Prognostic value of a mandibular canal staging system for primary lesions in patients with lower gingival squamous cell carcinoma: a multicenter, retrospective study.

BACKGROUND: The Union for International Cancer Control and American Joint Committee on Cancer tumor staging system is used globally for treatment planning. As it may be insufficient for tumor staging of lower gingival carcinomas, we proposed the mandibular canal tumor staging system. In this study, we aimed to compare the two systems for such tumor staging and to identify prognostic markers. METHODS: This multicenter, retrospective study included patients with lower gingival squamous cell carcinoma who underwent radical surgery during 2001-2018. We compared survival rates (Kaplan-Meier estimator) and patient stratification according to the two systems. RESULTS: The proposed system yielded more balanced patient stratification than the existing system. Progression in the tumor grade according to the proposed system was associated with a poorer prognosis. The 5-year overall and disease-specific survival rates for the entire cohort were 74.9% and 81.8%, respectively. Independent factors affecting overall survival were tumor stage according to the proposed system, excision margins, and number of positive nodes, whereas those affecting disease-specific survival were excision margins and number of positive nodes. CONCLUSIONS: Subsite-specific tumor classification should be used for patients with oral cancer, and our results suggest that mandibular canal tumor classification may be effective for patients with lower gingival carcinoma.

Dental and oral management in the perioperative period of surgery: A scoping review.

Dental and oral management (DOM) is a long-established treatment modality. This scoping review aimed to narratively review previous studies, examine the effects of perioperative DOM, and identify the available evidence. A literature search was conducted using the PubMed electronic database for studies published between January 1, 2000, and March 8, 2022. The search yielded 43 studies, most of which were published in the last 10 years. The results of this study confirmed that improved perioperative oral hygiene is effective in preventing postoperative pneumonia. Our results also suggested that preoperative DOM is effective in preventing postoperative surgical site infections. Perioperative DOM is effective in reducing the incidence of postoperative pneumonia, SSI, and postsurgical complications. Further studies are needed to elucidate the various mechanism of DOM and to examine efficient intervention methods and timing.

Efficacy of perioperative oral care management in the prevention of surgical complications in 503 patients after pancreaticoduodenectomy for resectable malignant tumor: A multicenter retrospective analysis using propensity score matching.

BACKGROUND: Pancreaticoduodenectomy has been associated with a high mortality rate and significant postoperative morbidity. Recently, perioperative oral care management has been reported to be effective in preventing postoperative pneumonia and surgical site infection. In this study, we examined the effect of perioperative oral care management in reducing complications after pancreaticoduodenectomy, including surgical site infection. METHODS: This retrospective multicenter study included 503 patients who underwent pancreaticoduodenectomy at 8 facilities between January 2014 and December 2016. Among these, 144 received perioperative oral management by dentists and dental hygienists (oral management group), whereas the remaining 359 did not (control group). The oral care management program included oral health instructions, removal of dental calculus, professional mechanical tooth cleaning, removal of tongue coating, denture cleaning, instructions for gargling, and tooth extraction. The participants were matched using propensity scores to reduce background bias. Various factors were examined for correlation with the development of complications. RESULTS: The incidence of organ/space surgical site infection was significantly lower in the oral management group than in the control group (8.0% vs 19.6%, P = .005). Multivariable logistic regression analysis revealed that hypertension and lack of perioperative oral management were independent risk factors for organ/space surgical site infection. Lack of perioperative oral management had an odds ratio of 2.847 (95% confidence interval 1.335-6.071, P = .007). CONCLUSION: Perioperative oral care management reduces the occurrence of surgical site infections after pancreaticoduodenectomy and should be recommended as a strategy to prevent infections in addition to antibiotic use.

Is withdrawal of antiresorptive agents necessary before and after tooth extraction? A systematic review.

