Introduction: Radiotherapeutic treatment of prostate cancer has been validated in terms of efficacy, but its relationship with the occurrence of second pelvic primary malignancy and the relevance of radio-induced toxicity is still under debate. This study analyses the occurrence of second pelvic primary malignancy as well as morbidity secondary to radiotherapy treatment in patients treated for prostate cancer.
Material and methods: Retrospective consecutive descriptive study of 317 patients who received radiotherapy treatment for prostate cancer between 2007 and 2017. Predictor variables, side effects and the appearance of second pelvic primary malignancy during a maximum follow-up of 10 years were collected. We analyse whether there is a significant relationship in the appearance of second pelvic primary malignancy and describe the clinical toxicity presented by the patients.
Results: The median age was 62.27 years and the most commonly employed treatment modality was brachytherapy with IMRT (60%). 17 patients (5.4%) developed a second pelvic primary malignancy, with a median time to onset of 58 and 25 months for bladder and colon tumours, respectively. Local recurrence and mortality rates are 8% and 7%, respectively. Statistically significant association is demonstrated for the occurrence of second pelvic primary malignancy and for chronic radioinduced toxicity according to type of radiotherapy χ2 (4) = 16.34; p = 0.003 and χ2 (1) = 6.47; p = 0.011 respectively.
Conclusions: In our series, the occurrence of a second pelvic primary malignancy is statistically associated with the modality of radiotherapy administered and occurrence of chronic adverse effects.
Keywords: bladder and rectum; prostate cancer; radiotherapy; second malignancies.