When Cancer Is a Parasite: A Proposed Pre-Treatment Parasitic Screening and Empirical Antiparasitic Protocol for Diagnostically Uncertain Oncological Presentations

Abstract

Background and Purpose. A patient with biliary masses, CA 19-9 of 2,000 U/mL, and suspected cholangiocarcinoma may be cured by three days of oral praziquantel. Globally, hundreds of millions of people carry parasitic infections that produce clinical, radiological, and biochemical presentations indistinguishable from malignancy — and may receive cytotoxic cancer treatment for conditions that would respond to inexpensive antiparasitic therapy. The diagnostic overlap between parasitic infections and cancer across multiple organ systems represents a clinically significant and systematically underaddressed problem. The standard clinical approach, in which cancer treatment is initiated while parasitic diagnoses are either excluded sequentially or not considered, carries two categories of risk: toxic cancer treatment delivered to patients who have parasitic infections rather than malignancy, and parasitic infections activated or worsened by immunosuppressive cancer treatment in patients who have both conditions. No formal clinical protocol addressing this specific risk has been published in mainstream peer-reviewed medical or oncology literature.

Keywords: parasitic infection; cancer misdiagnosis; antiparasitic therapy; praziquantel; albendazole; strongyloidiasis; cholangiocarcinoma; CA 19-9 biomarker response; diagnostic protocol