HPV and Prostate Cancer – Scientists Pursuing an Unknown Link

Prostate cancer is the second most common cancer in men worldwide after lung cancer. Approximately 20 thousand cases are diagnosed annually in Turkey, accounting for 15% of all cancers in men.

Although many risk factors contribute to prostate cancer development, the factors that initiate it have not yet been identified. This has encouraged research into new causal factors associated with this cancer.

Human papillomaviruses (HPV), particularly high-risk types, have been identified as carcinogenic (cancer-causing) agents in humans. HPVs are small, nonenveloped viruses that can infect the skin and genital region, causing hyperproliferative lesions known as warts or papillomas. More than 200 HPV types have been discovered and classified as “low risk” or “high risk” according to their association with cancer development. Low-risk types cause benign lesions, while high-risk types have carcinogenic properties.

Long-term viral persistence requires evasion of the body’s immune attacks and clearance for cancer to develop. HPV has been shown to interact with three main oncoproteins, E5, E6 and E7, to suppress the human immune system. Infections are generally cleared by the immune system after a period of latency, but under suitable environmental conditions the virus can evade immunity and cause cancerous change.

High-risk HPV types are considered the most important causal factor in 95% of cervical cancer cases. HPV has also been found to cause many other cancers. These findings may suggest that HPV can move from its original infection site to other organs and be responsible for cancer development in various organs.

The relationship between HPV and prostate cancer is considered important for several reasons. 

In 1951, Ravich proposed that sexually transmitted diseases (STDs) could contribute to prostate cancer development. Many studies have since focused on the association between STDs and prostate cancer. STDs generally increase prostate cancer risk by causing prostate inflammation followed by cancer development. In 2019, Vignera and colleagues reported persistent high-risk HPV DNA in the semen of 82% of patients with prostatitis.

Until recently, study results were highly controversial, and concrete evidence of HPV’s presence in prostate cancer was still lacking. Given the wide interest in the relationship between high-risk HPV and prostate cancer, confirming the frequency of HPV types other than 16 and 18 in prostate tissue worldwide is considered very important.

Given prostate cancer’s global prevalence and the possibility that high-risk HPV triggers its development, it is surprising that no research had examined HPV infection’s effect on prostate cancer in the United Kingdom. Aiming to fill this gap, a team led by internationally recognized HPV-cancer researcher Hossein Ashrafi conducted an important study. Ashrafi’s doctoral student Yahya Ahmed is the lead author, and the team also includes Turkish scientist Muharrem Okan Çakır. Using sensitive molecular analyses, the team examined 12 high-risk HPV types in benign and cancerous prostate tissue collected in the United Kingdom. This is an important step toward understanding HPV’s potential effect on prostate cancer.

Study Details

In this study, the authors used a sensitive molecular analysis to detect HPV DNA in prostate tissue samples from 49 men in England.

In brief, the study found:

• HPV DNA was present in 32.7% of all prostate tissue samples and 35.7% of prostate cancer tissue samples.
• The most common HPV types in prostate tissue were HPV 16, 31, 33 and 35.
• Prostate cancer tissue samples contained more HPV DNA than prostate tissue from men with benign prostatic hyperplasia (BPH).

The authors concluded that their findings suggest HPV may play a role in prostate cancer development and could have implications for developing new treatments. They also stated that further research is needed to confirm the findings and establish HPV’s precise role.

Until now, prostate cancer had no clear link to preventable risk factors such as high-risk HPV infection. However, this study shows that high-risk HPV is present in prostate tissue.

The study suggests that biologically active HPV infection lasting for years plays a role in prostate cancer development. The findings matter because they suggest HPV could be a preventable prostate cancer risk factor. If confirmed, this could lead to new prevention and treatment strategies.