The first wave of COVID-19 did not cause longer wait times in head and neck cancer. Experience of a French expert center.

BACKGROUND: Head and neck cancers (HNC) have poor survival prognosis, as tumors are often diagnosed at advanced stages in patients consulting late. The first lockdown linked to the 1st wave of COVID-19 (Coronavirus Disease 2019) disrupted consultation schedules in France. OBJECTIVE: The principal aim of the present study was to analyze consultation wait time in HNC during and after lockdown, in our university expert oncology reference center, to disclose any increase in treatment wait time. METHODS: A single-center retrospective study included patients with a first diagnosis of HNC. Three groups were distinguished: "lockdown", "post-lockdown", and a "control" group (corresponding to a reference period 1 year earlier). Intervals between first oncologic consultation and multidisciplinary tumor board (FC-MTB) and between MTB and first treatment (MTB-T) were assessed. RESULTS: One hundred and seven patients were included in the control group, 60 in the lockdown group and 74 in the post-lockdown group. There was no increase in median FC-MTB interval (respectively 35, 29 and 28 days) between the lockdown and post-lockdown groups compared to the control group (respectively P=0.2298 and P=0.0153). Likewise, there was no increase in MTB-T interval (27, 20 and 26 days respectively) (P=0.4203). CONCLUSION: No increase in wait times was observed during the lockdown and post-lockdown periods in our center.

Guidelines of the French Society of Otorhinolaryngology-Head and Neck Surgery (SFORL), part II: Management of recurrent pleomorphic adenoma of the parotid gland.

INTRODUCTION: The authors present the guidelines of the French Society of Otorhinolaryngology-Head and Neck Surgery (SFORL) for the management of recurrent pleomorphic adenoma (RPA) of the parotid gland. METHOD: A review of the literature was performed by a multidisciplinary task force. Guidelines were drafted, based on the articles retrieved and the work group members' individual experience. There were then read and re-edited by an independent reading group. The proposed recommendations were graded A, B or C on decreasing levels of evidence. RESULTS: Complete resection under neuromonitoring is recommended in case of RPA. The risks of progression and malignant transformation, which are higher the younger the patient, have to be taken into consideration. The risk of functional sequelae must be explained to the patient. MRI is recommended ahead of any surgery for parotid RPA, to determine extension and detect subclinical lesions. Radiotherapy should be considered in case of multi-recurrent pleomorphic adenoma after macroscopically complete revision surgery at high risk of new recurrence (microscopic residual disease), in case of RPA after incomplete resection, and in non-operable RPA.

Guidelines of the French Society of Otorhinolaryngology-Head and Neck Surgery (SFORL), part I: Primary treatment of pleomorphic adenoma.

INTRODUCTION: The authors present the guidelines of the French Society of Otorhinolaryngology-Head and Neck Surgery (SFORL) for the diagnosis and treatment of pleomorphic adenoma (PA) of the salivary glands. METHOD: A review of the literature was performed by a multidisciplinary task force. Guidelines were drafted based on the articles retrieved and the workgroup members' individual experience. Guidelines were graded A, B, C or expert opinion by decreasing level of evidence. RESULTS: In clinically suspected salivary gland PA, MRI should be performed, including head and neck lymph node levels. Fine needle aspiration cytology is particularly recommended for tumours difficult to characterise by MRI. Frozen section biopsy should be performed to confirm diagnosis and adapt the surgical procedure in case of intraoperative findings of malignancy. Complete resection of the parotid PA should be performed en bloc, including margins, when feasible according to tumour location, while respecting the facial nerve. Enucleation (resection only in contact with the tumour) is not recommended. For the accessory salivary and submandibular glands, complete en bloc resection should be performed.

Match between therapeutic proposal in multidisciplinary tumor board and actual treatment in head and neck cancer.

OBJECTIVES: There are few published studies evaluating the quality and outcome of multidisciplinary tumor board (MDTB) decisions. The aim of the present study was to evaluate adherence to MDTB recommendations in head and neck cancer and to document reasons in case of discordance. MATERIAL AND METHODS: We included all patients with newly diagnosed head and neck cancer presented in our MDTB meetings between January 1st and December 31st, 2018, whatever the tumor site, histology type and TNM classification. MDTB recommendations were compared to actual treatment. Discordance was defined as treatment partially or entirely different from the treatment decision recorded in the MDTB minutes. RESULTS: Board decisions were made for 344 new patients. Complete treatment concordance rate was 91.6% (315/344 patients), with deviation in 29 patients. Reasons for deviation were complications of treatment in 10 cases, patient refusal in 8, and physician's decision in 4 cases. Five patients died before therapy initiation. Mean interval from board discussion to treatment was 21 days, and depended on type of treatment (range, 1 to 74 days). CONCLUSION: This study shows the importance of evaluating concordance between the protocol proposed in the MDTB and the treatment actually received, to identify factors for deviation and remedy them when possible.

