Navigating Uncertainty in Active Surveillance for Prostate Cancer
Radiology podcast highlights experts' experience, reflections on practice-changing research
With no clear consensus on how to measure prostate tumor change on MRI during active surveillance (AS), experts at University College London Hospital (UCLH) have published a practical MRI-based protocol designed to standardize assessment of disease progression.
Described in a “How I Do It” article published in Radiology the approach builds on the Prostate Cancer Radiologic Estimation of Change in Sequential Evaluation (PRECISE) reporting framework and provides methods for measurement of tumor volume based on the authors’ 20 years of experience.
The guidance aims to reduce the subjectivity of determining whether a lesion has changed over time on serial MRI.
“We wanted to let the community know what we’ve learned on a daily basis,” said lead author Francesco Giganti, MD, PhD, associate professor of radiology and consultant radiologist at UCLH. “There are a lot of unmet needs and limitations to PRECISE, but we can start speaking a common language.”
AS is a strategy used to avoid overtreatment in men with low- to intermediate-risk prostate cancer. Serial MRI plays an important role in monitoring disease progression and helping identify patients who may need intervention. Compared with repeat biopsy, MRI may be better tolerated by patients and more accurate for assessing radiologic change over time.
The PRECISE scoring system was developed to standardize MRI reporting in AS. Version 2 guidelines recommend measuring visible lesions at each MRI, but they do not establish an optimal measurement method.
“We have the bedrock of PRECISE, but we’re doing some logical things at UCLH which go further than the PRECISE scoring system,” said Alex Kirkham, MD, FRCR, a consultant radiologist at UCLH and senior author of the article. “We’re hoping that our current practice becomes part of future consensus.”
A Patient Centered Protocol
The UCLH protocol is centered on common-sense parameters that matter most to the patient, Dr. Kirkham noted. “The patient wants to know how big the tumor is—pea sized, grape sized, walnut sized—and he wants to know how rapidly it’s growing,” he explained. “Once you have those two pieces of information, the patient and urologist can make an informed decision.”
He said the decision to enroll in AS ultimately requires a discussion between the urologist and the patient about risk tolerance.
There are many variables, including the patient’s age, tumor type and the likelihood of progression,” Dr. Kirkham said. “It’s another reason why I think size and growth rate are important, because they convey a useful idea of the risk.”
Good candidates for AS typically have nonaggressive disease. At UCLH, that includes men with low-grade tumors not visible at MRI, as well as men with MRI-visible tumors in grade groups 1 and 2.
“For AS to be effective, radiologists need to be willing to trust MRI,” Drs. Kirkham and Giganti emphasized. “Consistency in reporting is also vital.”
The importance of concordance between histologic findings and MRI in a 54-year-old male patient enrolled in an active surveillance (AS) program locally and referred for an opinion at our institution. (A) Axial T2-weighted scan, (B) apparent diffusion coefficient (ADC) map, and (C) high–b value image at 1.5 T show a focus scoring 4/5 at the right posterolateral apex (arrow). Targeted biopsy findings were negative, but systematic sampling showed two cores of a Gleason 3+3 tumor, with a maximum core length of 5 mm, in right posterior cores. The patient was enrolled in an AS program. On review after referral, we considered the histologic features of the Gleason 3+3 tumor and these MRI scans to be discordant, with substantial restriction on the ADC map suggesting a Gleason 4 component. Repeat biopsy (with higher-quality MRI for targeting) was planned. (D–F) Repeat MRI on the day of biopsy: (D) axial T2-weighted scan, (E) ADC map, and (F) high–b value image at 1.5 T. Images are still of only moderate resolution but continue to show a focus of substantial restriction (ADC, 0.72 × 10−3 mm2/sec) in the right posterolateral peripheral zone (arrow). Targeted histologic findings obtained the same day showed a Gleason 4+3 tumor with maximum cancer core length of 8 mm. The patient elected to have active treatment by focal therapy and was not enrolled in our AS program.
https://doi.org/10.1148/radiol.242164 ©RSNA 2026
Understanding Safety and Effectiveness
In practice, PRECISE scores use a scale of 1-5 to determine whether patients can remain on active surveillance or require additional evaluation. A PRECISE score of 1 or 2 means no radiological progression, while a PRECISE 3 score means stable MRI findings over time. At UCLH, these patients can often stay in AS and avoid the anxiety and potential complications related to biopsy.
A PRECISE 4 or 5 score means radiological progression. “Changes in MRI appearance should be carefully considered with other patient factors, such as prostate-specific antigen values, ethnicity, family history and overall health,” Dr. Giganti said. “Generally, the patient can either leave AS to begin treatment or undergo repeat biopsy to inform next steps.”
AS has limitations. MRI quality, radiologist expertise and effective communication with urologists, pathologists and MRI technologists are essential. MRI can detect most high-grade tumors, but some aggressive cancers may not become visible at MRI.
The authors also note that PRECISE scores are dependent on the scan interval. After the first follow-up, if the findings remain reassuring, the interval can be progressively increased, with exact timing dependent on baseline risk and other factors. “You’re unlikely to show a difference year to year,” Dr. Kirkham noted. “On the other hand, if you scan every five years, you’re very likely to show a difference.”
To reduce variability, the authors recommend having the same reader measure lesions over time and comparing each MRI with both the baseline and most recent examinations to understand the full clinical picture.
Continuing the Conversation
Radiology’s “How I Do It” articles aim to highlight how experienced radiologists approach an important clinical problem. AS for prostate cancer is an ideal fit for the series, according to Dr. Kirkham. The format also gives experts an opportunity to self-reflect.
Drs. Giganti and Kirkham also discussed the article’s key themes on the Radiology podcast in May 2026, with cohost Refky Nicola, DO, MSc, associate professor of radiology at SUNY Upstate Medical University Center in Syracuse, NY. The Radiology podcast is one of six podcasts produced by RSNA’s peer-reviewed journals, with one podcast dedicated to each journal. Dr. Nicola is also a member of the RadioGraphics podcast team.
“The audio format is useful for exploring topics that aren’t well established and for bringing nuanced discussions to a broad audience,” Dr. Giganti said.
“I think our role as cohosts and editors is to bring to light some of the underlying issues that people may not see when they’re reading the article,” Dr. Nicola said. “We try to make the podcast understandable at every level, for the resident as well as the practicing radiologist.”
The weekly Radiology podcast has been led by associate editor Linda Chu, MD, associate professor of radiology at Johns Hopkins University in Baltimore. The team has expanded to include several cohosts from diverse subspecialties.
“The vision then and now is to disseminate the knowledge that’s published in Radiology, make the content more approachable and meet the learners where they are,” Dr. Chu said. “We want to ensure that radiologists around the world have access to cutting edge research that are important for changing clinical practice.”
Looking ahead, Drs. Nicola and Chu said future opportunities for the podcast may include translations or video podcasts to engage an even wider audience, as well as themed or cross-journal episodes.
Drs. Kirkham and Giganti agree that participating in the Radiology podcast was worthwhile “This was the best thing for us, to be able to share our experience through the podcast,” Dr. Giganti said.
He hopes that more discussion about AS for prostate cancer will encourage further research and help improve future versions of the PRECISE guidelines. “That’s why we do these things,” Dr. Giganti concluded.
For More Information
Access the Radiology article, MRI for Active Surveillance in Prostate Cancer: How I Do It
Access the related RadioGraphics review, PRECISE Version 2: Essential Tips for Prostate Cancer Monitoring Using MRI.
Explore the podcasts from RSNA’s six peer-reviewed journals.
Read previous RSNA News stories on prostate imaging: