Secondary cancers during the radiotherapy of prostate cancer: a review article

Prostate cancer is the most common and second leading cause of death among men in the world. Nowadays, radiotherapy has been known as one of the most affecting methods for prostate cancer treatment. Nevertheless, radiotherapy is accompanied by the concern of developing secondary cancers by the scattered radiation to the neighbor  organs at risk. Several studies have shown that secondary cancers after the radiotherapy of prostate cancer treatment, occur in tissues such as the bladder and rectum which have been exposed to direct or indirect radiations. Therefore, this review study aimed to evaluate the influencing factors for developing secondary cancers after the radiotherapy of prostate cancer. To access the previously validated published studies, Persian and English keywords such as prostate cancer, secondary cancers, radiotherapy and organs at risk have been searched in ISID, Google Scholar, Science Direct, PubMed, and World Health Organization, between 1997 and 2021. Totally 246 pieces of literature have been selected which finally, by ignoring the similar and overlapping studies, only 40 studies were reviewed. In the present study, the most affecting factors for developing secondary malignancies including the anatomical status changes, dose variations, smoking and the impact of the various treatment techniques, have been studied. The results of the reviewed studies showed a reduction of secondary cancer risks with performing the modern modalities such as proton therapy to treat prostate cancer. Moreover, organ movements and anatomical status changes which vary from one patient to others, have been reported to make a significant difference in the relative risk of secondary cancers. It has been shown that smoking may increase the risk of secondary cancers after the radiotherapy of prostate cancer, so radiotherapy and smoking may cause genetic mutations. Despite the advantages of radiotherapy for prostate cancer treatment, developing secondary cancers after the radiotherapy should not be ignored. Assessments of the affecting factors for secondary cancers after the radiotherapy of prostate cancer require social and comprehensive studies which can result in an accurate modality with fewer side effects.