IBD increases prostate cancer risk by fivefold

Inflammatory bowel disease (IBD) is characterized by a range of gastrointestinal symptoms, including diarrhea, bloating, and cramps.

Two of the most common forms of IBD are Crohn’s disease and ulcerative colitis.

These conditions affect an estimated 3 million people in the United States, according to the Centers for Disease Control and Prevention (CDC).

People with IBD have an increased risk of cancers of the gastrointestinal tract. However, the links between IBD and prostate cancer are not well-known.

Recently, researchers at Northwestern Medicine in Chicago, IL, set out to investigate whether or not a relationship exists.

IBD and prostate cancer

Though controversial, doctors often use the prostate-specific antigen (PSA) blood test to screen for prostate cancer. Normally, levels of PSA in the blood are low. If there is a significant increase, it can sometimes be a sign of prostate cancer.

However, men with IBD often have higher levels of PSA, possibly due to the chronic inflammation associated with the gastrointestinal condition.

Some researchers believe that certain inflammatory products, such as C-reactive protein, might boost levels of PSA without the presence of prostate cancer.

Because PSA levels can be high in people with IBD, they are often ignored. Understanding prostate cancer risk in this population is therefore important to help guide clinical decisions.

To investigate, the scientists followed 1,033 men with IBD and 9,306 men without IBD as a control group. On average, they followed each participant for 18 years. The average age at the beginning of the trial was 53.

They recently published their findings in the journal European Urology.

The scientists found that the prostate cancer risk for men with IBD was roughly five times greater than it was for those without the condition. The authors conclude:

[O]ur study is the first to demonstrate an increased risk of clinically significant [prostate cancer] for men with IBD.”

Explaining the link

In their paper, the authors also discussed why this relationship might exist. How could IBD increase the risk of prostate cancer?

They theorize that, rather than being due to excessive inflammation, it might be due to a reduction in immune surveillance.

Immune surveillance is our immune system’s ability to pick off lone circulating cancer cells. The theory is that immune cells — which identify and destroy cancer cells before they take root and begin to cause harm — continuously patrol our bodies.

Doctors often prescribe people with IBD medications that reduce the body’s immune response. It could be that these drugs also reduce the vigilance of the immune surveillance system.

The authors also note that both prostate cancer and IBD have a significant genetic component. It may be that some of the genes involved are shared across both conditions.

In the clinic

These new findings may change how doctors help people with IBD manage their condition. Lead author Dr. Shilajit Kundu explains:

“These [people] may need to be screened more carefully than [those] without inflammatory bowel disease. If a man with inflammatory bowel disease has an elevated PSA, it may be an indicator of prostate cancer.”

This finding is sure to open a debate surrounding PSA and prostate cancer in men with IBD. New guidelines may be necessary.

Dr. Kundu explains how he often sees elevated PSA in people with IBD in his clinic, saying, “Many doctors think their PSA is elevated just because they have an inflammatory condition. There is no data to guide how we should treat these men.”

Further work will be needed to gather a better understanding of the relationship between these conditions; and because of the high prevalence of IBD, this research will surely follow quickly.

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