MRI radiomics may predict early tumor recurrence in patients with sinonasal squamous cell carcinoma.

OBJECTIVES: Sinonasal squamous cell carcinoma (SCC) follows a poor prognosis with high tendency for local recurrence. We aimed to evaluate whether MRI radiomics can predict early local failure in sinonasal SCC. METHODS: Sixty-eight consecutive patients with node-negative sinonasal SCC (January 2005-December 2020) were enrolled, allocated to the training (n = 47) and test sets (n = 21). Early local failure, which occurred within 12 months of completion of initial treatment, was the primary endpoint. For clinical features (age, location, treatment modality, and clinical T stage), binary logistic regression analysis was performed. For 186 extracted radiomic features, different feature selections and classifiers were combined to create two prediction models: (1) a pure radiomics model; and (2) a combined model with clinical features and radiomics. The areas under the receiver operating characteristic curves (AUCs) were calculated and compared using DeLong's method. RESULTS: Early local failure occurred in 38.3% (18/47) and 23.8% (5/21) in the training and test sets, respectively. We identified several radiomic features which were strongly associated with early local failure. In the test set, both the best-performing radiomics model and the combined model (clinical + radiomic features) yielded higher AUCs compared to the clinical model (AUC, 0.838 vs. 0.438, p = 0.020; 0.850 vs. 0.438, p = 0.016, respectively). The performances of the best-performing radiomics model and the combined model did not differ significantly (AUC, 0.838 vs. 0.850, p = 0.904). CONCLUSION: MRI radiomics integrated with a machine learning classifier may predict early local failure in patients with sinonasal SCC. CLINICAL RELEVANCE STATEMENT: MRI radiomics intergrated with machine learning classifiers may predict early local failure in sinonasal squamous cell carcinomas more accurately than the clinical model. KEY POINTS: • A subset of radiomic features which showed significant association with early local failure in patients with sinonasal squamous cell carcinomas was identified. • MRI radiomics integrated with machine learning classifiers can predict early local failure with high accuracy, which was validated in the test set (area under the curve = 0.838). • The combined clinical and radiomics model yielded superior performance for early local failure prediction compared to that of the radiomics (area under the curve 0.850 vs. 0.838 in the test set), without a statistically significant difference.

Surgical margin status and role of adjuvant therapy in human papillomavirus-positive oropharyngeal cancer.

BACKGROUND: We analyzed the difference in treatment results according to safety margin range and studied the role of adjuvant therapy in patients with human papillomavirus-positive (HPV+) oropharyngeal squamous cell carcinoma (OPSCC). MATERIALS AND METHODS: A total of 279 patients with HPV+ OPSCC were included in this study. RESULTS: Surgical margin and T classification were significant prognostic factors related to death. The difference in locoregional recurrence was analyzed by dividing the safety margin into groups of <1, 1-5, and >5 mm. There was no significant difference in local-regional recurrence for T1-T2 lesions between the three groups. Adjuvant therapy can significantly reduce disease recurrence in HPV+ OPSCC patients with risk factors. CONCLUSIONS: In T1-T2 lesions without other risk factors, even with a safety margin ≥1 mm, adjuvant therapy can potentially be omitted. Adjuvant therapy can significantly reduce disease recurrence in HPV+ OPSCC patients with risk factors.

Role of postoperative radiotherapy in resected adenoid cystic carcinoma of the head and neck.

