The study was conducted at Ankara Bilkent City Hospital, a tertiary referral center in Türkiye. Eligible patients were adults with histologically confirmed malignancy and a first abscess episode documented by contrast-enhanced cross-sectional imaging and a clinical diagnosis by the treating team. Percutaneous aspiration was performed in 177 patients, or 96.2% of the cohort; the other seven were diagnosed from imaging and clinical records. Culture positivity was not required, and only each patient’s first eligible episode was analyzed. Median age was 62 years, 107 participants, or 58.2%, were men, and 99, or 53.8%, had stage IV malignancy. Colorectal cancer was the most common diagnosis, followed by pancreatic cancer.

Abscesses occurred across multiple anatomical sites. The liver was involved in 73 patients, or 39.7% of the cohort, while 66 patients had non-hepatic intra-abdominal collections, 20 had retroperitoneal abscesses, 11 had thoracic or musculoskeletal collections, 10 had pelvic abscesses and four had abdominal-wall abscesses. Forty-two patients, or 22.8%, had multiple collections. The median recorded abscess diameter was 7.0 cm, with an interquartile range of 4.6–10.0 cm among 176 patients with available measurements. Therapeutic aspiration or drainage was performed in 173 patients, and 52 underwent two or more sessions. Median antibiotic duration was 16 days and median hospital stay was 32 days, although procedure outcomes and the adequacy of source control were not recorded.

An organism was recorded for 124 patients, or 67.4% of the cohort, with all isolates coming from percutaneous aspirates. Two clinicians independently reviewed every culture report and adjudicated possible contamination using the specimen type, organism identity, report wording and clinical record. After adjudication, 108 patients, or 58.7% of the full cohort, had at least one probable pathogen. Among these 108, 85, or 78.7%, had monomicrobial gram-negative growth; 16 had gram-positive pathogens, six had Candida albicans and one had a polymicrobial culture. Escherichia coli was identified in 43 patients and Klebsiella species in 29, including 27 K. pneumoniae isolates. Enterococci accounted for 10 probable pathogens and were proportionally more frequent in retroperitoneal and pelvic collections, while E. coli and K. pneumoniae together represented 74.5% of probable pathogens in hepatic abscesses.

Resistance was frequent among the 85 gram-negative isolates. Phenotypic extended-spectrum beta-lactamase, or ESBL, production was recorded in 38 of 80 tested Enterobacterales isolates, or 47.5%. It occurred in 28 of 43 E. coli isolates and eight of 27 K. pneumoniae isolates. Among the gram-negative pathogens, 55 were multidrug resistant and 14 extensively drug resistant, together accounting for 81.2%, or 69 of 85 isolates. Resistance exceeded 80% for ceftriaxone, ceftazidime, cefepime and amoxicillin–clavulanate. It was 65.7% for piperacillin–tazobactam, 62.3% for ciprofloxacin and 37.3% for ertapenem; resistance to at least one tested carbapenem was 35.2%. Amikacin, colistin and tigecycline retained activity against 84.6%, 86.4% and 100% of isolates tested, respectively.

These susceptibility results were descriptive and did not establish a preferred empirical antibiotic regimen. The researchers did not assess AmpC or carbapenemase production or confirm resistance mechanisms genetically, and the automated ESBL phenotype may misclassify some AmpC- or carbapenemase-producing isolates. The number of deaths also limited comparisons between resistance phenotypes. Moreover, the cohort came from one tertiary referral center, most cases were identified through oncology records and interventional radiology documentation, and patients managed conservatively or surgically may have been incompletely captured. The findings therefore describe resistance patterns in a selected local population rather than the full spectrum of cancer-associated abscesses.

