Positron emission tomography in imaging evaluation of staging, restaging, treatment response, and prognosis in prostate cancer

Abstract

Prostate cancer is a prevalent public health problem worldwide. While imaging has played a major role in this disease, there still remain many challenges and opportunities. Positron emission tomography with various physiologically based radiotracers is fundamentally suited to interrogate this biologically and clinically heterogeneous disease along the course of its natural history. In this article, I review briefly the published evidence for the use of positron emission tomography with 18F-fluorodeoxyglucose, 11C-acetate, and 18F- or 11C-choline in the imaging evaluation of prostate cancer. Although the focus of the article will be on these radiotracers given the accumulated experience with them, but I will also comment on the outlook for the use of other emerging PET radiotracers such as those targeted to the prostate-specific membrane antigen and the amino acid metabolism pathway. It is anticipated that PET will play major role in the evaluation of prostate cancer in the current evidence-based medicine environment. There will also be exciting novel prospects for the use of therapeutic-diagnostic (theransotic) pairs in the management of patients with prostate cancer.

Keywords: Cancer; PET; Prognosis; Prostate; Response; Restaging; Staging.

Fig. 1

Incidental high FDG uptake (maximum SUV 7.7) in right prostate lobe in a 67-year-old man who presented for restaging colon cancer; further follow-up revealed a serum PSA level of 14.6 ng/mL. A subsequent biopsy confirmed prostate cancer with Gleason score of 8. (Reproduced with permission from Ref. 9).

Fig. 2

58-Year-old male with prostate cancer. A Axial T2-weighted MRI show low-signal intensity in the right mid-gland peripheral zone (white arrow), B concurrent high 11C-acetate uptake is seen in the axial PET image (black arrow), C fused 11C-acetate PET/MRI localizes the tumor (black arrow), D corresponding pathology revealed a Gleason 7 tumor. (Reproduced with permission from Ref. 19).

Fig. 3

A 63-year-old patient who had underwent radical prostatectomy and radiotherapy of primary prostate followed by androgen deprivation therapy for primary prostate cancer (pT3a, N0, Gleason score of 9, and primary PSA level of 9.0 ng/mL). At the time of imaging he presented with increasing PSA level of 22.56 ng/mL. A 18F-fluorocholine PET maximum intensity projection image shows multiple sites of pathologic increased tracer in pelvis and retroperitoneum (blue arrow). B Transaxial PET/CT images (top: 18F-fluorocholine PET; middle: CT; bottom: PET/CT) show LN metastases with high tracer uptake in right external iliac (left, yellow arrow) and common iliac (right, yellow arrow) nodal basins; CT (middle) demonstrates only small lymph nodes (red arrows). (Reproduced with permission from Ref. 66).

Fig. 4

67-Year-old male with castrate-resistant metastatic prostate cancer. FDG PET maximum intensity projection images before (A, PSA of 223.3 ng/mL) and after (B, PSA of 52.5 ng/mL) chemotherapy show marked decline in metabolic activity of multiple metastatic lesions in response to therapy.

Fig. 5

Kaplan–Meier plot of overall survival probability in men with castrate-resistant metastatic prostate cancer against sum of SUVmax of FDG-avid metastatic lesions grouped into quartiles. Patients in fourth-quartile group (blue line) have significantly poorer survival probability than reference first-quartile group (green line). (Reproduced with permission from Ref. 55).

Fig. 6

Prostate cancer-specific survival probability curves in patients with negative 11C-choline PET/CT (PET/CT−), in patients with 11C-choline PET/CT suggestive of local recurrence or lymphadenopathy (PET/CT+ LR/Lfn), and in patients with 11C-choline PET/CT suggestive of bone metastases (PET/CT+ bone). Patients with abnormal tracer uptake in the prostatic bed or in lymph nodes but no pathologic bone uptake had shorter prostate cancer-specific survival in comparison to patients with negative PET/CT but longer prostate cancer-specific survival in comparison to patients with skeletal metastatic disease. (Reproduced with permission from Ref. 59).