How To Implement Next-Generation Imaging Recommendations in Prostate Cancer Management

Next-generation imaging may allow for the detection of metastatic prostate cancer that is otherwise not detected with conventional imaging. Therefore, guidelines for its use will be key moving forward.

At the New York GU 14th Annual Interdisciplinary Prostate Cancer Congress® and Other Genitourinary Malignancies, Phillip J. Koo, MD, discussed the recommendations issued for the early detection of metastatic prostate cancer using next-generation imaging.¹

“The purpose of this was to help provide guidance with regards to the use of conventional imaging to identify metastatic disease in patients with prostate cancer. And we created 3 buckets” of patients with newly diagnosed disease, biochemically recurrent tumors, and M0 castrate-resistant prostate cancer (CRPC), explained Koo, who is chief of diagnostic imaging at Northwest Region Oncology and physician executive at Banner MD Anderson Cancer Center in Phoenix, Arizona, during a presentation at the meeting.

“One of the reasons why we did this was because we knew that metastatic disease was being underdiagnosed in a lot of our patient populations because we weren’t imaging frequently enough,” Koo said.

Newly Diagnosed Prostate Cancer

For newly diagnosed prostate cancer in the RADAR I recommendations for early detection of metastatic disease, Crawford and colleagues recommended to scan high- and intermediate-risk tumors with at least 2 of the following criteria: prostate-specific antigen (PSA) level greater than 10 ng/mL, Gleason score of 7 or greater, or palpable disease (≥T2b).²

In his presentation, Koo referenced an abstract presented at the 2020 American Society of Clinical Oncology Virtual Scientific Program about a prospective trial–which was designed to evaluate 68Ga-PSMA-11–that showed a sensitivity of 40% and specificity of 95% to detect pelvic nodal metastases. Moreover, the results demonstrated that patients with larger nodes, higher preoperative PSA, and higher Gleason score experienced an increase in sensitivity to the next-generation imaging; and 87% of patients with positive disease experienced biochemical recurrence after surgery.³ Of note, Koo said, optimal management based on PSMA-PET results have yet to be confirmed.

In the updated recommendations, which incorporated next-generation imaging PET, Koo and colleagues suggested that if conventional imaging is equivocal or negative with continued high suspicion for metastatic disease, next-generation imaging should be considered.⁴

“I think the optimal management of these patients who actually have [prostate secretory protein]–positive disease is really yet to be known,” Koo said. “So that’s why I think our recommendation that we first gave 3 years ago still holds true. If your conventional imaging is equivocal or negative, but you still have a high suspicion for metastatic disease, you should consider [next-generation imaging]. It doesn’t mean you absolutely need to get it, but you should think about getting it and think about how it’s going to impact your treatment decisions.”

For example, he added, if the PSMA-PET CT is negative, then the patient would move on to prostatectomy or radiation. However, if the image results are positive, the next questions health care providers should ask are: Is it local or regional metastases? Is it distant metastatic disease? Is it low volume versus high volume?

“That’s probably going to impact how you manage these patients,” Koo said.

Biochemical Recurrence in Prostate Cancer

For biochemical recurrence in prostate cancer, the RADAR I recommendations comprised the following:

• First scan when PSA levels are between 5 and 10 ng/mL
• Imaging frequency, if negative for previous scan: Second scan when PSA equals 20 ng/mL, and every doubling of PSA level thereafter, based on PSA testing every 3 months.2

“We know that 30% of patients aren’t cured with initial treatment, and we know that you are going to be dealing with this disease state in your practices. Biochemical recurrence is challenging, and I think there’s been a lot of limitations,” Koo said.

In the updated recommendations, Koo and colleagues recommended for health care providers to consider next-generation imaging for a PSA of 0.5 ng/mL or greater, and a PSA below 0.5 ng/mL can be considered based on specific performance of various next-generation imaging techniques.³

“If [next-generation imaging results are] positive, I think it raises a lot of questions. Is it locally recurrent? That’s fine. That’ll help impact how you manage that patient,” he said. “Does it have regional metastases? Or do you have distant metastases on the PSMA? And is it all a metastatic disease or is it polymetastatic disease? I think all that is going to impact how you manage that patient.”

Castrate Resistant Prostate Cancer

For M0 CRPC, the RADAR I recommendations were for the first scan to occur when PSA levels were greater than 2 ng/mL. And then, imaging frequency, if negative for the previous scan, would consist of a second scan when PSA was equal to 5 ng/mL and every doubling of PSA thereafter, based on PSA testing every 3 months.²

However, with the RADAR III recommendations, Koo and colleagues suggested that a health care provider only consider next-generation imaging when PSA doubling time was less than 6 months, when M1 therapies would be appropriate.⁴

Moreover, with M1 metastatic CRPC, the recommendation suggests utilizing conventional scans and consider next-generation imaging only if conventional scans are negative and the clinician still suspects disease progression. In this instance, next-generation imaging would be based on at least one of the following: with every doubling of PSA since the previous image; every 6 to 9 months in the absence of PSA rise; change in symptoms; and change in performance status.

Implementing into Practice

As this technology continues to advance, Koo noted that next-generation imaging will lead to a change in the management of patients with prostate cancer.

“There is growing data regarding improvement in outcomes,” he added. “And that’s something that we’re going to have to stay tuned on. But in the end, [next-generation imaging] is here to stay. It’s not going anywhere.”

Therefore, Koo offered take-home points for health care providers. “Have a strategy before using [next-generation imaging]. [It will] help you be prepared and maximize the value of that test. And the other way to maximize the value is to build your own multidisciplinary team,” he said. “…So in the end, stay tuned, because this is rapidly changing, but it’s very exciting.”

Reference:

1. Koo PJ. Next Generation Imaging in Prostate Cancer. Presented at: 14th Annual New York GU Congress; March 12-13, 2021.

2. Crawford ED, Stone NN, Yu EY, et al. Challenges and Recommendations for Early Identification of Metastatic Disease in Prostate Cancer. J Urol. 2014;83(3):664-669. doi: 10.1016/j.urology.2013.10.026

3. Hope TA, Armstrong WR, Murthy V, et al. Accuracy of 68Ga-PSMA-11 for pelvic nodal metastasis detection prior to radical prostatectomy and pelvic lymph node dissection: A multicenter prospective phase III imaging study. J Clin Oncol. 2020;38(suppl 15):5502. doi:10.1200/JCO.2020.38.15_suppl.5502

4. Crawford ED, Koo PJ, Shore N, et al. A Clinician's Guide to Next Generation Imaging in Patients With Advanced Prostate Cancer (RADAR III). J Urol. 2019;201(4):682-692. doi:10.1016/j.juro.2018.05.164.