The Incidence of Retained Objects in Intraoperative X-rays for Missing Counts in Plastic Surgery: We Should Do Better

Background

In the event of incorrect surgical counts, obtaining X-rays to rule out retained surgical items (RSI) is standard practice. However, these safeguards also carry risk. This study investigates the actual incidence of RSI in plastic reconstructive surgery (PRS) cases as measured on intraoperative X-rays and its associated modifiable risk factors.

Methods

X-rays with indication of "foreign body" in PRS procedures from 2012 to 2022 were obtained. Reports with "incorrect surgical counts" and associated perioperative records were retrospectively analyzed to determine the incidence of retained surgical items.

Results

Among 257 X-rays, 21.4% indicated incorrect counts during PRS operations. None were positive for RSIs. The average number of staff present was 12.01. This correlated to an average of 6.98 staff turnovers. The average case lasted 8.42 hours. X-rays prolonged the time under anesthesia by an average of 24.3 minutes. Free flap surgery had 49.1% prevalence of missing counts (lower extremity 25.5%, breast 20%, craniofacial 3.6%), followed by hand (14.5%), breast (10.9%), abdominal reconstruction (10.9%), craniofacial (9.1%), and cosmetic (5.4%).

Conclusions

Although X-rays for incorrect counts intend to prevent catastrophic sequela of inadvertent RSIs, our results suggest the true incidence of RSI in PRS is negligible. However, intraoperative X-rays have potentially detrimental and pervasive consequences for patients, including increased anesthesia time, radiation exposure, and higher overall cost. Addressing modifiable risk factors to minimize unnecessary intraoperative X-rays is imperative while also considering whether this modality is an effective and appropriate tool in PRS procedures with incorrect surgical counts.

Healing Exposed Calvarial Hardware Using Negative-Pressure Wound Therapy and Vashe Wound Solution: Case Report

OBJECTIVE

The management of cranioplasty infections has historically been explantation followed by delayed reimplantation/reconstruction. This treatment algorithm necessitates surgery, tissue expansion, and prolonged disfigurement. In this report, the authors describe a treatment approach consisting of serial vacuum-assisted closure (VAC) with hypochlorous acid (HOCl) solution (Vashe Wound Solution; URGO Medical) as a salvage strategy.

METHODS

A 35-year-old man who sustained head trauma, neurosurgical complications, and severe syndrome of the trephined (SOT; devastating neurologic decline treated by cranioplasty) underwent titanium cranioplasty with free flap. Three weeks postoperation, he presented with pressure-related wound dehiscence/partial flap necrosis, exposed hardware, and bacterial infection. Given the severity of his precranioplasty SOT, hardware salvage was critical. He was treated with serial VAC with HOCl solution for 11 days followed by VAC for 18 days and definitive split-thickness skin graft placement over resulting granulation tissue. Authors also conducted a literature review of cranial reconstruction infection management.

RESULTS

The patient remained healed 7 months postoperatively without recurrent infection. Importantly, his original hardware was retained, and his SOT remained resolved. Findings from the literature review support the use of conservative modalities to salvage cranial reconstructions without hardware removal.

CONCLUSIONS

This study investigates a new strategy for managing cranioplasty infections. The VAC with HOCl solution regimen was effective in treating the infection and salvaging the cranioplasty, thus obviating the complications associated with explantation, new cranioplasty, and recurrence of SOT. There is limited literature on the management of cranioplasty infections using conservative treatments. A larger study to better determine the efficacy of VAC with HOCl solution is underway.

Closed Incision Negative Pressure Therapy in Oncoplastic Surgery Prevents Delays to Adjuvant Therapy

Breast reductions, including oncoplastic breast surgery (OBS), have high postoperative wound healing complication (WHC) rates, ranging from 17% to 63%, thus posing a potential delay in the onset of adjuvant therapy. Incision management with closed incision negative pressure therapy (ciNPT) effectively reduces postoperative complications in other indications. This retrospective analysis compares postoperative outcomes and delays in adjuvant therapy in patients who received ciNPT on the cancer breast versus standard of care (SOC) after oncoplastic breast reduction and mastopexy post lumpectomy.

Methods

Patient demographics, ciNPT use, postoperative complication rates, and time to adjuvant therapy were analyzed from the records of 150 patients (ciNPT = 29, SOC = 121). Propensity score matching was used to match patients based on age, body mass index, diabetes, tobacco use, and prior breast surgery.

Results

In the matched cohort, the overall complication rate of ciNPT-treated cancerous breasts was 10.3% (3/29) compared with 31% (9/29) in SOC-treated cancerous breasts (P = 0.096). Compared with the SOC-treated cancerous breasts, the ciNPT breasts had lower skin necrosis rates [1/29 (3.4%) versus 6/29 (20.7%); P = 0.091] and dehiscence rates [0/29 (0%) versus 8/29 (27.6%); P = 0.004]. In the unmatched cohort, the total number of ciNPT patients who had a delay in adjuvant therapy was lower compared to the SOC group (0% versus 22.5%, respectively; P = 0.007).

Conclusion

Use of ciNPT following oncoplastic breast reduction effectively lowered postoperative wound healing complication rates and, most importantly, decreased delays to adjuvant therapy.

