ACS Research Highlights

"Forever Chemicals" Not Linked with Prostate Cancer in Older Men

PFAS in many consumer products show no strong link with an increased risk for prostate cancer, but these "forever chemicals" need more research.

The Challenge

PFAS (per-and polyfluoroalkyl substances) are lab-made chemicals found in many consumer products, ranging from water- and stain-resistant fabrics to non-stick coatings on cookware. They're also used in industrial products like the foam firefighters use to put out errant flames. There are thousands of PFAS types. They’re widely used because they are stable, meaning they don’t interact much with other chemicals.

The downside of PFAS’ stability is they don’t break down easily and can stay in the human body and the environment for a long time, making them a health concern and potential carcinogen. That's why PFAS are also known as "forever chemicals."

The two most used PFAS in the United States—PFOA and PFOS—are no longer made in this country, but people can still be exposed to them from imported products or other PFAS that are still produced in the US. 

Levels of these chemicals can be especially high in workers that use PFAS, such as chemical plant employees and firefighters.

Previous studies of potential health effects of exposure to PFAS focused on highly exposed men who worked in PFOA-related chemical plants and communities with high exposures to PFAS-contaminated drinking water. These studies identified links between various PFAS and cancers of the testis and kidney.

Findings from those studies were mixed about whether highly exposed men had a possible increased risk for developing prostate cancer.

Few studies have evaluated the effect of lower levels of PFAS exposure, like those experienced by the general population.

The Research

American Cancer Society (ACS) researchers Lauren Teras, PhD, Ryan Diver, MSPH, James Hodge, JD, MPH, and Ying Wang, PhD, worked with researchers at the Centers for Disease Control and Prevention (CDC) to further understand the relationship between PFAS exposure and several types of cancer in the general population. They published a recent study that focused on prostate cancer in Environmental Research.

The researchers examined PFAS levels in a group of men in the ACS Cancer Prevention Study II (CPS-II) Lifelink Cohort Study who provided blood samples. Though some of the men were later diagnosed with cancer, at the time they donated their blood, they had never been diagnosed with cancer. This is important because studies that measure PFAS and other chemicals after a cancer diagnosis are not able to determine whether the PFAS level was affected by the cancer or its treatments, rather than the other way around.

During the follow-up period, the researchers identified 1,610 men from the cohort who were diagnosed with prostate cancer, along with a comparison group of men who did not get prostate cancer. The study is believed to be the largest of its kind, and its size enabled researchers to study PFAS exposures at levels seen in the general population.

The findings from this study suggest that PFAS may increase prostate cancer risk for some groups of men but do not play a major role in prostate cancer risk overall.”

Lauren Teras, PhD

Senior Scientific Director, Epidemiology Research

American Cancer Society

Researchers measured participants’ blood samples for four types of PFAS. Then they evaluated the association between PFAS, prostate cancer, and selected lifestyle, medical, and demographic characteristics of the study participants.

The study did not show a consistent link between PFAS and a higher risk for developing prostate cancer. 

However, they did find links between exposure to PFAS and a higher risk of developing prostate cancer in these specific sub-populations:

  • Men without a family history of prostate cancer
  • Men who did not consume alcohol
  • Men with a higher education
  • Men aged 70 to 74
No associations were observed between the PFAS and tumor grade or stage. 
 
The larger study about the effect of PFAS on several cancers was published in Environmental Health Perspectives (EHP), the journal for the National Institute of Environmental Health Sciences. This study examined the effect of PFAS and cancers in the breast, bladder, kidney, pancreas, prostate, and hematological system (blood, bone marrow, and lymph nodes).
 

Like previous studies, researchers found a link between the most common type of kidney cancer (renal cell carcinoma) in women and PFOA. Among men, they also found a new connection between PFHxS and chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL).

Results of the EHP study were considered in the IARC’s (International Agency for Research on Cancer) evaluation of PFOA and PFOS, the two most commonly studied PFAS. They found PFOA to be a human carcinogen (Class 1) and PFOS to be possibly carcinogenic (Class 2B).

Why It Matters

Over the last decade, interest in PFAS has grown due to the unknown health effects of these chemicals that stay in both the environment and the body for long periods of time. 

This large study provides more insights into how PFAS may be linked to prostate cancer in the general population. This is important because of the common and long-lasting exposure to PFAs.

To determine whether PFAS cause cancer, ACS researchers point to the need for more well-designed, large studies to further investigate subgroups to understand the complicated relationships between PFAS and medical, demographic, and lifestyle risk factors for prostate cancer.