Hepatitis B exposure declines among cancer patients, yet disparities persist

Hepatitis B virus remains one of the most consequential viral pathogens in oncology, and a new fourteen-year analysis from Brazil shows that while exposure to the virus is steadily falling among people with cancer, it is far from disappearing. Researchers at the University of São Paulo examined nearly 29,000 adult cancer patients treated at a major quaternary oncology center between 2010 and 2023 and found that the proportion carrying antibodies indicating past or present HBV infection dropped from 16.5 percent to 9.9 percent over the study period. The decline, reported in the journal Cancer Causes & Control, is encouraging evidence that vaccination and changing screening practices are reshaping the viral landscape faced by oncologists. Yet the same data reveal stubborn gaps: men, older adults, and non-White patients continue to bear a disproportionate burden of previous HBV exposure, and a substantial share of admitted cancer patients were never tested at all.

The clinical stakes of this epidemiology are considerable. Hepatitis B virus infects hepatocytes and can establish a chronic infection that progresses to cirrhosis and hepatocellular carcinoma; infection is recognized as one of the strongest risk factors for liver cancer, raising the odds of that malignancy by roughly 47-fold. Globally, an estimated 240 million people live with chronic HBV infection. For cancer patients, the virus carries an additional threat: systemic anticancer therapies suppress immune function, which can permit viral replication to resume even in patients whose infection appeared resolved. This reactivation is driven by covalently closed circular DNA, a persistent viral reservoir that remains within the nucleus of hepatocytes long after serological recovery. A recent global meta-analysis estimated reactivation rates of approximately 10 percent among patients with hematological malignancies and 5 percent among those with solid tumors.

Reactivation is not a benign event. It can force interruption, delay, or modification of cancer treatment precisely when therapy is most needed, and it may culminate in acute hepatitis, liver failure, and death. For this reason, international guidelines recommend screening for HBV before patients begin chemotherapy or other immunosuppressive regimens. Patients who test positive for the hepatitis B surface antigen should receive antiviral therapy with agents such as entecavir, tenofovir disoproxil fumarate, or tenofovir alafenamide, while those who are surface-antigen negative but positive for antibody against the core antigen, known as anti-HBc, should be considered at risk of reactivation and managed with antiviral prophylaxis or serological and molecular monitoring. Despite these recommendations, screening remains inconsistently implemented across oncology centers worldwide.

The São Paulo study drew on laboratory records from the São Paulo State Cancer Institute, affiliated with the Clinical Hospital of the university’s Faculty of Medicine, which has treated more than 140,000 cancer patients since opening in 2008. Of 125,985 patients admitted between 2010 and 2023, 28,869, or 22.9 percent, underwent anti-HBc testing. The mean age of those tested was 56 years, roughly two-thirds were women, and 61.4 percent self-identified as White. Solid tumors accounted for 71.2 percent of the cohort, with breast cancer the most common diagnosis, while hematological malignancies made up 22.2 percent, led by non-Hodgkin lymphoma and multiple myeloma. HBV exposure was defined as anti-HBc positivity, a marker that indicates prior contact with the virus but does not by itself distinguish resolved infection from active disease.

The headline finding is a statistically significant downward trend in seroprevalence, from 16.5 percent in 2010 to 9.9 percent in 2023. The decline was broad but uneven. Among men, seroprevalence fell from 25.1 percent to 12.3 percent, a steeper drop than among women, whose rates fell from 11.4 percent to 8.3 percent. Every age group improved, including patients aged 18 to 39, whose seroprevalence fell from 7.7 percent to 2.4 percent, and those aged 60 and older, whose rates declined from 20.1 percent to 13.7 percent. Seroprevalence also fell significantly among White patients and among those with solid tumors. By contrast, no significant trend emerged among non-White individuals, whose rates moved only from 21.4 percent to 17.7 percent, or among patients with hematological malignancies, whose rates remained essentially flat at around 13 percent.

