Not All Prostate Cancer Follows a Slow-Growing Course

About one in six men with grade group 1 prostate cancer have higher-risk disease, showing outcomes vary and biopsy grade may underestimate risk.

Roughly one in six men with grade group 1 (GG1) prostate cancer have intermediate- or high-risk disease, and GG1 can have heterogeneous long-term outcomes, suggesting that not all GG1 prostate cancer follows a slow-growing course, and relying on biopsy grade alone can lead to an underestimation of disease risk, according to study findings published in JAMA Oncology.

“There's good rationale to remove this cancer label: the majority of men with prostate cancer are low risk at diagnosis, and the preferred treatment for these patients is active surveillance. However, population-based data show that rates of active surveillance for low-risk, low-grade disease are still not 100%,” Dr. Neal Patel, lead study author, said in an interview with CURE. Patel is a urologic oncologist and an assistant professor of urology at Weill Cornell Medicine.

He continued, “By removing the cancer label, the goal would be to increase the number of patients with low-grade, low-risk disease who are not treated. Based on our study, though, there is a subset of men diagnosed with grade group one prostate cancer on biopsy who have adverse clinical features that may increase their risk of developing metastasis. Even though this is a smaller subset of all men with grade group one prostate cancer, we believe this group needs further study before considering steps such as dropping the cancer label.”

In a cohort of 117,162 men with biopsy GG1 prostate cancer, 10,440 had favorable intermediate-risk disease, 3,145 had unfavorable intermediate-risk disease and 4,539 had high-risk disease. The median age was 64 years. High-risk GG1 disease was associated with adverse pathology at prostatectomy in 867 men. Prostate cancer–specific mortality was 2.4% for unfavorable intermediate-risk GG1 and 4.7% for high-risk GG1, similar to 2.1% for favorable intermediate-risk GG2 and 4% for unfavorable intermediate-risk GG2 or higher. After adjusting for other factors, favorable intermediate-risk, unfavorable intermediate-risk and high-risk GG1 disease were all linked to higher prostate cancer–specific mortality compared with low-risk GG1.

“The purpose of this article is to highlight that there is a group of patients who are not low risk and have not been well represented in active surveillance studies,” Patel said. “Before taking the drastic step of removing the cancer label, we need to better understand this subset of patients.”

A grade group is a way of describing prostate cancer based on how abnormal the cancer cells look under a microscope and how quickly they are likely to grow and spread. Scores range from 1 to 5, with lower scores indicating cells that resemble normal tissue and tend to grow slowly. The system helps guide treatment decisions and predict outcomes.

Trial Design

Researchers conducted a population-based study using United States cancer registry data to examine outcomes in 117,162 men diagnosed with localized grade group 1 prostate cancer between 2010 and 2020. Men were grouped by National Comprehensive Cancer Network risk categories. The study analyzed cancer-specific mortality and links between biopsy results and adverse findings at prostate removal surgery. Data were reviewed from July to October 2024.

“One of the limitations of our study was that we couldn't account for the use of prostate MRI,” said Patel. “Many people think that with a prostate MRI and a targeted biopsy, the diagnosis of grade group one decreases, and higher-grade cancers are not missed. However, MRI is not perfect and has its own limitations. Ensuring that patients receive state-of-the-art imaging and are seen at a multidisciplinary center with urologists who specialize in prostate cancer is very important.”

Reference

“Grade Group 1 Prostate Cancer Outcomes by Biopsy Grade and Risk Group,” by Dr. Neal A. Patel, et al., JAMA Oncology.

For more news on cancer updates, research and education, don’t forget to subscribe to CURE®’s newsletters here.