A diagnosis of prostate cancer (PCa) puts the brakes on one’s path in life. Wherever the patient thought he was headed, he suddenly finds himself in unknown territory. Between the upset of his inner world, and the alien territory of the medical world, it’s like finding yourself in a small boat somewhere in the middle of an ocean. As soon as possible, you want to get out of the boat by landing on the firm ground of a treatment that is right for you.

To get there, a patient needs navigational aids. Real-life sailors have long relied on maps and tools like a directional compass. For prostate cancer patients, one sort of map is guidelines that offer a big picture view and a route to safety. Your doctor then points you in the right direction toward a treatment.

Staying in the boat a while longer

However, some patients with early stage PCa decide to not get out of the boat right away. They go on Active Surveillance (AS) rather than immediately seek shore. Their low-risk PCa has been confirmed by biopsy and multiparametric MRI (mpMRI) and their doctor has determined they are candidates for AS. They want to hold off a treatment because they don’t want to risk the side effects of a whole gland treatment any sooner than they need to. They are willing to stay in the boat a while longer because

1.  They are comfortable with the idea of leaving PCa in their body,
2.  They trust that monitoring will catch any uptick in PCa in time for successful treatment,
3. And they are willing to comply with their doctor’s monitoring protocol.

How does monitoring work?

Each doctor has a preferred protocol that covers testing and scheduling. It involves PSA tests at regular intervals (e.g., every 6 months, or every year, or some combination of timing) and an mpMRI at prescribed intervals. Most protocols also include a confirmatory biopsy sooner than later. In fact, the National Comprehensive Cancer Network (NCCN) has assembled monitoring guidelines for doctors, has prepared a separate patient booklet on Early Stage Prostate Cancer in understandable words. It says, “You’ll have one biopsy to determine your diagnosis and another biopsy within a year (called a confirmatory biopsy) to see if any changes have happened over time.” They follow this guideline immediately with a caution that a biopsy may cause complications, most of which clear up quickly.

Currently, some research is calling into question the necessity of a confirmatory biopsy at one year. For example, a 2022 Australian study explored whether sequential mpMRI scans could replace protocol confirmatory biopsy at year one and even year two.^[i] For the 172 AS patients enrolled in this study, the monitoring protocol consisted of a) image-based monitoring with mpMRI scans at years 1 and 2, b) blood test monitoring of PSA density, and c) a confirmatory biopsy at the end of year 3. As long as a patient’s imaging and blood test results were stable, a biopsy was deemed unnecessary until the 3 years were completed. The authors found that the use of mpMRI and PSA density were reliable predictors of PSA progression, which immediately triggered a biopsy in any study enrollee where this occurred. As the authors report, “Biopsies during the 3-year protocol period were triggered by abnormalities on multiparametric magnetic resonance imaging and/or increases in prostate specific antigen density (>0.2 ng/ml/cc).”

Patients continued to be followed for an average of 69 months (nearly 6 years). Follow-up revealed

• 99.3% were free from biochemical recurrence (rise in PSA)
• 100% were free from metastasis
• 100% had no PCa-related death.

The authors conclude that skipping a 1-year confirmatory biopsy during AS has minimal risk to patients, provided they were thoroughly qualified initially. They state that biopsy at 3 years is advised “due to occasional magnetic resonance imaging-invisible tumors.”

On the other hand, some studies have reported that when biopsies were skipped because routine MRI was “invisible” for tumors, some patients were found through later biopsy to have more dangerous disease when their blood work or a subsequent MRI finally picked up PCa—the assumption being that it was, in fact, less dangerous when the earlier MRI failed to detect it.

In 2025, a Canadian team led by PCa expert Dr. Laurence Klotz studied “in a prospective long term cohort, the prognostic value of negative MR imaging with respect to upgrading and need for intervention in men on AS.”^[ii] They enrolled, monitored, tested, and treated (as necessary) 530 men over a period averaging 8.5 years. They found that “MRI invisible cancers demonstrated dramatically reduced rates of progression and no patient required intervention,” suggesting that invisible (negative) MRI is trustworthy.

The jury is still out. More research is needed regarding the necessity of confirmatory biopsy at 1 year on AS. mpMRI has shown high accuracy for detecting significant PCa that should be biopsied, and treated if necessary. Patients, of course, prefer not to undergo biopsy any more than necessary, and some on AS have been known to not comply with confirmatory biopsy—possibly at risk to themselves. This will remain a thorny issue for the foreseeable future, but one thing is certain: for AS monitoring, mpMRI should be performed on a 3T magnet and the scans interpreted by an expert in prostate imaging. This boosts confidence in the accuracy of an MRI scan that is invisible for tumor.

NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.

References

[i] Doan P, Scheltema MJ, Amin A, Shnier R et al. Final Analysis of the Magnetic Resonance Imaging in Active Surveillance Trial. J Urol. 2022 Nov;208(5):1028-1036.
[ii] Klotz L, Loblaw A, Zhang L, Mamedov A, Vesprini D. Prognostic value of MR visibility/invisibility in men on Active Surveillance. Prostate Cancer Prostatic Dis. 2025 Jan 17.