OBJECTIVES: The need for prevention and management of medication-related osteonecrosis of the jaw (MRONJ) has increased with the growing number of patients using antiresorptive agents. The scope of this systematic review (SR) was to determine whether the withdrawal of antiresorptive agents is necessary for tooth extractions in patients receiving each of the antiresorptive medications. MATERIALS AND METHODS: The searches were performed using the MEDLINE databases. We selected SRs, randomized controlled trials (RCTs), prospective and retrospective non-randomized clinical (observational) studies, and case reports/case series in this order of preference. RESULTS: We included one SR, one RCT, five observational studies, and three case reports. Meta-analyses were not conducted because the RCT had an extremely small sample size and the observational studies had different definitions of intervention and comparison that could not be integrated across studies. In this SR, no studies showed a benefit (i.e., a reduction in the incidence of osteonecrosis of the jaw) of short-term withdrawal of antiresorptive agents for tooth extraction. Additionally, no studies examined the harm (i.e., an increase in femoral and vertebral fractures and skeletal-related events during bone metastasis) of withdrawal for tooth extraction. CONCLUSIONS: We were unable to determine whether withdrawal before and after tooth extraction is necessary with a high certainty of evidence. Future systematic reviews including RCTs with larger samples are expected to provide such evidence. CLINICAL RELEVANCE: This systematic review provides evidence-based information for multidisciplinary collaborations related to patients receiving antiresorptive agents.

Complete Response to Cetuximab Plus Paclitaxel Therapy in Nivolumab-Refractory Patients in Distant Metastasis of Squamous Cell Carcinoma of the Tongue: A Report of Two Cases.

Herein, we report two cases of patients diagnosed with nivolumab-refractory distant metastatic squamous cell carcinoma of the tongue who were successfully treated with a combination of paclitaxel and cetuximab. Case 1 had controllable local recurrence and distant metastasis. Case 2 had controllable distant metastatic disease. Thus, demonstrating that some nivolumab-refractory patients with recurrent or distant metastatic oral squamous cell carcinoma may benefit from subsequent salvage chemotherapy.

Comparison of the 8th edition of TNM staging of oral cancer with the 7th edition and its prognostic significance using clinical depth of invasion and extranodal extension.

OBJECTIVES: The 8th edition of the International Union Against Cancer Control/American Joint Committee on Cancer Staging System introduced depth of invasion (DOI) and extranodal extension (ENE) into the staging of oral cavity cancer. We evaluated the prognostic ability of this new staging system compared with the 7th edition using clinical DOI (cDOI) and clinical ENE (cENE). MATERIALS AND METHODS: We retrospectively reviewed and restaged 2,118 patients with oral squamous cell carcinoma treated between 2001 and 2018 using cDOI and cENE. Overall and disease-specific survival were used as endpoints to compare the prognostic outcomes of the 7th and 8th editions using Harrell's concordance index (C-index). RESULTS: In total, 305 (14.4 %) cases were upstaged in the T category, 85 (4.0 %) cases were upstaged in the N category, and 280 (13.2 %) cases were upstaged in the overall TNM stage. The introduction of the cDOI increased the C-index and hazard ratio (HR) for each T category. The introduction of cENE increased the N3b category of 85 cases, bringing the total to 94 cases, thereby widening the differences between each N category. In the 8th edition, the C-index and HR for overall TNM stage increased, and the discrimination between stage groups improved. CONCLUSIONS: The 8th edition of the TNM clinical staging system using cDOI and cENE predominantly identified patients with a high mortality rate, thus improving the ability to discriminate and prognosticate oral cancer.

Neutrophil-to-lymphocyte ratio as an early marker of outcomes in patients with recurrent oral squamous cell carcinoma treated with nivolumab.

The immune checkpoint inhibitor (ICI), nivolumab, has revolutionised the treatment of recurrent and metastatic oral cancer. However, the response rate to ICIs remains low, and identifying predictors of nivolumab response is critical. Although the neutrophil-to-lymphocyte ratio (NLR) has been suggested as a predictive marker of nivolumab response in patients with various types of cancer, its utility in oral squamous cell carcinoma (OSCC) has not been elucidated. In this retrospective multicentre cohort study, we evaluated the association between NLR and outcome of nivolumab treatment in 64 patients with OSCC treated between 2017 and 2020. The objective response and disease control rates were 25.1% and 32.9%, respectively. The rates for complete and partial responses were 15.7% (10/64) and 9.4% (6/64), respectively; stable and progressive disease rates were 7.8% (5/64) and 67.1% (43/64), respectively. Complete and partial responses were classified as responders, and stable and progressive diseases were classified as non-responders. The median (range) pre-treatment NLR among responders was 4.3 (2.8-8.0), which decreased to 4.0 (2.6-6.3) after nivolumab treatment, and the median (range) pre-treatment NLR among non-responders was 5.1 (2.7-7.9), which increased to 6.4 (4.0-14.0) with tumour growth. Moreover, overall survival was significantly worse in the group with a higher post-treatment NLR (≥5) than in the group with a lower NLR (<5). Patients with a post-treatment NLR of ≥6 had worse outcomes for salvage chemotherapy following nivolumab treatment. Thus, post-treatment NLR could be a useful marker for predicting the response to nivolumab treatment or salvage chemotherapy in patients with OSCC.