Radiological assessment of mandibular invasion in squamous cell carcinoma of the oral cavity and oropharynx.

BACKGROUND: Preoperative assessment of mandibular bone invasion in squamous cell carcinoma of the oral cavity and oropharynx is crucial for optimizing bone resection. The principal aim of this study was to evaluate the diagnostic value of CT and MR imaging for the diagnosis of mandibular bone invasion compared to the histological reference. In addition, we assessed the survival impact of bone invasion. PATIENTS AND METHODS: A single-center retrospective study included all consecutive patients treated by mandibular bone interruption for squamous cell carcinoma of the oral cavity and/or oropharynx. RESULTS: Sixty-eight patients were included. Prevalence of bone invasion on histology was 43%. Sensitivity, specificity and positive and negative predictive value were respectively 70%, 71%, 66% and 76% for CT compared with histologic analysis, 83%, 50%, 59% and 78% for MRI, and 83%, 62% 62%, 83% for associated CT and MRI. The two tests showed good agreement, with kappa index 0.69 (95% CI, 0.49-0.89) (P<0.0001). There was no difference in overall survival (log-rank>0.70) between the groups with and without bone invasion. CONCLUSION: CT and MRI are complementary for preoperative assessment of mandibular bone invasion, be it cortical and/or medullary, and in some cases may allow mandibular bone-sparing.

Presence in head and neck cancer multidisciplinary team meeting: The patient's experience and satisfaction.

BACKGROUND: In oncology, multi-disciplinary team meetings improve overall survival and reduce time to treatment in head and neck cancer. Interestingly, no study has examined the experience of patients attending an MTM. The present study addressed two questions: Does the MTM cause anxiety/depression for patients who are present? Are patients satisfied at the end of the meeting? PATIENTS AND METHODS: The study included all patients attending an MTM, who agreed to participate in the study and who fully completed two questionnaires. The Hospital Anxiety and Depression Scale (HADS) and a satisfaction questionnaire were filled out at three time-points: T0 before MTM, T1 at end of MTM, and T2 1 month after MTM for the HADS; and T1 and T2 for the satisfaction questionnaire. RESULTS: There were no significant differences in the number of patients experiencing anxiety between T0 and T1 (P=0.6085), T0 and T2 (P=1) or T1 and T2 (P=1). Likewise, there were no significant differences in the number of patients in depression between T0 and T1 (P=0.9397), T0 and T2 (P=1) or T1 and T2 (P=1). Mean satisfaction was good (question 14 on the satisfaction questionnaire: 8.7/10 at T1 and 7.7/10 at T2), but with a significant decrease between T1 and T2 (P=0.0009: i.e.,<0.05). Percentage information remembered (question 12) significantly decreased between T1 (mean 86%, standard deviation 0.2, median 94%) and T2 (78%±0.2, median 81%) (P=0.03). Presence in the MTM did not appear to induce or increase anxiety or pre-existing depressive syndrome.

Cost-effectiveness assessment in outpatient sinonasal surgery.

AIMS: To assess the cost-effectiveness of outpatient sinonasal surgery in terms of clinical efficacy and control of expenses. METHODS: A retrospective study was conducted from January 2014 to January 2016. Patients scheduled for outpatient sinonasal surgery were systematically included. Clinical data were extracted from surgical and anesthesiology computer files. The cost accounting methods applied in our institution were used to evaluate logistic and technical costs. The standardized hospital fees rating system based on hospital stay and severity in diagnosis-related groups (Groupes homogènes de séjours: GHS) was used to estimate institutional revenue. RESULTS: Over 2years, 927 outpatient surgical procedures were performed. The crossover rate to conventional hospital admission was 2.9%. In a day-1 telephone interview, 85% of patients were very satisfied with the procedure. All outpatient cases showed significantly lower costs than estimated for conventional management with overnight admission, while hospital revenue did not differ between the two. CONCLUSION: This study confirmed the efficacy of outpatient surgery in this indication. Lower costs could allow savings for the health system by readjusting the rating for the procedure. More precise assessment of cost-effectiveness will require more fine-grained studies based on micro costing at hospital level and assessment of impact on conventional surgical activity and post-discharge community care.