PURPOSE: Although postoperative radiotherapy (PORT) is demonstrably effective in local control of head and neck adenoid cystic carcinoma (HNACC), its application is controversial and the subset of patients who would benefit most from PORT is unknown. Herein, we analyzed the data of HNACC patients to clarify the role of PORT. METHODS: We retrospectively reviewed 187 patients with nonmetastatic HNACC who underwent surgical resection between 2005 and 2019. The study endpoints were locoregional failure-free survival (LRFFS), progression-free survival (PFS), and overall survival (OS). Subgroup analysis and recursive partitioning analysis (RPA) were performed to identify patients most likely to benefit from PORT. RESULTS: With a median follow-up of 84.7 months, the 5-year LRFFS, PFS, and OS were 70.0%, 52.6%, and 86.4%, respectively. Survival was significantly shorter in patients who experienced local failure than in those who did not (5-year OS: 88.1% vs. 80.5%, P = 0.001). The local failure rate was significantly lower in patients who underwent PORT (16.9% vs. 31.0%, P = 0.021), despite the high frequency of adverse factors. Especially, significant decreases in local failure and similar OS rates could be obtained after PORT among patients with positive margins, T2-4 stage disease, and minor salivary gland tumors. The RPA model for PFS categorized patients into four groups according to three prognostic factors (T-stage, location, and sex). The RPA model for LRFFS and OS suggested three groups based on two factors (T-stage, margin for LRFFS; T-stage, grade 3 for OS). CONCLUSION: PORT could prevent dismal survival, while significantly reducing local failures in high-risk HNACC patients.

Treatment outcomes and radiotherapy deintensification strategies in human papillomavirus-associated tonsil cancer.

BACKGROUND: Human papillomavirus (HPV)-positive tonsil cancer has a better prognosis than HPV-negative tonsil cancer. Deintensification strategies to reduce or avoid radiotherapy (RT) for patients with HPV-associated tonsil cancer have been suggested. This study investigated the treatment outcomes of patients with HPV-associated tonsil cancer and suggested RT deintensification strategies. METHODS: A cohort of 374 patients with HPV-associated tonsil cancer treated with primary surgery or RT between 2008 and 2020 was retrospectively evaluated. Survival and locoregional control rates after primary surgery or RT were analyzed, and propensity score matching was performed to adjust for clinical factors. Pearson's chi-square or Fisher's exact test was used to compare categorical variables, and Student's t-test was used to compare continuous variables. The Kaplan-Meier method and log-rank test were used to assess overall survival, progression-free survival, and locoregional failure (LRF). RESULTS: No significant differences in survival or LRF were observed between the primary surgery and RT groups. Subgroup analysis was conducted for patients who underwent primary surgery. Advanced pathological N stage, negative contralateral nodes at diagnosis, abutting or positive surgical margins, and no adjuvant RT were independent risk factors for LRF. Advanced pathological T stage was an independent risk factor for LRF in patients who underwent primary surgery without subsequent adjuvant RT. None of the patients with pathological complete remission (CR) after induction chemotherapy died or experienced LRF. CONCLUSIONS: Our study revealed that the outcomes of primary surgery and primary RT in HPV-positive tonsil cancer were similar after adjusting for clinical factors. Primary RT might be considered instead of surgery in patients with advanced pathological T stage. In the case of pathological CR after induction chemotherapy, deintensification for adjuvant RT should be considered.

Robot-Assisted Total Thyroidectomy with or without Robot-Assisted Neck Dissection in Pediatric Patients with Differentiated Thyroid Cancer.

Pediatric thyroid cancer more frequently develops cervical node metastasis than adult thyroid cancer, even in differentiated thyroid carcinoma (DTC). Thus, cervical neck dissection often needs to be performed simultaneously with thyroidectomy in pediatric patients. Herein, we describe our experience with robot-assisted total thyroidectomy with/without robot-assisted neck dissection in pediatric patients compared with the conventional operated group. A total of 30 pediatric patients who underwent thyroidectomy for DTC between July 2011 and December 2019 were retrospectively reviewed. Among them, 22 underwent robot-assisted operation, whereas 8 underwent conventional operation. There was no statistical difference in the mean operation times, blood loss, drainage amounts, and hospital stay length between the robot-assisted and conventional operation groups; however, the operation time was less in the retroauricular approach subgroup (robot-assisted operation group) with better satisfaction on cosmesis. No postoperative complications, such as seromas, hemorrhages, or hematomas were observed. Our experience suggested that robot-assisted thyroidectomy with or without neck dissection through the retroauricular approach is a feasible and safe alternative treatment, producing outstanding esthetic results compared to the conventional approach, especially in pediatric patients with DTC.

