Epidemiological characteristics and non-linear risk factors of surgical site infections in patients with cancer: a...

Surgical site infection (SSI) imposes a significant burden on patients with cancer, yet comprehensive studies on the cancer-specific SSI remain limited.

A case-control study analysed SSI epidemiology in 20,370 cancer patients who underwent surgery at a specialized hospital in Shandong Province, China, between 2021 and 2023, using propensity score matching (PSM) to adjust for confounders. Multi-variable conditional logistic regression and restricted cubic splines (RCS) were used to identify risk factors and non-linear associations.

SSI incidence was 1.23%, predominating in males, class II wounds, organ/space SSI, and colorectal surgery. Microbiological testing recovered 277 pathogens, mainly Gram-negative bacteria (67.1%). Gram-negative isolates showed high resistance to ampicillin and cephalosporins, while carbapenems and amikacin remained effective. Independent risk factors were body mass index (BMI) (adjusted odds ratio [aOR]: 1.090), postoperative antibiotic therapy (aOR: 3.662), and prolonged postoperative antibiotic therapy (aOR: 1.214). Protective factors included extended pre-operative antibiotic therapy on the day of surgery (aOR: 0.958) and elective surgery (aOR: 0.325). A non-linear relationship appeared between SSI risk and pre-operative white blood cell (WBC) counts. SSI risk increased linearly with BMI above 25 kg/m² and operative time exceeding 161 min.

In cancer patients, SSI is mainly caused by Gram-negative bacteria resistant to ampicillin and cephalosporins. Risk factors included higher BMI, prolonged surgery, and postoperative antibiotic use, whereas pre-operative antibiotic therapy on the day of surgery and elective surgery was protective. A non-linear relationship was observed between SSI risk and pre-operative WBC counts. These findings inform prevention strategies but require validation in multi-centre prospective studies.