Parasites as Causative Agents of Cancer

Certain parasites are known to be associated with specific types of cancer. For example:

• Schistosoma haematobium is linked to bladder cancer.
• Clonorchis sinensis and Opisthorchis viverrini are associated with cholangiocarcinoma (bile duct cancer).

These helminths are prevalent in endemic regions and are responsible for a significant number of cancer cases in those areas. Understanding how these parasites contribute to oncogenesis can help in developing strategies for prevention and treatment.

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New Insights into the Link Between Parasites and Cancer

Recent studies have shed light on the complex relationship between parasitic infections and cancer, revealing both risks and potential therapeutic implications. A systematic review published in BMC Infectious Diseases found that 28.42% of cancer patients globally are infected with intestinal parasites, with the highest prevalence among those with solid tumors (31.13%) (Wondmagegn et al., 2025). This significant finding underscores the challenges faced by immunocompromised individuals, particularly those undergoing cancer treatment.

Another study published in BMC Gastroenterology highlighted a concerning association between intestinal parasitic infections (IPIs) and colorectal cancer (CRC). The research indicated that CRC patients had a 19.67% prevalence of IPIs, with an odds ratio of 3.61, suggesting that these infections may contribute to the development and progression of CRC (Hataminejad et al., 2025).

In a groundbreaking study presented at the ESCMID Global 2025 conference, researchers explored the effects of Schistosoma haematobium, a parasite known to cause bladder cancer, on cervical cancer risk. The study revealed that women infected with S. haematobium exhibited significant changes in cancer-related gene activity, particularly after treatment with praziquantel. Notably, genes linked to tumor formation were found to be upregulated, raising concerns about the long-term implications of treatment (Mertelsmann et al., 2025).

These findings highlight the urgent need for targeted interventions and further research to understand the mechanisms by which parasites may influence cancer risk. As the global burden of cancer continues to rise, addressing the role of parasitic infections could be crucial in improving patient outcomes.

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References:

• Wondmagegn, Y. M., Setegn, A., Girmay, G., et al. (2025). Global prevalence of intestinal parasites in cancer patients: a systematic review and meta-analysis. BMC Infectious Diseases, 25, 815.
• Hataminejad, M., Basirpour, B., Baharlou, M., et al. (2025). Global prevalence and correlation of intestinal parasitic infections in patients with colorectal cancer: a systematic review and meta-analysis. BMC Gastroenterology, 25, 584.
• Mertelsmann, A. M., et al. (2025). Parasitic infection and treatment linked to cancer-related gene activity in the cervix. Presented at ESCMID Global 2025.

Potential Therapeutic Uses of Parasites

Interestingly, some research suggests that certain parasites may have anti-cancer properties. For instance, a study published in the European Journal of Medical Research discusses how various parasites, including helminths and protozoan parasites, have shown promise in combating cancers such as colorectal, lung, and breast cancers. The mechanisms proposed include:

• Immunomodulation: Parasites may help in restoring immune balance, which can be beneficial in cancer therapy.
• Inhibition of angiogenesis: Some parasites can inhibit the formation of new blood vessels that tumors need to grow.
• Molecular mimicry: This theory suggests that parasites may help the immune system recognize and attack cancer cells.

Unique Cases of Cancer from Parasites

A notable case reported by the CDC involved a patient with HIV who developed tumors from cancer cells originating in the Hymenolepis nana (dwarf tapeworm). This case raised concerns about misdiagnosis and the potential for similar occurrences in immunocompromised individuals.

Summary of Findings

Aspect	Details
Causative Agents	Schistosoma haematobium (bladder cancer), Clonorchis sinensis, Opisthorchis viverrini (cholangiocarcinoma)
Potential Benefits	Immunomodulation, inhibition of angiogenesis, molecular mimicry
Unique Cases	Tumors from Hymenolepis nana in immunocompromised patients