Machine learning and magnetic resonance imaging radiomics for predicting human papilloma virus status and prognostic factors in oropharyngeal squamous cell carcinoma.

BACKGROUND: We attempted to predict pathological factors and treatment outcomes using machine learning and radiomic features extracted from preoperative magnetic resonance imaging (MRI) of oropharyngeal squamous cell carcinoma (OPSCC) patients. METHODS: The medical records and imaging data of 155 patients who were diagnosed with OPSCC were analyzed retrospectively. RESULTS: The logistic regression model showed that the area under the receiver operating characteristic curve (AUC) of the model was 0.792 in predicting human papilloma virus (HPV) status. The LightGBM model showed an AUC of 0.8333 in predicting HPV status. The performance of the logistic model in predicting lymphovascular invasion, extracapsular nodal spread, and metastatic lymph nodes showed AUC values of 0.7871, 0.6713, and 0.6638, respectively. In predicting disease recurrence, the LightGBM model showed an AUC of 0.8571. In predicting patient death, the logistic model showed an AUC of 0.8175. CONCLUSIONS: A machine learning model using MRI radiomics showed satisfactory performance in predicting pathologic factors and treatment outcomes of OPSCC patients.

Recent progress of robotic head and neck surgery using a flexible single port robotic system.

We performed robotic neck surgery through a transoral or retroauricular approach (RA) using the DaVinci SP and analyzed our experiences to evaluate the feasibility and safety of this system for performing RA neck surgeries. A total of 63 patients were enrolled in this study, consisting of 37 males and 26 females. All operations were successfully completed without significant complication in 63 patients with head and neck tumor. Using DaVinci SP, it is easy to insert three robotic arms into a long and narrow working space because all robotic arms and an endoscope are inserted through a single arm. Using the navigation function of the DaVinci SP, the endoscopic arm could be made into the shape of a "cobra" to secure proper visualization of the surgical site, which helps surgeons identify specific anatomic structures such as cranial nerve or vessels. We did not have any cases where robotic surgery was converted to open surgery due to severe bleeding or technical issues during surgery. The mean operative time was 207 min and the average hospital stay was 6.9 days. The time required for docking the surgical robot was within 10 min on average for DaVinci SP, which was much simpler and faster than that of the previous Si/Xi system. Based on our early experiences performing robotic head and neck surgery using the DaVinci SP, we confirmed that the system provided advanced technical advantages over the previous Si/Xi system in performing robotic surgery.

Postoperative Concurrent Chemoradiotherapy Versus Radiotherapy Alone for Advanced Oral Cavity Cancer in the Era of Modern Radiation Techniques.

BACKGROUND/PURPOSE: Surgery followed by postoperative radiotherapy (RT) has been considered the standard treatment for oral cavity squamous cell carcinoma (OCSCC) of advanced stages or with adverse prognostic factors. In this study, we compared the outcomes in patients with OCSCC who received postoperative concurrent chemoradiotherapy (CCRT) or postoperative RT alone using modern RT techniques. METHODS: A total of 275 patients with OCSCC treated between 2002 and 2018 were retrospectively analyzed. Adverse prognostic factor was defined as extranodal extension (ENE), microscopically involved surgical margin, involvement of ≥2 lymph nodes, perineural disease, and/or lymphovascular invasion (LVI). In total, 148 patients (54%) received CCRT and 127 patients (46%) received RT alone. More patients in the CCRT group had N3 disease and stage IVB disease (46.6% vs. 10.2%, p<0.001), ENE (56.1% vs. 15.7%, p<0.001), LVI (28.4% vs. 13.4%, p=0.033). RESULTS: With a median follow-up of 40 (range, 5-203) months, there were no significant differences in the 5-year overall survival (OS) and PFS between treatment groups. In the subgroup analysis according to high risk, the concurrent use of chemotherapy showed significantly improved OS in patients with ENE (HR 0.39, p=0.003). CONCLUSION: Our retrospective study showed that postoperative CCRT group had comparable survival outcomes to those in the RT alone group for advanced OCSCC in the era of modern RT techniques and indicated that concurrent chemotherapy should be administered to patients with ENE. Prospective randomized studies for confirmation are needed.

