Effects of gold fiducial marker implantation on tumor control and toxicity in external beam radiotherapy of prostate cancer

Background. Evidence regarding the effects of fiducials in image-guided radiotherapy (IGRT) for tumor control and acute and late toxicity is sparse.Patients and methods. Patients with primary low-and intermediate-risk prostate cancer, 40 with and 21 without gold fiducial markers (GFM), and treated between 2010 and 2015 were retrospectively included. The decision for or against GFM implantation took anaesthetic evaluation and patient choice into account. IGRT was performed using electronic portal imaging devices. The prescribed dose was 78 Gy, with 2 Gy per fraction. Biochemical no evidence of disease (bNED) failure was defined using the Phoenix criteria. Acute and late gastrointestinal (GI) and genitourinary toxicity (GU) were assessed using the Radiation Therapy Oncology Group criteria.Results. Most patients did not receive GFM due to contraindications for anaesthesia or personal choice (60% and 25%). Regarding tumor control, no significant differences were found regarding bNED and overall and disease -specific survival (p = 0.61, p = 0.56, and p > 0.9999, respectively). No significant differences in acute and late GI (p = 0.16 and 0.64) and GU toxicity (p = 0.58 and 0.80) were observed.Conclusions. We were unable to detect significant benefits in bNED or in early or late GI and GU side effects after GFM implantation.