[Use of a Delphi survey to assess the hospital economic impact of innovative products: The example of idarucizumab a dabigatran-specific reversal agent]. / Utilisation du questionnaire Delphi pour anticiper l'impact économique des innovations thérapeutiques à l'hôpital : application à l'idarucizumab, le nouvel agent de réversion spécifique au dabigatran.

OBJECTIVES: The economic impact of therapeutic innovations on the hospital patient management cannot be easily estimated. The objective of this study is to illustrate the use of a Delphi survey as a support tool to identify the changes following the use of idarucizumab in dabigatran-treated patients with uncontrolled/life-threatening bleeding or who required emergency surgery/urgent procedures. METHODS: The Delphi questionnaires have been administrated to 8 emergency physicians or anesthetists from 6 different hospital centers. Following the answers, an economic valorization has been carried out on every parameter on which a consensus was reached (at least 4 answers showing an identical trend). A mean management cost for each etiology with and without the use of idarucizumab has thus been identified. RESULTS: For gastro-intestinal and other life-threatening bleedings (excepted intracranial bleedings), the total management cost of the hospital stay was respectively 6058 € (-35%) and 6219 € (-34%) following the use of the reversal agent. The hospital management cost for intracranial bleeding is slightly increasing to 9790 € (+3%). The cost of a stay for emergency surgery decreases to 6962€ (-2%). CONCLUSIONS: This study shows a positive economic impact following the use of the dabigatran-specific reversal agent for patients with uncontrolled/life-threatening bleeding excepted in the case of intracranial bleeding. Moreover, it points out that a Delphi survey is an easy way to predict the hospital economic impact of a therapeutic innovation when no other evaluation is possible.

Carboxylated nanodiamonds can be used as negative reference in in vitro nanogenotoxicity studies.

Nanodiamonds (NDs) are promising nanomaterials for biomedical applications. However, a few studies highlighted an in vitro genotoxic activity for detonation NDs, which was not evidenced in one of our previous work quantifying γ-H2Ax after 20 and 100 nm high-pressure high-temperature ND exposures of several cell lines. To confirm these results, in the present work, we investigated the genotoxicity of the same 20 and 100 nm NDs and added intermediate-sized NDs of 50 nm. Conventional in vitro genotoxicity tests were used, i.e., the in vitro micronucleus and comet assays that are recommended by the French National Agency for Medicines and Health Products Safety for the toxicological evaluation of nanomedicines. In vitro micronucleus and in vitro comet assays (standard and hOGG1-modified) were therefore performed in two human cell lines, the bronchial epithelial 16HBE14o- cells and the colon carcinoma T84 cells. Our results did not show any genotoxic activity, whatever the test, the cell line or the size of carboxylated NDs. Even though these in vitro results should be confirmed in vivo, they reinforce the potential interest of carboxylated NDs for biomedical applications or even as a negative reference nanoparticle in nanotoxicology. Copyright © 2017 John Wiley & Sons, Ltd.

Local extension staging of sinonasal tumours: retrospective comparison between CT/MRI assessment and pathological findings.

OBJECTIVES: To assess the reliability of clinical staging with CT and MRI in sinonasal cancers. METHODS: We conducted a retrospective review of patients who underwent surgery for a sinonasal cancer. The 7th edition of the TNM classification was used to establish tumour staging. Standardised preoperative CT/MRI staging was compared with the pathological staging based on specimens obtained during surgery from each subsite within and around the tumour. RESULTS: We analysed data from 68 patients between January 2010 and December 2014. A comparison of cT and pT stages was established for 49 naso-ethmoidal and 16 maxillary tumours. Clinical staging for naso-ethmoidal cT1 and maxillary cT2 was consistent with pathological results. Clinical staging for naso-ethmoidal cT2, cT3 and cT4b was overstated in comparison with pT findings. The positive predictive value of imaging was <65% for the lamina papyracea, the cribriform plate, the dura, and the frontal and sphenoid sinuses. Sensitivity was over 75% for each anatomical site except for the cribriform plate (73.3%) and the sphenoid sinus (57.2%). CONCLUSION: Systematic pathologic analysis of the anatomical areas around the sinonasal cancer has to be applied in further studies to improve our therapeutic management. CT/MRI mapping cannot replace accurate assessment of tumour extension during surgery.

Predictors of unanticipated admission within 30 days of outpatient sinonasal surgery.