Effect of human acellular dermal matrix (Megaderm™) on infra-auricular depressed deformities, Frey's syndrome, and first bite syndrome following parotidectomy: a multi-center prospective study.

BACKGROUND: Parotidectomy is the primary treatment for parotid gland tumors. However, complications may include a prominent facial scar or infra-auricular depressed deformity, Frey's syndrome, first bite syndrome, or other facial pain, numbness, and paralysis. Acellular dermal matrix (ADM) has been widely used to prevent these complications in parotid surgery, but there have been no prospective, multi-center trials documenting its efficacy. This study evaluates the effectiveness of ADM implantation in preventing infra-auricular depressed deformity, Frey's syndrome and first bite syndrome after parotidectomy. METHODS: We analyzed 51 cases of standard parotidectomy and 58 cases of parotidectomy with implantation of Megaderm™ ADM through prospective multicenter trial. Acute complications including infection, seroma, hematoma, skin necrosis, and acute parotid area pain were evaluated 1 week postoperatively. Clinician grading of Frey's syndrome and blinded clinician evaluation of infra-auricular depressed deformities were conducted at 3, 6, and 12 months. Patients evaluated subjective satisfaction with neck appearance, Frey's syndrome quality, and acute parotid area pain at 3, 6, and 12 months. RESULTS: There was a higher incidence of seroma in the Megaderm™ group than in the control group at week 1. The incidence and total clinician-evaluated Frey's syndrome scores were significantly lower in the Megaderm™ group than in the control group at 3, 6, and 12 months. Both the objective and subjective evaluations of the facial contour showed a better outcome in the Megaderm™ group compared to the control group at 3, 6, and 12 months. There were no significant differences between the groups in the patient-reported Frey's syndrome quality scores at 3, 6, and 12 months, but the Megaderm™ group reported significantly less acute pain than the control group. CONCLUSIONS: ADM implantation can effectively reduce the occurrence of Frey's syndrome, infra-auricular depressed deformity, and first bite syndrome after parotidectomy. ADM may be especially advantageous in complex parotidectomy cases when significant complications are expected.

Overexpression of poliovirus receptor is associated with poor prognosis in head and neck squamous cell carcinoma patients.

PURPOSE: We aimed to investigate the prognostic value of multiple immune cell markers including programmed death-ligand 1 (PD-L1) and poliovirus receptor (PVR) in head and neck squamous cell carcinoma (HNSCC) using archival tumor tissues METHODS: Patients diagnosed with HNSCC who have undergone surgical resection in 2005-2012 were included. Correlations between PVR and PD-L1 expression and patient characteristics were analyzed by analysis of variance. The Kaplan-Meier method and log-rank test were used to estimate survival. P values < 0.05 were considered statistically significant. RESULTS: In total, 375 primary tumor tissues were analyzed using immunohistochemistry. High PVR expression was associated with a poor prognosis in terms of overall survival (OS) and recurrence-free survival (RFS), and tumors with high PVR expression were associated with a short OS. PD-L1 tumor expression did not have a prognostic impact on survival. Univariate analysis revealed that OS and RFS were affected by age and p16 and PVR expression; multivariate analysis revealed that age and p16 and PVR expression were the most important determinants of RFS. CONCLUSION: PVR overexpression is a poor prognostic factor in patients with HNSCC and co-targeting PVR and PD-L1 may be a promising therapeutic option that needs further investigation.

Comprehensive Analysis of Clinicopathologic Factors Predictive of an Unfavorable Prognosis in Patients With Acinic Cell Carcinoma of the Parotid Gland.

