Novel strategies against malaria and cancer create new clinical conundrums

Kenny Lin, MD, MPH
Posted on October 18, 2022

Two recent articles in American Family Physician highlight novel prevention and detection strategies against age-old health threats. In "Malaria: Prevention, Diagnosis, and Treatment," Drs. S. David Shahbodaghi and Nicholas Rathjen review not only prescribing prophylaxis for travelers to malaria-endemic regions, but also "the first malaria vaccine approved for widespread use ... for the prevention of P. falciparum malaria in children living in endemic areas," which has already been given "to more than 1 million children in Ghana, Malawi, and Kenya." In a previous AFP Community Blog post, Dr. Jennifer Middleton discussed the World Health Organization's endorsement of Mosquirix and research evidence that it lowers the incidence of malaria infection, complications and death in combination with seasonal chemoprophylaxis.

A New York Times article elaborated on the financial, logistical, and trust challenges of getting an estimated 100 million vaccine doses into children's arms every year. A full series of Mosquirix consists of 4 doses administered between 5 and 18 months of age. Its limited (40%) efficacy compared to other malaria vaccines in development has raised concerns that "every dollar directed to Mosquirix now is a dollar less for developing other tools" and paying for low-tech prevention measures such as distribution of insecticide-treated bed nets.

Despite a 27% decline in cancer mortality in the U.S. over the past two decades, cancer trails only heart disease as the leading cause of death, and most cancer types do not have screening tests recommended by the U.S. Preventive Services Task Force (USPSTF). The October issue's Diagnostic Tests feature by Dr. Natasha Pyzocha discusses the Galleri test, a blood test that is used to detect more than 50 cancer types in older adults. The test's manufacturer recently reported results of a prospective study of the test that detected a "cancer signal" in 1.4% of participants, 38% of whom ultimately had cancer confirmed after additional diagnostic testing. A much larger study currently underway in the United Kingdom's National Health Service should go a long way toward determining if this test is a "game changer" or "overhyped" for improving cancer outcomes and mortality.

Several other multi-cancer early detection (MCED) tests are in various stages of development, and the future impact of MCEDs on family physicians who may be ordering these tests in practice is uncertain. A review in the American Journal of Medicine mentioned "concerns about patient counseling, costs, frequency of testing, patient anxiety, and subsequent testing for a positive result." Similarly, the director of the National Cancer Institute's Division of Cancer Prevention wrote that "there is still a substantial level of uncertainty and many unknowns surrounding these tests," including "how best to maximize their benefits and minimize their potential harms." To provide primary care clinicians with more context, AFP has an editorial in production that will discuss basic test evaluation principles and data requirements needed to justify routinely using these tests for cancer screening in practice, particularly for cancers that already have USPSTF-recommended screening tests.