Radiotherapy Plus Cetuximab for Squamous Cell Carcinoma of the Oral Cavity: A Multicenter Retrospective Study of 79 Patients in Japan.

There are a few reports that focus on radiotherapy (RT) and cetuximab (CET) therapy exclusively for oral cancer. This retrospective study aimed to investigate the efficacy and safety of RT and CET therapy for locally advanced (LA) or recurrent/metastatic (R/M) oral squamous cell carcinoma (OSCC). Seventy-nine patients from 13 hospitals who underwent RT and CET therapy for LA or R/M OSCC between January 2013 and May 2015 were enrolled in the study. Response, overall survival (OS), disease-specific survival (DSS), and adverse events were investigated. The completion rate was 62/79 (78.5%). The response rates in patients with LA and R/M OSCC were 69% and 37.8%, respectively. When only completed cases were examined, the response rates were 72.2% and 62.9%, respectively. The 1- and 2-year OS were 51.5% and 27.8%, respectively (median, 14 months), for patients with LA OSCC, and 41.5% and 11.9% (median, 10 months) for patients with R/M OSCC. The 1- and 2-year DSS were 61.8% and 33.4%, respectively (median, 17 months), for patients with LA OSCC, and 76.6% and 20.4% (median, 12 months) for patients with R/M OSCC. The most common adverse event was oral mucositis (60.8%), followed by dermatitis, acneiform rash, and paronychia. The completion rate was 85.7% in LA patients and 70.3% in R/M patients. The most common reason for noncompletion was an inadequate radiation dose due to worsening general conditions in R/M patients. Although the standard treatment for LA or R/M oral cancer is concomitant RT with high-dose cisplatin (CCRT) and the efficacy of RT and CET therapy for oral cancer is not considered to be as high as that for other head and neck cancers, it was thought that RT and CET therapy could be possible treatments for patients who cannot use high-dose cisplatin.

Multicenter retrospective study of the prognosis and the effect of postoperative adjuvant therapy in Japanese oral squamous cell carcinoma patients with close margin.

BACKGROUND: The purpose of this retrospective study was to investigate the prognosis of patients with oral cavity cancer with positive margin (PM) or close margin (CM) divided into pN- and pN+ groups. METHODS: The evaluated endpoints were local control and disease-specific survival (DSS) rates. RESULTS: Higher T classification, lymphovascular space invasion (LVSI), and older age were significant risk factors for DSS in the pN- groups. On the other hand, extranodal extension, multiple lymph node metastases, and LVSI were significant risk factors for DSS in the pN+ groups. Among the CM pN+ patients, no significant differences in the 3-year DSS were observed between the only surgery (51.9%) and adjuvant groups (53.2%). CONCLUSIONS: Higher T classification and LVSI are high-risk features more than PM or CM in the pN- groups for DSS. However, further prospective studies are needed to demonstrate the usefulness of adjuvant treatment in patients with PM or CM.

The Impact of Pretreatment Low Body Mass Index on Cause-Specific Mortality in Patients with Squamous Cell Carcinoma of the Oral Cavity.

The association between the pretreatment body mass index (BMI) and oral squamous cell carcinoma (SCC) outcomes is controversial. We aimed to examine the association between BMI and cause-specific mortality due to cancer of the oral cavity and patterns of failure that correlate with increased mortality. We enrolled 2,023 East Asian patients in this multicenter cohort study. We used the cumulative incidence competing risks method and the Fine-Gray model to analyze factors associated with cause-specific mortality, local recurrence, regional metastasis, and distant metastasis as first events. The median follow-up period was 62 mo. The 5-year cause-specific mortality for patients with underweight was 25.7%, which was significantly higher than that for patients with normal weight (12.7%, P < 0.0001). The multivariate model revealed that underweight was an independent risk factor for cause-specific mortality and regional metastasis (P < 0.05). Moreover, patients with underweight displayed a 51% and 55% increased risk of cause-specific mortality and regional metastasis, respectively, compared with their normal weight counterparts. Local recurrence was not associated with the BMI categories; however, the incidence of distant metastasis inversely decreased with BMI value. In summary, being underweight at diagnosis should be considered a high-risk mortality factor for oral SCC.

A Multicenter Study on the Effect of Margin Distance on Survival and Local Control in Stage 1-2 Squamous Cell Carcinoma of the Tongue.

