Ga-68 PSMA PET/CT Promising New Technique for Predicting Risk Stratification and Metastatic Risk of Prostate Cancer Patients - Chen Liu
December 11, 2019
Chen Liu, PhD, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute Beijing China
Chen Liu: Good afternoon, everyone. I'm Dr. Liu from Peking University Cancer Hospital. I'm very pleased to share our research in this topic, "Gallium-68 PSMA 617 PET/CT, A Promising New Technique for Predicting Risk Stratification and Metastatic Risk of Prostate Cancer".
Prostate cancer is the second most common cancer in males, and it is the fifth leading cause of cancer deaths in men worldwide. To improve the clinical outcome of patients, accurate rates of stratification of prostate cancer in patients before treatment is vital. For low risk and intermediate-risk prostate cancer patients, good prognosis and longer biochemical recurrence-free survival may be achieved by active surveillance and radical prostatectomy and radiotherapy. High risk of prostate cancer patients are at higher risk of increase of metastasis, recurrence and high mortality.
Although there are many risks of stratification [inaudible 00:01:41] being introduced, the definition of high-risk prostate cancer has not been standardized. So, there is a need for an objective and accurate imaging biomarker for the diagnosis of prostate cancer.
In our study, we explore the possibility to establish a noninvasive prostate cancer risk stratification criteria based on imaging analysis. We aim to investigate the performance of gallium-68-PSMA PET/CT in predicting the risk of stratification and metastasis risk of prostate cancer.
Forty newly diagnosed patients with biopsy-confirmed prostate cancer were included in our study, and gallium-68-PSMA PET/CT, and clinical data of old patients were retrospectively analyzed. According to the risk of stratification set of theory of the NCCN guidelines, patients were simply divided into low to intermediate-risk groups and high-risk groups. The semi-quantitatively parameters of gallium-68-PSMA PET/CT were used to establish a logistic regression model for high-risk of prostate cancer and its metastatic risk. We also evaluated the diagnostic efficiency of the predictive model.
The PET/CT image was analyzed visually and the semi-quantitative by measuring the SUVmax, IPSAMA-TV and ITL-PSMA. The median age of 40 patients was 67 years old, and their median PSA level was 35. The Gleason score from trans-guided biopsy were six in four patients, seven in 16 patients, eight in eight patients, nine in 10 patients, and 10 in two patients.
Visual analysis in gallium-68-PSMA PET/CT was able to detect 95% of primary prostate cancer. In addition, the results show that there are increasing trends of gallium-68-PSMA uptake in the prostate tumor lesions with the Gleason score. According to the NCCN guidelines, there were 10 patients in the low to intermediate-risk group and 30 patients in high-risk group. The SUVmax, IPSMA-TV, and ITL-PSMA, can be a semi-quantitatively imaging biomarker to predict the risk of stratification of prostate cancer. And the area under the ROC curve was 0.843 for the SUVmax model, and 0.8024 for the IPSMA-TV, and 0.9 for the ITL-PSMA model.
Okay. Let's go back to the best definition of high-risk of prostate cancer. What is the best definition of high-risk prostate cancer? Mark an answer in this article. It says that "the optimal definition of high-risk cancer should ultimately be a balance that favors high sensitivity, whereby all patients with locally advanced and occult metastatic disease are included, with an acceptable level of specificity, whereby most patients with otherwise organ-confined disease are excluded".
And gallium-68-PSMA PET/CT as a whole-body and non-invasive imaging examination could both evaluate the primary prostate cancer and metastatic lesions. In a series of studies, gallium-68-PSMA PET/CT, not only a [inaudible 00:06:13] traditional examination in terms of the diagnosis efficiency, but also can reflect malignancy of prostate cancer.
So, the gallium-68-PSMA PET/CT has its own advantage in predicting the high-risk of prostate cancer. So in our study, we preliminarily confirmed that gallium-68-PSMA PET/CT imaging can be used as imaging biomarkers to predict the risk stratification and the metastatic risk of prostate cancer. Finally, I want to express my gratitude to my own members in my department in contributing to this study. Thank you for listening.
Speaker 1: Thank you very much. The paper is open for comments or questions.
Speaker 3: Hi, nice work. So, two questions. One is, how did you obtain the tumor volumes in the total lesion? So, there were parameters. What method did you use?
Chen Liu: We used automatically under threshold ROI.
Speaker 3: Okay. So, a fixed threshold.
Speaker 1: The fixed threshold for SUV, what did you use? What number for SUV for fixed threshold? To say something is tumor or not tumor in the region of interest?
Speaker 3: So you picked up an SUV threshold, and then all the [inaudible 00:08:00] with an uptake above this threshold was assessed as tumors?
Chen Liu: Above-
Speaker 3: The threshold.
Chen Liu: ... 40% of the max.
Speaker 3: Sorry.
Speaker 1: 40% of the max.
Speaker 3: Okay, 40%. Okay. And second, did you try to implement the PSA values in the multi-regression analysis? I think you would adjust the SUVmax and the parameters, right?
Chen Liu: Yeah.
Speaker 3: So, did you already try to use the PSA values?
Speaker 1: Oh, you're just wondering if you also use PSA as one of the parameters in your statistical calculation?
Chen Liu: No.
Speaker 1: No, they didn't.
Speaker 3: Thank you.
Speaker 1: Okay. Are you using gallium-68 routinely at Beijing hospital now, or this is just research? Do you use it every day for the clinic?
Chen Liu: Just a little research-
Speaker 1: Just research, okay. All right. Thank you so much.