Plate Nº 73 · recorded October 10, 2026
Health & Medicine ResearchReported finding
One in Four Pneumonia Patients Had a Blood Cancer Marker
A Swedish study of 156 hospitalized patients found one in four carried a blood cancer marker, and screening led to 7 cancer diagnoses and 8 immunodeficiency cases.
By Elena Vasquez3 min read699 words
In brief
- One in four of 156 patients hospitalized with invasive pneumococcal disease in Sweden (2018–2023) had M protein, a blood cancer risk marker.
- Screening led to 7 blood cancer diagnoses, 12 precursor conditions, and 8 immunodeficiency cases; 7 patients started preventive treatment.
- The median patient age was 70; the control group had 64 age- and sex-matched individuals.
- The study was published in Scientific Reports (2026), DOI: 10.1038/s41598-026-61992-8.
- Vaccine-covered pneumococcal serotypes dropped sharply after Sweden's childhood vaccination program but were replaced by unprotected serotypes.
One in four adults hospitalized with severe pneumococcal disease carried M protein in their blood — a marker that can signal blood cancer or a precursor condition — according to a study from the University of Gothenburg published in Scientific Reports.
The findings come from 156 patients treated in Region Västra Götaland, Sweden, between 2018 and 2023, all of whom had invasive pneumococcal disease, most commonly pneumonia. Their median age was 70 years.
The follow-up examinations had real clinical consequences. Doctors diagnosed seven patients with blood cancer. Another 12 received a diagnosis of a condition that can, in some cases, progress to blood cancer. Eight patients turned out to have immunodeficiency — a weakened immune system — and seven of them were able to start preventive treatment against new, severe infections.
What did the researchers actually measure?
The research team, led by doctoral students Tor Härnqvist and Karin Bergman, took a straightforward approach. They measured antibody levels — the infection-fighting proteins the immune system produces — in the hospitalized patients. They also tested for M protein, a molecule that appears in blood cancer and in precursor conditions that may develop into it.
To put the results in context, the researchers compared the patients with a control group of 64 individuals matched for age and sex who had not had invasive pneumococcal disease. Both the M protein findings and the immune deficiencies were considerably less common in that comparison group.
Pneumococcal disease is caused by Streptococcus pneumoniae bacteria. When these bacteria invade normally sterile parts of the body, such as the bloodstream, they cause what doctors call "invasive" disease — a category that includes severe pneumonia requiring hospital care.
Why can pneumonia reveal hidden cancer?
The connection runs through the immune system. Blood cancers and immunodeficiencies can weaken the body's defenses, making severe bacterial infections more likely. In other words, the infection is sometimes the first visible sign of an underlying problem that had gone unnoticed.
That raises a practical question: should every adult hospitalized with invasive pneumococcal disease be screened for M protein and antibody levels? The researchers believe such screening deserves serious consideration.
"Currently, these tests are not routinely performed after a severe pneumococcal infection," says Tor Härnqvist, a doctoral student at the University of Gothenburg and an infectious disease physician at NU Hospital Group. "As a result, we may miss patients with undiagnosed blood cancer or immunodeficiency and therefore miss the opportunity to initiate treatment."
What about vaccination?
The study forms part of Karin Bergman's doctoral thesis, which she will soon defend at the University of Gothenburg. Her thesis work also tracks how the pneumococcal bacteria causing severe disease have changed since the pneumococcal vaccine entered the Swedish childhood vaccination program.
The picture that emerges is one of bacterial replacement. Serotypes — distinct bacterial variants — covered by the childhood vaccine have decreased sharply. But other serotypes, against which that vaccine offers no protection, have largely taken their place. Older adults and people with underlying conditions, particularly cancer and compromised immune systems, are frequently affected by these replacement serotypes.
That shift has policy implications for adult vaccination.
"The results show that recommendations on pneumococcal vaccines for adults need to take into account which vaccines are used in children and which bacterial serotypes subsequently circulate in the community," Bergman said.
How firm are the findings?
Some caution is warranted. The study followed 156 patients in a single Swedish region over five years, and the results come from a prospective observational design rather than a randomized trial. A finding that M protein is present does not mean every carrier has cancer — the marker can appear in precursor conditions that only sometimes progress.
Still, the study shows that a severe pneumococcal infection can serve as a clinical alarm bell. Seven cancer diagnoses, twelve precursor conditions, and eight cases of immunodeficiency emerged from the examinations — conditions that, on the researchers' own account, would likely have gone unnoticed without systematic testing.
Whether routine screening should follow is now a question for health authorities. The study is published as Tor Härnqvist et al., "Invasive pneumococcal disease unmasks monoclonal immunoglobulins and antibody deficiencies: a multicenter prospective study in adults," Scientific Reports (2026), DOI: 10.1038/s41598-026-61992-8.
via Medical Xpress (Source)
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