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

Objectives To evaluate how adjuvant therapy (ADT) can impact on 18F-Choline uptake in primary prostate cancer (PC) and its metastases before radical prostatectomy (RP) or radiation therapy (RT).

Methods We retrospectively revised images of 79 PC patients undergoing 18F-Choline PET/CT before RP or RT. In according to the concomitant administration of neoadjuvant ADT at the time of 18F-Choline PET/CT, the patients were subdivided in two main groups (without and with neoadjuvant ADT, named Group 1 and Group 2). PET/CT results and SUVmax for each positive site were re-assessed by a dedicated uro-radiologist with more than 5 years of experience. A chi-square and a Kolmogorov-Smirnov test were used to compare the two groups, respectively for categorical and continuous variables. Sensibility and specificity were evaluated only in those patients treating with RP.

Results Sixty-two patients were include in Group 1, while 17 in Group 2. Seventeen patients were at intermediate and 62 at high risk of recurrent PC. PET/CT was positive in all patients, in particular: 54 had a significant uptake in prostate alone, 12 in prostate + lymph nodes (LN), 4 in prostate + LN and bone, 3 in prostate + bone and 6 in prostate + other organs (like lung or thyroid). PET/CT was more frequently positive in different site, outside the prostate, in Group1 as compared to the Group 2 (p<0.001). Conversely, median SUVmax in the prostate resulted significantly lower in Group 2 than Group 1 (5.34 vs 7.72; p=0.020). Twenty-five patients (31.6%) underwent RP, 21 in Group 1 and 4 in Group 2. In these patients, PET/CT was positive at prostate (n=18) and prostate + LN (n=7). PET/CT was true positive for prostate cancer in all patients (100% sensitivity), while 2 false positive and 2 false negative results for the LN involvement were found.

Conclusions Few studied have evaluated the impact of ADT on 18F-Choline uptake of the primary PC tumor and its metastasis before RP or RT. With the present study we evaluated how the hormonal therapy can significantly impact on SUVmax of the prostate gland and on the positive location of metastasis. PET/CT could have an important role in the prostate staging before primary treatments, however, before the imaging, a careful evaluation of the hormonal therapy status should be done.