OBJECTIVES: In subset of patients, acinic cell carcinoma (AcCC) exhibits aggressive features such as recurrence, distant metastasis, and mortality. This study aimed to investigate clinicopathologic factors influencing patients' prognosis and to identify adverse features predictive of an unfavorable prognosis. METHODS: Between January 2000 and December 2016, 59 patients with AcCC were enrolled in this study. RESULTS: The patients' 5-year overall survival rate was 93.3%, and their 5-year recurrence-free survival rate was 80.5%. During the study period, recurrence occurred in 10 patients. The mean time to recurrence after surgery was 26 months (range, 5-60 months). During the study period, three patients died from the disease. Univariate analysis showed that sex, surgical extent, extranodal extension, T classification, and TNM stage were significantly associated with disease recurrence. Multivariate analysis showed that, among the clinicopathologic factors included in the analysis, only TNM stage displayed a statistically significant correlation with disease recurrence. CONCLUSION: Surgical treatment alone yielded good results for AcCC, and additional treatment did not affect the recurrence-free survival rate or the overall survival rate, even when the resection margin was less than 1 mm. Other pathologic factors did not show prognostic significance for disease recurrence or death.

Externally Monitored Versus Conventional Buried Flaps in Laryngopharyngeal Reconstruction.

OBJECTIVES: To compare the surgical outcomes of externally monitored and conventional buried flaps with the goal of determining the usefulness of external monitoring of buried flaps. METHODS: In this case-control study with propensity score matching, 30 patients were evenly divided into externally monitored buried flap and conventional buried flap groups. The total operative time for free flap reconstruction, the flap survival rate, the length of hospital stay, the initial time of a reliable visual assessment, complications, the final diet achieved, and the duration until diet initiation were compared between the groups. RESULTS: The mean operative time for reconstruction was 115 minutes (interquartile range, 85-150 minutes) and 142 minutes (interquartile range, 95-180 minutes) in the externally monitored and conventional groups, respectively (P= 0.245). The median length of hospital stay was 24 days (interquartile range, 18-30 days) and 27 days (interquartile range, 20-41 days) in the externally monitored and conventional groups, respectively (P=0.298). The median duration until diet initiation was 15 days (interquartile range, 15-21 days) and 18 days (interquartile range, 15-34 days) in the externally monitored and conventional groups, respectively (P=0.466). The final diet, initial time of a reliable visual assessment, and complications were comparable between the groups, but the external skin paddle provided an excellent visual assessment immediately postoperatively in all cases. CONCLUSION: The outcomes were comparable between the groups, indicating that externalization of the cutaneous component of a buried flap may be a straightforward and useful technique for monitoring a buried anterolateral thigh free flap in laryngopharyngeal reconstructions. The salvage and false-positive rates of compromised flaps should be compared in large subject groups in future studies to prove that the use of an external skin paddle improves flap monitoring.

Mouse-human co-clinical trials demonstrate superior anti-tumour effects of buparlisib (BKM120) and cetuximab combination in squamous cell carcinoma of head and neck.

BACKGROUND: Recurrent and/or metastatic squamous cell carcinoma of head and neck (R/M SCCHN) is a common cancer with high recurrence and mortality. Current treatments have low response rates (RRs). METHODS: Fifty-three patients with R/M SCCHN received continuous oral buparlisib. In parallel, patient-derived xenografts (PDXs) were established in mice to evaluate resistance mechanisms and efficacy of buparlisib/cetuximab combination. Baseline and on-treatment tumour genomes and transcriptomes were sequenced. Based on the integrated clinical and PDX data, 11 patients with progression under buparlisib monotherapy were treated with a combination of buparlisib and cetuximab. RESULTS: For buparlisib monotherapy, disease control rate (DCR) was 49%, RR was 3% and median progression-free survival (PFS) and overall survival (OS) were 63 and 143 days, respectively. For combination therapy, DCR was 91%, RR was 18% and median PFS and OS were 111 and 206 days, respectively. Four PDX models were originated from patients enrolled in the current clinical trial. While buparlisib alone did not inhibit tumour growth, combination therapy achieved tumour inhibition in three of seven PDXs. Genes associated with apoptosis and cell-cycle arrest were expressed at higher levels with combination treatment than with buparlisib or cetuximab alone. CONCLUSIONS: The buparlisib/cetuximab combination has significant promise as a treatment strategy for R/M SCCHN. CLINICAL TRIAL REGISTRATION: NCT01527877.

