Image-guided salvage radiotherapy improves outcomes in patients with prostate cancer

1. 3-year event-free survival rates were significantly greater in the 18F-fluciclovine-PET group compared to conventional imaging.

2. Adverse reactions and toxicity levels were similar between the two groups.

Evidence Rating Level: 1 (Excellent)

Study Rundown: In patients with prostate cancer, prostatectomies are often followed with adjuvant or salvage radiotherapy. Postprostatectomy radiotherapy has conventionally been guided with a bone scan plus CT or MRI, but the diagnostic yield of these modalities has been questioned. The value added by nuclear image studies in addition to conventional imaging modalities, such as MRI and CT, has been of significant conversation. This study sought to assess the practical value added by the 18F-fluciclovine-PET/CT guided imaging in salvage radiotherapy treatment of prostate cancer. This randomized control trial found a significant improvement in event-free survival among those who received 18F-fluciclovine-PET imaging in addition to conventional imaging to guide radiotherapy. This was attributed to superior localization of the malignant lesions to be targeted by radiotherapy techniques. The study is most strengthened by its randomized control structure which better allows one to suggest that the observed differences were attributable to the additional imaging. Nevertheless, the most significant weaknesses involve the subjective interpretation of the imaging along with the variable subsequent use of the imaging in the development of radiotherapy.

Click to read the study in the Lancet

Relevant Reading: Postoperative radiotherapy after radical prostatectomy for high-risk prostate cancer: long-term results of a randomised controlled trial (EORTC trial 22911)

In-Depth [randomized controlled trial]: This single center randomized control trial included patients with prostate adenocarcinoma with detectable PSA after prostatectomy and no metastasis. Patients with previous pelvic radiotherapy, medically-ineligible for radiotherapy or previous malignancy within the last 3 years were considered ineligible. Patients were randomized between the treatment group (n=83) and the control group (n=82). The treatment entailed 18F-­fluciclovine­-PET/CT imaging in addition to conventional imaging with either CT and MRI; the subsequent radiotherapy decisions were determined by 18F­-fluciclovine-­PET, MRI, or CT imaging findings for each patient. Subsequent to therapy, the patients continued to receive appropriate medical care such as androgen-deprivation therapy. Patients assessed at 1-, 6-, 12-, 18-, 24-, 30-, and 36-month intervals after radiotherapy treatment with PSA levels and physical examinations. Univariable determined that the 3-year event-free survival was 63.0% (95% CI 49.2-74.0) and 75.5% (95% CI 62.5-84.6) in the control and treatment groups, respectively (p= 0.003). Multivariable analyses also showed that the 18F­fluciclovine­PET group was associated with improved event-free survival (hazard ratio 2.04 [95% CI 1.06–3.93], p=0.0327). Similar trends were replicated in PSA analyses where 18F­-fluciclovine-­PET/CT was linked to decreased PSA levels after radiotherapy treatment.

Image: PD

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