• Hypothesis of Cancer Hygiene: Helminths play a significant role
  • Soheil Sadr,1 Narges Lotfalizadeh,2 Ashkan Hajjafari,3 Fatemeh Heshmati,4 Hassan Borji,5,*
    1. Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
    2. Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
    3. Department of Pathobiology, Faculty of Veterinary Medicine, Islamic Azad University, Science and Research Branch, Tehran, Iran
    4. Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
    5. Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran


  • Introduction: Chemotherapy and surgery are traditional cancer treatment options, but they often come with severe side effects and limitations. In addition to killing cancer cells, chemotherapy can also harm healthy cells. Advanced-stage cancers may not be amenable to surgery, although it works for localized tumors. On the other hand, immunotherapy has been bringing new hope to treating cancer. The hygiene hypothesis states that children living in ultra-hygienic environments, especially those free of viruses, bacteria, parasites, and helminths, are more likely to develop cancer. Several pathogenic microorganisms have been used in cancer immunotherapy for many years. An objective of this review is to examine previous literature that has been published on tumors and helminths.
  • Methods: The search was conducted in several databases, such as Scopus, PubMed, Google Scholar, and Web of Science, for articles published between January 2000 and January 2023 that examined the antitumor effects of helminths. 700 studies have been funded as a result of keyword searches on topics such as Hygiene, Helminths, Parasites, Cancer, and Cancer immunotherapy. According to the abstracts, 500 studies were excluded, and 200 were given full-reading texts to examine. During the study, 50 articles relevant to this topic were selected with complete abstracts to be included in the analysis.
  • Results: There is mounting evidence that helminths induce immune modulation in tumor microenvironments, suppressing tumor-promoting inflammation, enhancing antitumor immune responses, and restoring normal immune balance. Based on preclinical studies, Echinococcus granulosus, Trichinella spiralis, Toxocara canis, and Taenia solium may reduce tumor growth, induce apoptosis, and modulate the tumor microenvironment. Cancer patients can benefit from helminth therapy if the treatment reduces tumor growth, stimulates the immune system, and improves survival rates. However, there is limited research to support these claims. A combination therapy, such as antigen selection and immune profiling, as well as an individualized approach based on helminth therapy, may be an avenue for improving treatment outcomes. It is possible for helminths to produce bioactive molecules directly targeting cancer cells or that their microenvironment influences the production of such molecules. There are several molecules with anticancer properties, including glycoproteins, proteins, and excretory secretions. Specific helminth-derived proteins are capable of causing apoptosis, inhibiting angiogenesis, and inhibiting metastasis in cancer cells. The antitumor properties of helminths are attributed to their stimulation of immune cells. In addition to enhancing the activity of natural killer cells (NK cells), which can recognize and destroy cancer cells directly, they may also promote the production of cytokines. Helminths may also trigger the production of cytokines that suppress excessive immune responses and attract regulatory T cells (Tregs). Helminths control chronic inflammation and inhibit tumor growth in addition to regulating the immune system.
  • Conclusion: The use of helminth-based therapy for cancer treatment is becoming increasingly popular, especially with the use of Trichinella spiralis, Echinococcus granulosus, Toxocara canis, and Taenia solium. It has been demonstrated that those helminth antigens can modulate the immune response as well as directly cause cytotoxicity in cancerous cells. In addition to offering better outcomes, helminth therapy offers fewer side effects and personalization. It would be possible to revolutionize cancer therapy through the combination of helminth properties with existing treatment modalities and provide a new avenue for healing for those suffering from cancer everywhere. Helminth therapy may improve treatment outcomes when combined with traditional cancer treatments. A more comprehensive and efficient cancer treatment plan can be developed with helminth therapy and chemotherapy, radiotherapy, or immunotherapy combined.
  • Keywords: Hygiene Helminths Parasites Cancer Cancer immunotherapy