Non-invasive postoperative monitoring of pedicled rat skin flap using laser speckle contrast imaging.

PURPOSE: This study used non-invasive laser speckle contrast imaging (LSCI) modality to evaluate the blood flow changes in murine flap model and to investigate the clinical feasibility of the LSCI for postoperative monitoring. METHODS: Ten of 6-8 weeks old Spraque-Dawley rats with superficial inferior epigastric vessel based pedicled skin flaps were used in this experiment. The color changes of skin flap were evaluated by naked eyes and the LSCI modality 6, 24, and 48 h after surgery. RESULTS: In vessel ligated region of skin flap, skin color began to change to a bluish color immediately postoperatively. At 24 h postoperatively, skin necrosis was detectable with the naked eye and total necrosis occurred at 48 h postoperatively. Changes in laser speckle signal were consistent with changes observed with the naked eye, and blood flow index also presented significant differences between the ligated and non-ligated region. CONCLUSION: These correlated laser speckle signal patterns suggest that non-invasive monitoring of perfusion by LSCI is a useful technology that may be used to identify the ischemic skin flap.

Clinical-pathological prognostic factors and treatment failure patterns in T1-2 high-grade parotid gland cancer.

OBJECTIVES: The purpose of this study was to evaluate the treatment outcomes of patients with T1-2, high-grade parotid cancer, and to analyze the prognostic factors and treatment failure patterns. MATERIALS AND METHODS: Of the 101 patients who were diagnosed with high-grade parotid cancer from March 2003 to December 2018, a total of 39 males and 23 females who had T1-2 tumor were enrolled in this study. RESULTS: The average follow-up period of patients in this study was 63.9 months. The 5-year overall survival rate was 73.0%, and the 5-year disease-free survival rate was 57.6%. Thirty-nine patients underwent less-than-total parotidectomies, and the remaining 23 patients underwent total parotidectomies. After surgery, 50 patients received adjuvant treatment. During the study, 25 recurrences were documented, including nine local recurrences and 16 distant metastases. The average time period between the end of initial treatment and disease relapse was 17.0 months. A total of 16 patients succumbed to disease progression. Multivariate Cox proportional regression analysis showed that lymphovascular invasion (LVI) was an independent prognostic factor affecting disease recurrence and patient deaths. Among various factors, LVI and lymph node (LN) metastasis showed statistically significant correlations with distant metastasis. CONCLUSION: Although we achieved favorable therapeutic results using standard treatments in selected patients, T1-2 high-grade parotid cancers generally have poor prognosis. Distant metastases that occur during follow-up are a major factor in treatment failure and LVI and LN metastasis are significantly associated with distant metastasis.

Comparison of Surgical Outcomes of Robotic and Conventional Approaches in Patients with Pre- and Poststyloid Parapharyngeal Space Tumors.

BACKGROUND: Benefits and drawbacks of robotic surgical approaches for parapharyngeal space (PPS) tumors remain undetermined. The purpose of this study is to compare surgical outcomes of PPS tumor patients who underwent robotic surgery with those of patients who received conventional surgical treatment. PATIENTS AND METHODS: We retrospectively analyzed clinicopathologic data from 136 patients who underwent surgical removal of PPS tumors via conventional or robotic approaches. RESULTS: We identified PPS tumors in pre- and poststyloid regions in 87 (64%) and 49 (36%) patients, respectively. There were 48 (35.3%) pleomorphic adenomas, 36 (26.5%) schwannomas, and 24 (17.6%) paragangliomas. Conventional surgical techniques were performed in 83 patients, and robotic surgical approaches were administered to 53 patients. Transcervical-parotid and transcervical approaches were most commonly performed in conventional surgery, while transoral and retroauricular approaches were the preferred surgical methods in robotic surgery for pre- and poststyloid PPS tumors, respectively. Robotic surgery resulted in less estimated blood loss during poststyloid PPS tumor surgery. Postoperative cranial nerve complications were noted in 36 of 83 cases (43.4%) in the conventional surgery group and in 17 of 53 cases (32.1%) in the robotic surgery group. Intraoperative tumor spillage of pleomorphic adenoma showed no significant differences between the two groups (13.6% in conventional vs. 15.4% in robotic surgery). The mean follow-up time was 4.9 ± 3.4 years, and recurrences were observed in two patients during follow-up without a significant difference between the two groups (4.5% in conventional vs. 3.8% in robotic surgery). CONCLUSIONS: Robotic surgery in PPS tumors is feasible through transoral, retroauricular, or combined approaches and provides treatment outcomes comparable to those of conventional open surgery.

