0M0 prostate cancer from 2010 to 2015 were screened from the Surveillance, Epidemiology, and End Results (SEER) database. Patients were divided into operation group, operation plus radiotherapy group, and operation plus chemotherapy group according to the treatment methods. The incidence and common sites of SPM under different treatment methods were compared. Results A total of 243 094 patients were included in this study, and 19 344 patients (8.0%) developed SPM. The median time for SPM was 36 months.The top five most common organs of SPM were lungs and bronchus, bladder, skin, kidney and renal pelvis, and colorectal. Logistic regression analysis showed that race, age, chemotherapy and radiotherapy were independent factors influencing SPM. The incidence of SPM in the surgery plus chemotherapy group (19.7%) was significantly higher than that in operation group (6.4%) and operation plus radiotherapy group (8.3%) (P<0.05), but  no significant difference of SPM involved system among three group. The mainly four involved systems were digestive system, urinary system, immune system and respiratory system. Conclusion The incidence of SPM is increased in patients receiving surgery plus radiotherapy or surgery plus chemotherapy, especially in the latter group.The SPM distributed at similar sites, but more likely occurred in the digestive system in patients receiving surgery plus radiotherapy. For prostate cancer patients with different treatment methods, attention should be paid to the occurrence of SPM in addition to the vigilance of recurrence and metastasis of prostate cancer.

Key words: prostate cancer, secondary primary malignancies, incidence of disease, SEER database