The effects of androgen deprivation therapy on the 18F-choline uptake in prostate cancer patients undergoing neoadjuvant treatment

BACKGROUND: To evaluate how neoadjuvant androgen deprivation therapy (ADT) can impact 18F- Choline uptake in primary prostate cancer (PC) and its metastases before radical prostatectomy (RP) or radiation therapy (RT). METHODS: We retrospectively reviewed images of 79 PC patients undergoing 18F-Choline PET/CT before RP or RT. Based on concomitant administration of neoadjuvant ADT at the time of 18F-Choline PET/CT, patients were subdivided into naïve group (Group 1) and neoadjuvant ADT group (Group 2). PET/CT results, SUVmax and metabolic tumor volume (MTV) for each site were re-assessed by two nuclear medicine physicians with more than 5 years of experience. A chi-square and a U-Mann Whitney test were used to compare the two groups. RESULTS: Sixty-two patients were included in Group 1, while 17 in Group 2. PET/CT was positive in all patients, in particular: 54 had a significant uptake in prostate alone, 12 in prostate plus lymph nodes (LN), 4 in prostate plus LN and bone, 3 in prostate plus bone and 6 in prostate plus other organs (such as lung or thyroid). PET/CT was more frequently positive in a different site, outside the prostate, in Group 1 as compared to Group 2 (p<0.001). Conversely, median SUVmax and MTV in the prostate resulted significantly lower in Group 2 than in Group 1 (5.34 vs 7.72 and 3.66 vs. 6.86 cm3, respectively; both p<0.05). CONCLUSION: PET/CT could have an important role in prostate cancer staging before primary treatment; however, before imaging, hormonal therapy status should be carefully evaluated.