Correction: Molecular subtypes of oropharyngeal cancer show distinct immune microenvironment related with immune checkpoint blockade response.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Real impact of surgical robotic system for precision surgery of parotidectomy: retroauricular parotidectomy using da Vinci surgical system.

BACKGROUND: We performed robotic parotidectomy with or without robotic neck dissection via a retroauricular approach in patients with parotid benign and malignant tumors and analyzed treatment outcomes of the patients to evaluate the safety and feasibility of robotic parotidectomy. METHODS: Between January 2017 and July 2018, 53 patients received robotic parotidectomy with/without robotic neck dissection through a remote access retroauricular incision without a preauricular incision. RESULTS: All operations were successfully performed in all patients without significant perioperative complications or tumor spillage. Tumors were located in the superficial lobe of the parotid gland in 40 patients, and the remaining 13 tumors were located in the deep lobe of the parotid gland. Postoperative pathologic examination revealed benign tumor in 32 patients and malignant tumors in 18 patients. The mean operation time was 226 minutes in patients who underwent only parotidectomy and 375 minutes in patients who underwent parotidectomy with robotic neck dissection. The average amount of bleeding was 23 mL, and the amount of drainage after operation averaged 171 mL. The average length of hospital stay was 6 days. Postoperative complications were limited to transient facial paralysis in three patients, all of which resolved within 1 month. All patients were satisfied with their cosmetic results at 6 months after operation. CONCLUSIONS: Robotic parotidectomy with/without robotic neck dissection through a retroauricular approach was a feasible and safe technique in patients with parotid benign and malignant tumor. Specifically, we found it to be helpful in young patients with malignant parotid tumors who should receive cervical lymphadenectomy and parotidectomy, because it does not leave a visible scar on the face or neck. In the future, long-term follow-up will be necessary to validate its oncologic safety and functional outcomes.

Surgical extent and role of adjuvant radiotherapy of surgically resectable, low-grade parotid cancer.

BACKGROUND: Due to the rarity of low-grade parotid gland cancer and the diversity of histologic subtype, its optimal treatment modalities and prognostic factors have not been established yet. In this study, we aimed to identify the prognostic factors and adequate treatment modalities for patients with low-grade parotid gland cancer. METHODS: We retrospectively analyzed clinico-pathologic data from 287 patients with low-grade parotid gland cancer from 1999 to 2018. RESULTS: Recurrence-free survival, disease-specific survival, and overall survival rates at 10 years were 80.6%, 93.9%, and 84.4%, respectively. Among all patients, 56.1% received surgery alone, and the remaining 43.9% received surgery with adjuvant radiotherapy. Resection margin status and TNM stage were significant unfavorable prognostic factors. In patients with T1-2 tumor, surgical extent (total vs. less-than-total) did not show any significant effect on disease recurrence and patients' survival, and the disease was controlled well if a negative surgical margin was obtained after surgery, even with microscopic clear margin of<1 mm. In patients with adverse pathologic features (positive margin, lymphovascular invasion, perineural invasion, extracapsular nodal spread, T3-4, and N1-3), adjuvant radiotherapy significantly decreased loco-regional recurrence. CONCLUSIONS: Oncological outcomes were good in patients with low-grade parotid gland cancer with surgery and radiotherapy. In patients with T1-2 low-grade parotid gland cancer, surgery alone showed good local control rate regardless of the extent of surgery, if a negative surgical margin was obtained after surgery. Adjuvant radiotherapy played a significant role in controlling loco-regional recurrence in patients with adverse pathologic features.