18F-DCFPyL PET/CT for primary staging in 160 high-risk prostate cancer patients; metastasis detection rate, influence on clinical management and preliminary results of treatment efficacy

PURPOSE

Prostate-specific membrane antigen (PSMA) PET/CT shows better diagnostic performance for detection of lymph node and bone metastases as compared to conventional imaging. Studies of PSMA PET/CT in primary staging comprise highly selected patient cohorts. This study evaluates ¹⁸F-DCFPyL PET/CT as first-line imaging modality for primary staging of high-risk prostate cancer.

MATERIAL

From February 2018 until April 2019, all patients with high-risk prostate cancer received ¹⁸F-DCFPyL PET/CT for staging of prostate cancer. Baseline characteristics, findings at ¹⁸F-DCFPyL PET/CT, number and type of required additional diagnostic procedures, findings at additional diagnostic procedures, and effects of therapy on PSA levels for all patients treated with curative intent were collected and evaluated.

RESULTS

One hundred-sixty patients were included in the study of which 90 (56%) had evidence of metastasized disease (N1, M1a, M1b and, M1c in 49%, 28%, 31%, and 3% respectively). Additional diagnostic imaging was needed in 2/160 patients (1%) because of equivocal findings on ¹⁸F-DCFPyL PET/CT. Eighty-one patients had evidence of PSMA-positive lymph node metastases, of whom 39 (48%) had no enlarged lymph nodes on CT; ¹⁸F-DCFPyL PET detected additional metastatic lymph nodes in 41/42 patients that had evidence of lymph node metastases on CT. ¹⁸F-DCFPyL PET altered patients' management in 17% of patients.

CONCLUSION

¹⁸F-DCFPyL PET/CT can be used as first-line imaging modality for therapy selection in patients with primary high-risk prostate cancer, without need for further diagnostic imaging procedures in the majority of patients.

[Guideline 'Precautionary measures for contrast media containing iodine']

Annually, 0.5-1 million injections of contrast media containing iodine are administered in the Netherlands. Almost all contrast media nowadays are low-osmolar and nonionic. Nevertheless, the development ofcontrast-induced nephropathy is still a relevant clinical problem. Through an initiative by the Radiological Society of the Netherlands and with aid of the Dutch Institute for Healthcare Improvement (CBO), a guideline was conceived for the intravascular use of iodine-containing contrast media, based on recent scientific literature. The guideline defines the risk factors for contrast-induced nephropathy. One of the major risk factors is an impaired renal function. It is important to measure the glomerular filtration rate (GFR) in patients with a possible impaired kidney function, preferably by using the 'Modification of diet in renal disease' (MDRD)-study formula. The key measures for avoidance of contrast nephropathy are: limiting the amount of contrast agent used and to assure good hydration, by infusion of sodium chloride 0.9% 12-16 ml/kg body weight, both prior to and after contrast infusion. If time is limited, intravenous administration of sodium bicarbonate is an option. The guideline recommends discontinuation of metformin use from the day of contrast injection, if the GFR < 60 ml/min/1.73 m2, and to restart metformin 2 days following contrast infusion providing the GFR has not significantly deteriorated. Only in the case of previous moderate or severe adverse reactions to contrast media, prophylaxis with corticosteroids and antihistamines is recommended. Iodine allergy or an atopic condition is not a contraindication for the use of iodine-containing contrast media, and no prophylaxis is required. No specific measures are indicated in case of hyperthyroidism, acute pancreatitis, or phaeochromocytoma. Injection of contrast media is not contraindicated in case of pregnancy or lactation.