In vivo CRISPR screens reveal the landscape of immune evasion pathways across cancer

The immune system can eliminate tumors, but checkpoints enable immune escape. Here, we identify immune evasion mechanisms using genome-scale in vivo CRISPR screens across cancer models treated with immune checkpoint blockade (ICB). We identify immune evasion genes and important immune inhibitory checkpoints conserved across cancers, including the non-classical major histocompatibility complex class I (MHC class I) molecule Qa-1b/HLA-E. Surprisingly, loss of tumor interferon-γ (IFNγ) signaling sensitizes many models to immunity. The immune inhibitory effects of tumor IFN sensing are mediated through two mechanisms. First, tumor upregulation of classical MHC class I inhibits natural killer cells. Second, IFN-induced expression of Qa-1b inhibits CD8+ T cells via the NKG2A/CD94 receptor, which is induced by ICB. Finally, we show that strong IFN signatures are associated with poor response to ICB in individuals with renal cell carcinoma or melanoma. This study reveals that IFN-mediated upregulation of classical and non-classical MHC class I inhibitory checkpoints can facilitate immune escape.

Abstract 3610: In vivo CRISPR screens reveal the landscape of immune evasion pathways across cancer

The immune system can eliminate tumors, but checkpoints enable tumors to escape immune destruction. Here, we report the systematic identification of immune evasion mechanisms using genome-scale in vivo CRISPR screens in eight murine cancer models treated with immune checkpoint blockade (ICB). We identify and validate previously unreported immune evasion genes and identify key immune inhibitory checkpoints that have a conserved role across several cancer models, such as the non-classical MHC-I molecule Qa-1b/HLA-E, which scores as the top overall sensitizing hit across all screens. Surprisingly, we find that loss of IFNγ signaling by tumor cells sensitizes 6 of 8 cancer models to ICB. While IFN-mediated inflammation has been associated with response to ICB, there have also been reports of ICB-resistance driven by IFN sensing. However, several divergent mechanisms have been proposed to explain the inhibitory effect of tumor IFN sensing, leading to uncertainty about how this key immune signaling pathway is regulating anti-tumor immunity in different contexts. Using in vivo screening data, transcriptional profiling, and genetic interaction studies, we reveal that the immune-inhibitory effects of tumor IFN sensing are the direct result of tumor upregulation of classical and non-classical MHC-I genes. The interferon-MHC-I axis can inhibit anti-tumor immunity through two mechanisms: first, upregulation of classical MHC-I inhibits the cytotoxicity of natural killer cells, which are activated by ICB. Second, IFN-mediated upregulation of Qa-1b directly inhibits cytotoxicity by effector CD8+ T cells via the NKG2A/CD94 receptor, which is induced on CD8+ T cells by ICB. Finally, we show that high interferon-stimulated gene expression in patients is associated with decreased survival in RCC and poor response to ICB in melanoma. Our study establishes a unifying mechanism to explain the inhibitory role of tumor IFN sensing, revealing that IFN-mediated upregulation of classical and non-classical MHC-I inhibitory checkpoints can facilitate immune escape.

Citation Format: Juan Dubrot, Peter P. Du, Sarah Kate Lane-Reticker, Emily A. Kessler, Audrey J. Muscato, Arnav Mehta, Samuel S. Freeman, Peter M. Allen, Kira E. Olander, Kyle M. Ockerman, Clara H. Wolfe, Fabius Wiesmann, Nelson H. Knudsen, Hsiao-Wei Tsao, Arvin Iracheta-Vellve, Emily M. Schneider, Andrea N. Rivera-Rosario, Ian C. Kohnle, Hans W. Pope, Austin Ayer, Gargi Mishra, Margaret D. Zimmer, Sarah Y. Kim, Animesh Mahapatra, Hakimeh Ebrahimi-Nik, Dennie T. Frederick, Genevieve M. Boland, W. Nicholas Haining, David E. Root, John G. Doench, Nir Hacohen, Kathleen B. Yates, Robert T. Manguso. In vivo CRISPR screens reveal the landscape of immune evasion pathways across cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3610.

In vivo screens using a selective CRISPR antigen removal lentiviral vector system reveal immune dependencies in renal cell carcinoma

CRISPR-Cas9 genome engineering has increased the pace of discovery for immunology and cancer biology, revealing potential therapeutic targets and providing insight into mechanisms underlying resistance to immunotherapy. However, endogenous immune recognition of Cas9 has limited the applicability of CRISPR technologies in vivo. Here, we characterized immune responses against Cas9 and other expressed CRISPR vector components that cause antigen-specific tumor rejection in several mouse cancer models. To avoid unwanted immune recognition, we designed a lentiviral vector system that allowed selective CRISPR antigen removal (SCAR) from tumor cells. The SCAR system reversed immune-mediated rejection of CRISPR-modified tumor cells in vivo and enabled high-throughput genetic screens in previously intractable models. A pooled in vivo screen using SCAR in a CRISPR-antigen-sensitive renal cell carcinoma revealed resistance pathways associated with autophagy and major histocompatibility complex class I (MHC class I) expression. Thus, SCAR presents a resource that enables CRISPR-based studies of tumor-immune interactions and prevents unwanted immune recognition of genetically engineered cells, with implications for clinical applications.