Albumin was the strongest measured correlate of death during the first 90 days. The cohort’s median albumin was 3.0 g/dL, with an interquartile range of 2.7–3.5 g/dL. Values were obtained within the two days preceding the index date, defined as aspiration for 177 patients and first documentation for the seven who were not aspirated. In a Cox model adjusted for age and cancer stage and stratified by single versus multiple abscesses, a 0.5 g/dL higher albumin concentration was associated with a hazard ratio of 0.37 for 90-day mortality (95% CI, 0.26–0.53). The corresponding estimate was 0.14 per 1 g/dL. Stage IV disease and age were not statistically associated with mortality during this period. Model-based standardized 90-day mortality was estimated at 39.4% for albumin of 2.5 g/dL, 17.2% at 3.0 g/dL and 6.8% at 3.5 g/dL. The model-based risk difference between 2.5 and 3.5 g/dL was 32.5 percentage points, with a bootstrap 95% CI of 22.7–40.4.

The albumin association remained in sensitivity analyses that changed the time origin to first imaging or hospital admission, used a 30-day endpoint, excluded selected groups, or separately added variables related to severity, exposure, abscess site and microbiology. Adding intensive-care admission, vasopressor use, mechanical ventilation, C-reactive protein or procalcitonin did not eliminate the association. Albumin is a negative acute-phase reactant influenced by nutrition, tumor burden and systemic inflammation. Because it was measured during an established infection, the result most likely marked acute illness severity as well as nutritional and cancer-related factors rather than baseline host reserve alone. Performance status, formal sepsis scores, antimicrobial timing, source-control delay and detailed tumor burden were unavailable, leaving scope for residual confounding. The exploratory hemoglobin–albumin–lymphocyte–platelet score was not associated with 90-day mortality and discriminated outcomes less well than albumin in this cohort.

Longer follow-up indicated that early and later mortality had different correlates. Survival was 68.4% at 180 days and 54.3% at one year. The albumin association weakened as follow-up extended, with the hazard ratio per 1 g/dL changing from 0.14 during the first 90 days to 0.20 at 180 days, 0.25 at one year and 0.31 over all available follow-up. In a period-specific analysis, the corresponding hazard ratio after day 90 was 0.48. Stage IV disease followed the opposite pattern: its early hazard ratio was 0.70, with a wide confidence interval, while mortality after day 90 was more than twice as high among patients with stage IV disease, with a hazard ratio of 2.65 (95% CI, 1.45–4.84). One-year survival was 48.9% for stage IV patients and 60.9% for those with stage I–III disease. The early stage IV estimate should not be interpreted as protective because selecting patients who survived to abscess diagnosis may have introduced selection bias.

The findings remain provisional because the study was observational, retrospective and confined to one center, with heterogeneous abscess sites and no cancer control group without abscess. Cases were not formally adjudicated by radiologists, and imaging reports used the term “abscess” explicitly in only 35.5% of patients, leaving uncertainty around some collections. Ten patients were censored alive before day 90, antibiotic duration was incompletely documented for 28, and the database did not distinguish culture-negative episodes from those in which culture was never obtained. Death before aspiration could not enter the cohort, making survival estimates from earlier time origins susceptible to immortal time bias. The models were internally bootstrapped but not externally validated. Prospective multicenter studies with standardized imaging review, confirmatory resistance testing, detailed measures of sepsis severity and source control, and cause-specific mortality are needed to determine how broadly the albumin association and resistance patterns apply.

Subject of Research: Clinical, microbiological and prognostic features of imaging-confirmed abscesses in adults with malignancy

Article Title: Clinical and microbiological characteristics of abscesses in patients with malignancy and factors associated with 90-day mortality

Article References: Gencer, H., Kos, F. T., Guven, M., Calıskan, M., Ozberk, U., Bal, O., & Akinci, M. B. (2026). Clinical and microbiological characteristics of abscesses in patients with malignancy and factors associated with 90-day mortality. Frontiers in Cellular and Infection Microbiology, 16, 1969735. https://doi.org/10.3389/fcimb.2026.1969735

Image Credits: AI Generated

DOI: 10.3389/fcimb.2026.1969735

Keywords: cancer-associated abscesses, 90-day mortality, serum albumin, antimicrobial resistance, gram-negative bacteria, ESBL production, multidrug resistance, percutaneous aspiration, retrospective cohort, Clinical, microbiological, characteristics