A 5-day postoperative course of antibiotics is not superior to a 1-day course for preventing surgical site infections in patients with lower extremity bone tumors, according to results from the PARITY trial published in JAMA Oncology.

The PARITY study (ClinicalTrials.gov Identifier: NCT01479283) included 604 patients with primary bone tumors, soft tissue sarcomas invading the femur or tibia, or oligometastatic bone disease of the femur or tibia who required surgery and endoprosthetic reconstruction. The mean age was 41 years, 59.8% were men, and 63.8% were White.

Patients were randomly assigned to receive either a 5-day regimen of intravenous cephalosporin (293 patients) or a 1-day regimen of the same (311 patients), with the primary outcome being surgical site infection.

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There were no significant differences between the treatment groups in rates of surgical site infections, unplanned operations, oncologic events, or all-cause mortality. However, there was a difference in antibiotic-related complications.

The rate of surgical site infection was 15% on the 5-day regimen and 16.7% on the 1-day regimen (hazard ratio [HR], 0.93; 95% CI, 0.62-1.40; P =.73). Unplanned additional operations occurred in 25.6% and 25.7% of patients, respectively (HR, 1.06; 95% CI, 0.77-1.46; P =.72).

Oncologic events occurred in 29% of patients on the 5-day regimen and 28.6% of those on the 1-day regimen (HR, 1.02; 95% CI, 0.75-1.39; P =.90). The all-cause mortality rate was 12.6% and 12.9%, respectively (HR, 1.01; 95% CI, 0.64-1.58; P =.98).

The rate of complications was 5.1% with the 5-day regimen and 1.6% with the 1-day regimen (HR, 3.24; 95% CI, 1.17-8.98; P =.02). Colitis related to Clostridioides difficile was the most common such complication, affecting 3.8% of the 5-day group and 1.3% of the 1-day group.

The researchers acknowledged that this study may have been underpowered, and that might explain the lack of a statistically significant difference in surgical site infections between the groups.

“However, the observed absolute difference between the two treatment groups was small, and the increased sample size needed to show statistical significance would likely not be considered necessary by surgeons in the field,” they wrote.

The researchers added that, although the study does not conclusively exclude a benefit from lengthier antibiotic treatments, the observed higher risk of antibiotic-related complications with the 5-day regimen should inform clinicians’ treatment decisions. 

Disclosures: This research was supported by government grants, various organizations, and private donors. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Ghert M, Schneider P, Guyatt G, et al. Comparison of prophylactic intravenous antibiotic regimens after endoprosthetic reconstruction for lower extremity bone tumors. JAMA Oncol. Published online January 6, 2022. doi:10.1001/jamaoncol.2021.6628