BACKGROUND: Pathological close margins are considered a significant factor for local recurrence in patients with oral cancer. However, the oral cavity has complicated anatomical features, and the appropriate margin distance for each site is unknown. This multicenter, retrospective study aimed to determine the appropriate resection margin for early tongue cancer and investigate the need for additional treatment for close margins and stump dysplasia. PATIENTS AND METHODS: In total, 564 patients from ten hospitals were enrolled in this study. Sex, age, performance status, T stage, tumor length diameter, depth of invasion, elective neck dissection, iodine staining, horizontal margin distance, vertical margin distance, pathological differentiation, invasion pattern, lymphatic invasion, perineural invasion, dysplasia in the resection edge, additional treatment for close margins, local recurrence, neck metastasis, distant metastasis, and outcomes were investigated. RESULTS: Receiver operating characteristic analysis for local recurrence revealed cut-off values of 3.3 mm for horizontal distance and 3.1 mm for vertical distance. Patients with close horizontal or vertical margins showed significantly higher local recurrence rates, but these were not associated with overall or disease-specific survival. Furthermore, there was no effect of additional treatment in patients with dysplasia at the surgical margin. CONCLUSION: For early tongue cancer, a horizontal margin of 3.3 mm was defined as a close margin. Close margins were significantly correlated with local recurrence but did not affect survival. In the future, we would like to examine the concept of "quality margins," including the surrounding anatomical features.

Protocol for a multicentre, prospective observational study of elective neck dissection for clinically node-negative oral tongue squamous cell carcinoma (END-TC study).

INTRODUCTION: In early-stage oral tongue squamous cell carcinoma (OTSCC), elective neck dissection (END) is recommended when occult lymph node metastasis is suspected; however, there is no unanimous consensus on the risks and benefits of END in such cases. The management of clinically node-negative (cN0) OTSCC remains controversial. This study, therefore, aimed to evaluate the efficacy of END and its impact on the quality of life (QoL) of patients with cN0 OTSCC. METHODS AND ANALYSIS: This is a prospective, multicentre, nonrandomised observational study. The choice of whether to perform END at the same time as resection of the primary tumour is based on institutional policy and patient preference. The primary endpoint of this study is 3-year overall survival. The secondary endpoints are 3-year disease-specific survival, 3-year relapse-free survival and the impact on patient QoL. Propensity score-matching analysis will be performed to reduce selection bias. ETHICS AND DISSEMINATION: This study was approved by the Clinical Research Review Board of the Nagasaki University. The protocol of this study was registered at the University Hospital Medical Information Network Clinical Trials Registry. The datasets generated during the current study will be available from the corresponding author on reasonable request. The results will be disseminated internationally, through scientific and professional conferences and in peer-reviewed medical journals. TRIAL REGISTRATION NUMBER: UMIN000027875.

Prevalence of and risk factors for postoperative complications after lower third molar extraction: A multicenter prospective observational study in Japan.

Lower third molar extraction is the most common surgical treatment among routine dental and oral surgical procedures. while the surgical procedures for lower third molar extraction are well established, the difficulty of tooth extraction and the frequency of postoperative complications differ depending on the patient's background. To establish a management protocol for the lower third molars, the prevalence of and risk factors for postoperative complications after lower third molar extraction were investigated in a large number of Japanese patients in a multicenter prospective study. During 6 consecutive months in 2020, 1826 lower third molar extractions were performed at the 20 participating institutions. The medical records of the patients were reviewed, and relevant data were extracted. The prevalence of and risk factors for postoperative complications were analyzed. The prevalence of postoperative complications after lower third molar extraction was 10.0%. Multivariate analysis indicated that age (≤32 vs >32, odds ratio [OR]: 1.428, 95% confidence interval [95% CI]: 1.040-1.962, P < .05), the radiographic anatomical relationship between the tooth roots and mandibular canal (overlapping of the roots and canal vs no close anatomical relationship between the roots and the superior border of the canal, OR: 2.078, 95% CI: 1.333-3.238, P < .01; overlapping of the roots and canal vs roots impinging on the superior border of the canal, OR: 1.599, 95% CI: 1.050-2.435, P < .05), and impaction depth according to the Pell and Gregory classification (position C vs position A, OR: 3.7622, 95% CI: 2.079-6.310, P < .001; position C vs position B, OR: 2.574, 95% CI: 1.574-4.210, P < .001) are significant independent risk factors for postoperative complications after lower third molar extraction. These results suggested that higher age and a deeply impacted tooth might be significant independent risk factors for postoperative complications after lower third molar extraction.