Multivariable logistic regression sharpened the demographic picture. Patients aged 60 or older had 4.4-fold higher odds of HBV exposure than those under 40, men had 89 percent higher odds than women, and non-White patients had 25 percent higher odds than White patients. The age gradient likely reflects cumulative lifetime exposure in cohorts born before universal neonatal vaccination, compounded by the reduced immunogenicity of hepatitis B vaccines in older adults. The sex difference may have biological underpinnings: androgens exert immunosuppressive effects, while estrogens appear to enhance immune and vaccine responses, potentially leaving men less able to clear or control the virus. The ethnic disparity points toward inequities in social determinants of health, including unequal access to vaccination, diagnosis, and treatment, a pattern consistent with prior Brazilian and international studies.

Cancer type itself was not independently associated with exposure, but subgroup patterns were striking. Among hematological malignancies, non-Hodgkin lymphoma showed a seroprevalence of 15.5 percent, a malignancy repeatedly linked to HBV in meta-analyses, though the mechanisms remain unresolved. Among solid tumors, the highest rates appeared in sarcoma, at 43.5 percent, a figure the authors caution may be inflated by small numbers, and in liver and bile duct cancers, at 31.2 percent. In adjusted analyses, liver and bile duct cancers carried more than threefold higher odds of HBV exposure, and gastrointestinal cancers carried 41 percent higher odds, findings consistent with the established oncogenic role of the virus, which operates through chronic hepatic inflammation, integration of viral DNA into the host genome, and the activity of viral proteins such as HBx.

Within the anti-HBc-positive group, additional testing of subsets clarified the virological picture. The hepatitis B surface antigen was positive in 7.8 percent of those tested, indicating current infection, while 73.2 percent carried anti-HBs antibodies consistent with resolved infection. Among 484 patients who underwent HBV DNA testing, 25.6 percent had detectable viral load. Taken together, most anti-HBc-positive patients showed evidence of past exposure, but a meaningful minority carried molecular or serological signs of active infection, underscoring why confirmatory testing matters before immunosuppressive therapy begins.

One encouraging operational trend accompanied the epidemiological one: the proportion of admitted patients screened for anti-HBc rose from 11.1 percent in 2010 to 29.2 percent in 2023. Even so, more than two-thirds of cancer patients admitted over the period were never tested, and global data suggest screening before chemotherapy reached only about 57 percent in pooled estimates, with uptake particularly weak among patients with solid tumors. The authors note that their retrospective, single-center design has limits, including incomplete medical records, unknown testing indications, and possible selection bias, and that treatment-related immunosuppression may have blunted antibody detectability in some patients. Still, the scale of the cohort and the length of the observation window lend weight to the conclusion. As vaccination coverage expands and screening becomes more systematic, the residual burden of HBV exposure among cancer patients should continue to shrink, provided that prevention reaches the demographic groups the data show are still being left behind.

Subject of Research: Temporal trends in hepatitis B virus seroprevalence among adult cancer patients in Brazil

Article Title: Trends in hepatitis B virus seroprevalence in a large cohort of adult cancer patients from 2010 to 2023

Article References: Rossi de Camargo Pinto, M., de Paula, V. G., Battaglia, D. B. R., de Oliveira, R., Ferreira, G. M., Manchiero, C., Dantas, B. P., Tengan, F. M., Abdala, E., & Magri, M. C. (2026). Trends in hepatitis B virus seroprevalence in a large cohort of adult cancer patients from 2010 to 2023. Cancer Causes & Control, 37(10), Article 178. https://doi.org/10.1007/s10552-026-02262-w

Image Credits: AI Generated

DOI: 10.1007/s10552-026-02262-w

Keywords: hepatitis B virus, seroprevalence, cancer patients, HBV reactivation, anti-HBc, temporal trends, vaccination, health disparities, hematological malignancies, solid tumors, oncology screening, Brazil