• Posted August 1, 2025

Are Some 'Low-Grade' Prostate Cancers More Deadly Than Thought?

Men diagnosed with what are known as Grade Group one (GG1) prostate tumors are often told they don’t require treatment, only “watchful waiting,” because GG1 cancers are at low risk of spreading.

There’s even been talk among experts of not calling GG1 tumors “cancers” at all.

However, new research suggests that in up to 30% of these cases the risks may be higher than thought, and a more nuanced view of GG1 tumors could help save men’s lives. 

“We don’t want to miss aggressive cancers that initially present as Grade Group one on biopsy,” explained study co-senior author Dr. Bashir Al Hussein, an assistant professor of urology and population health sciences at Weill Cornell Medicine in New York City. “Such underestimation of risk could lead to undertreatment and poor outcomes.”

The new study outlining these uncertainties was published July 31 in JAMA Oncology.

Prostate cancer is often slow-growing and highly treatable, according to the American Cancer Society. However, it remains very common, with 313,780 new cases of prostate cancer expected this year and 35,770 related deaths.

A man’s prostate biopsy can have varying results, from noncancerous to cancers that present a high level of risk and must be treated.

Currently, a GG1 biopsy result often means the patient is told to forgo treatment for now, but have the tumor periodically assessed to see if they are showing signs of progression.  

This “active surveillance” might include blood tests to monitor levels of PSA (a cancer-linked protein produced by the prostate), follow-up biopsies and/or MRI scans, Al Hussein and his colleagues said.

However, the research team stressed that one biopsy cannot sample the prostate as a whole, and aggressive cancer cells might still be missed. 

In the new study, Al Hussein’s team took a close look at data on more than 300,000 men diagnosed with cancers that had not spread beyond the prostate. 

About 117,000 of these patients were classified as having a GG1 tumor after initial biopsy.

However, the researchers also used other factors — for example, circulating levels of PSA and tumor size — to better assess an individual’s risk for the tumor to spread.

Based on the combined data, they estimate that more than 18,000 of the men had higher risk cancers that should be treated with radiation therapy or removal of the prostate. 

In other words, “our data show that up to 30 percent of patients who were diagnosed with GG1 but were in the higher risk category underwent active surveillance [only], which means they were potentially undertreated,” Al Hussein said in a Weill Cornell news release.

The new findings come at a time when some clinicians are debating dropping the cancer label for GG1 tumors altogether.

Study co-senior author Dr. Jonathan Shoag, associate professor of urology at Case Western Reserve University in Cleveland, is convinced it's time to put the brakes on that notion.

“There is a misunderstanding that ‘low grade’ and ‘low risk’ are the same. Here, we show clearly that they are not,” Shoag said in the Weill Cornell release. “Attempts to rename GG1 are misguided as many patients with GG1 cancers on biopsy have substantial risks of their cancers causing pain and suffering over their lifetime if untreated.”

The notion, according to Shoag, that all GG1 tumors are low-risk stems from evidence that was largely based on tissue samples from removed prostates. 

For an individual patient, that’s not the same as relying on the results of a single biopsy, however. 

“As clinicians, we must make decisions based on each patient and his biopsy results in that context,” Shoag said. 

Al Hussein agreed.

“We need to find a better way to inform patients about their prognosis when they have GG1 prostate cancer with adverse clinical features,” he said. 

“As physicians, the responsibility falls on us to educate patients and provide them with the information they need to understand their diagnosis and decide on the best approach for treatment, while continuing to advocate for active surveillance for those who are indeed low risk,” Al Hussein added.

More information

Find out more about prostate cancer diagnosis at the American Cancer Society.

SOURCE: Weill Cornell Medicine, news release, July 31, 2025