Treatment and Prognosis of Oral Cancer Patients with Confirmed Contralateral Neck Metastasis: A Multicenter Retrospective Analysis.

The prognosis of oral cancer that has metastasized to the contralateral cervical lymph nodes is poor, although the appropriate treatment method has not been established because of its rarity. A multicenter retrospective study on the treatment and prognosis of pN2c oral cancer patients was conducted. We investigated the treatment and prognosis of 62 pN2c patients out of 388 pN+ patients with oral squamous cell carcinomas. Statistical analysis was performed on the various factors with overall survival (OS) and disease specific survival (DSS). In multivariate cox regression analysis, advanced T stage was significantly correlated with poor OS (p = 0.011) and DSS (p = 0.023) of patients with pN2c neck. In pN2c patients, OS, DSS, and neck control was not different between those undergoing ipsilateral neck dissection initially and those undergoing bilateral neck dissection. Thus, contralateral elective neck dissection is not recommended. The most important risk factor for prognosis in pN2c oral cancer patients is advanced T stage. No evidence was found to recommend contralateral elective neck dissection in clinically N1/2b patients. Therefore, the indication for contralateral elective neck dissection in N1/2b patients should be carefully determined in consideration of individual conditions.

Oral melanoma: a multicenter study of 69 patients from Japan.

OBJECTIVES: The purpose of this multicenter retrospective study was to investigate the demographic characteristics and treatment outcomes of patients with mucosal malignant melanoma (MM) of the oral cavity. MATERIALS AND METHODS: This was a multicenter study involving 8 Japanese universities. The medical records of 69 patients who were diagnosed with primary oral MM between January 2000 and December 2020 were retrospectively analyzed. Overall survival (OS) and prognostic factors for OS were analyzed statistically. RESULTS: There were 40 (58.0%) males and 29 (42.0%) females, and their mean (range) age was 69.8 ± 14.6 (22-96) years old. The most common primary site was the palate (30 patients, 43.5%). Stage IVA was the most common disease stage (36 patients, 52.2%). Radical therapy was performed in 55 patients (79.7%). The 2-year and 5-year OS rates of the 69 patients were 64.6% and 42.5%, respectively. The 2-year and 5-year OS rates of the stage III patients were 85.9% and 72.5%, respectively, and those of the stage IVA patients were 56.3% and 26.0%, respectively. The 1-year OS rate of the stage IVB/IVC patients was 26.7%. The 2-year and 5-year OS rates of the radical therapy group were 74.1% and 50.5%, respectively, whereas the 2-year OS rate of the non-radical therapy group was 26.0%. An advanced T classification was the only identified prognostic factor for OS (hazard ratio: 6.312, 95% confidence interval: 1.133-38.522, p < 0.05). CONCLUSIONS: Early detection and radical treatment are essential for improving the prognosis of oral MM patients. CLINICAL RELEVANCE: Early detection and adequate radical therapy leads to the better prognosis of oral MM patients.

Presence of periodontitis may synergistically contribute to cancer progression via Treg and IL-6.

A close causal relationship has been suggested to exist between cancer and periodontitis. We hypothesized that the immune surveillance system is impaired in patients with periodontitis, which contributes to cancer development and growth. Therefore, the present study investigated the relationship between immune surveillance mechanisms and periodontitis in cancer patients. The presence or absence of periodontitis was assessed and the peripheral blood (PB) concentrations of IL-6, immunosuppressive cytokines (VEGF, TGF-ß1, and CCL22) and proportion of T regulatory cells (Treg, CD3 + CD4 + CD25 + Foxp3 +) were measured. Subjects were classified into the following four groups: non-cancer patients without periodontitis (C - P -), non-cancer patients with periodontitis (C - P +), cancer patients without periodontitis (C + P -), and cancer patients with periodontitis (C + P +). The results of a multivariate analysis showed that the PB concentration of IL-6 was significantly higher in C + than in C- and higher in C + P + than in C + P -. The PB proportion of Treg was significantly higher in C + P + than in C + P -, C - P + , and C - P -. The results of this study suggested that the presence of periodontitis and cancer synergistically increased Treg in PB, which may be one of the underlying causes of immunosuppression and immune evasion in cancer. It was also suggested that the presence of periodontal disease and/or cancer also increases IL-6 in PB, which would be associated with cancer progression. These results suggest the possibility that the presence of periodontitis might synergistically contribute to cancer progression.

