The risk of second malignancies following prostate cancer radiotherapy in the era of conformal radiotherapy: a statement of the Prostate Cancer Working Group of the German Society of Radiation Oncology (DEGRO)

A significant number of prostate cancer patients are long-term survivors after primary definitive therapy, and the occurrence of late side effects, such as second primary cancers, has gained interest. The aim of this editorial is to discuss the most current evidence on second primary cancers based on six retrospective studies published in 2021-2024 using large data repositories not accounting for all possible confounding factors, such as smoking or pre-existing comorbidities. Overall, prostate cancer patients treated with curative radiotherapy have an increased risk (0.7-1%) of the development of second primary cancers compared to patients treated with surgery up to 25 years after treatment. However, current evidence suggests that the implementation of intensity modulated radiation therapy is not increasing the risk of second primary cancers compared to conformal 3D-planned radiotherapy. Furthermore, increasing evidence indicates that highly conformal radiotherapy techniques may not increase the probability of second primary cancers compared to radical prostatectomy. Consequently, future studies should consider the radiotherapy technique and other confounding factors to provide a more accurate estimation of the occurrence of second primary cancers.