Detection of swallowing disorders with a multiple-channel surface electromyography sensor sheet.

Background/purpose: A sensor sheet comprising multiple electromyography electrodes that can be used to measure a series of multiple muscle activities related to swallowing was recently developed. In this study, we aimed to evaluate its utility in detecting swallowing disorders with a new method for the identification of muscle activity. Materials and methods: All participants were evaluated by using the repetitive saliva swallowing test and modified water swallowing test and were classified accordingly into participants with (n = 21; mean age, 81.6 [standard deviation, 10.1] years) and those without (n = 41; mean age, 70.0 [8.4] years) dysphagia. The sheet contains four pairs of electrodes, and surface electromyography (sEMG) was performed on the suprahyoid (position A: upper front of the suprahyoid muscles; position B: bottom rear of the suprahyoid muscles) and infrahyoid (position C: above the infrahyoid muscles; position D: beneath the infrahyoid muscles) muscles while the participants swallowed liquid, thickened water, paste, and jelly. The sEMG findings, including the duration of swallowing waveforms and the delay in swallowing onset from position A to positions B, C, and D, were compared between the groups. Results: The duration of muscle activity differed between the groups in the infrahyoid muscles when jelly (Mann-Whitney U test; position C, P = 0.007 and position D, P = 0.018) and thickened water (position C, P = 0.033) were swallowed. Conclusion: Our study demonstrates the utility of a novel sensor sheet developed for detecting swallowing disorders by using visual methods for identification of muscle activity.

Risk factors for osteoradionecrosis of the jaw in patients with oral or oropharyngeal cancer: Verification of the effect of tooth extraction before radiotherapy using propensity score matching analysis.

Background/purpose: Osteoradionecrosis of the jaw (ORN) often occurs in patients with head and neck cancer undergoing radiotherapy (RT). It has been recommended to extract the tooth before RT that may become source of infection, but in recent years, some investigators have reported that tooth extraction before RT increase the risk of developing ORN and therefore should be avoided. The purpose of the study is to evaluate the risk factors for ORN including tooth extraction before RT. Materials and methods: This was a retrospective study of 366 patients with oral or oropharyngeal cancer who underwent RT of 50 Gy or more at six university hospitals, with follow-up of at least six months post-RT. The relationship between each factor and ORN incidence was analyzed using the Cox proportional hazard model. Results: Periapical lesions, more than 50% loss of alveolar bone, and tooth extraction after RT significantly correlated with ORN. Intensity-modulated RT showed a lower incidence than three-dimensional conformal RT, although not statistically different. Tooth extraction before RT significantly reduced ORN incidence, after adjusting the background factors using propensity score matching. Conclusion: In patients with oral or oropharyngeal cancer who underwent RT, periapical lesions, more than 50% loss of alveolar bone, and tooth extraction after RT significantly increased the risk for ORN. Infected tooth extraction before RT significantly reduced the risk.

Perioperative oral care can prevent surgical site infection after colorectal cancer surgery: A multicenter, retrospective study of 1,926 cases analyzed by propensity score matching.

BACKGROUND: Surgical site infection is a common postoperative complication of colorectal cancer surgery, and surgical site infection increases medical costs, prolongs hospitalization, and worsens long-term prognosis. Perioperative oral care has been reported to be effective in preventing postoperative pneumonia, although there are only a few reports on its effectiveness in preventing surgical site infection. This study aimed to determine the role of perioperative oral care in surgical site infection prevention after colorectal cancer surgery. METHODS: In this study, 1,926 patients with colorectal cancer from 8 institutions were enrolled; 808 patients (oral care group) received perioperative oral care at the hospital's dental clinic, and 1,118 (control group) did not receive perioperative oral care. The data were matched by propensity score to reduce bias. Ultimately, a total of 1,480 patients were included in the analysis. RESULTS: The incidence of surgical site infection was significantly lower in the oral care group than in the control group (8.4% vs 15.7%, P < .001). Multivariate logistic regression analysis revealed 4 independent risk factors for surgical site infection: low albumin level, rectal cancer, blood loss, and lack of perioperative oral care. Lack of perioperative oral care had an odds ratio of 2.100 (95% confidence interval 1.510-2.930, P < .001). CONCLUSION: These results suggest that perioperative oral care can reduce the incidence of surgical site infection after colorectal cancer resection. Perioperative oral care may have an important role in the future perioperative management of colorectal cancer as a safe and effective method of surgical site infection prevention, although further validation in prospective studies is needed.