OBJECTIVES: To identify predictive factors of readmission after day-case rhinologic surgery. METHODS: A 2-year retrospective chart review of patients scheduled for ambulatory sinonasal surgery in a tertiary medical center was conducted. The operating room and the anesthetic files were screened to identify demographic data, types of procedure, comorbidities and post-operative complications. RESULTS: From January 2014 to January 2016, 924 outpatient sinonasal procedures were identified. The overall readmission rate within the 30-postoperative days was 5.1% (2.9% for overnight hospital stay, 2.2% for unplanned post procedure visit to the hospital via the emergency room, or directly to the surgical unit within 30 days of discharge). Age at least 50 years, surgical duration at least 80 min, endoscopic sinus surgery procedures and postoperative nasal packing were identified as negative predictive factors of readmission. CONCLUSION: Careful scheduling of those higher-risk patients undergoing sinonasal surgery and appropriate postoperative observation should be implemented to improve healthcare quality in an outpatient setting.

Classification of parotidectomies: a proposal of the European Salivary Gland Society.

The objective of this study is to provide a comprehensive classification system for parotidectomy operations. Data sources include Medline publications, author's experience, and consensus round table at the Third European Salivary Gland Society (ESGS) Meeting. The Medline database was searched with the term "parotidectomy" and "definition". The various definitions of parotidectomy procedures and parotid gland subdivisions extracted. Previous classification systems re-examined and a new classification proposed by a consensus. The ESGS proposes to subdivide the parotid parenchyma in five levels: I (lateral superior), II (lateral inferior), III (deep inferior), IV (deep superior), V (accessory). A new classification is proposed where the type of resection is divided into formal parotidectomy with facial nerve dissection and extracapsular dissection. Parotidectomies are further classified according to the levels removed, as well as the extra-parotid structures ablated. A new classification of parotidectomy procedures is proposed.

French Society of ENT (SFORL) guidelines for care pathway organization in head and neck oncology (short version). Early management of head and neck cancer.

Early management in oncology is based on coordination and high-quality exchange between the various health-care partners. The present guidelines are based on a literature search with levels of evidence. Treatment waiting time can be optimized by performing assessment as early as possible (Expert opinion), to limit the interval (ideally, less than 4 weeks) between first consultation and data collection. In the first specialist consultation, diagnostic work-up should be scheduled and the data required for management should be determined (Grade B). Work-up may be conducted on a day-care basis or with conventional admission (Expert opinion). The patient's medico-social context should be taken into account from the outset, with social work involvement whenever necessary (Expert opinion). Pain and nutritional management should be planned for (Grade A) and realistic therapeutic education be provided (Expert opinion). Community-hospital teamwork for supportive care should be optimized (Expert opinion). Management should be early and multidisciplinary, to shorten delay between diagnosis and treatment initiation.

[Training of residents in obstetrics and gynecology: Assessment of an educational program including formal lectures and practical sessions using simulators]. / Formation des internes de gynécologie obstétrique : évaluation d'un programme pédagogique intégrant cours théoriques et sessions pratiques sur simulateurs.

OBJECTIVES: Evaluate an educational program in the training of residents in gynecology-obstetrics (GO) with a theory session and a practical session on simulators and analyze their learning curve. METHODS: Single-center prospective study, at the university hospital (CHU). Two-day sessions were leaded in April and July 2013. An evaluation on obstetric and gynecological surgery simulator was available to all residents. Theoretical knowledge principles of obstetrics were evaluated early in the session and after formal lectures was taught to them. At the end of the first session, a satisfaction questionnaire was distributed to all participants. RESULTS: Twenty residents agreed to participate to the training sessions. Evaluation of theoretical knowledge: at the end of the session, the residents obtained a significant improvement in their score on 20 testing knowledge. Obstetrical simulator: a statistically significant improvement in scores on assessments simulator vaginal delivery between the first and second session. Subjectively, a larger increase feeling was seen after breech delivery simulation than for the cephalic vaginal delivery. However, the confidence level of the resident after breech delivery simulation has not been improved at the end of the second session. Simulation in gynecological surgery: a trend towards improvement in the time realized on the peg-transfer between the two sessions was noted. In the virtual simulation, no statistically significant differences showed, no improvement for in salpingectomy's time. Subjectively, the residents felt an increase in the precision of their gesture. Satisfaction: All residents have tried the whole program. They considered the pursuit of these sessions on simulators was necessary and even mandatory. CONCLUSION: The approach chosen by this structured educational program allowed a progression for the residents, both objectively and subjectively. This simulation program type for the resident's training would use this tool in assessing their skills and develop learning curves.

Guidelines (short version) of the French Otorhinolaryngology - Head and Neck Surgery Society (SFORL) on patient pathway organization in ENT: The therapeutic decision-making process.

OBJECTIVES: The authors present the guidelines of the French Otorhinolaryngology - Head and Neck Surgery Society (SFORL) for patient pathway organization in head and neck cancer, and in particular for multidisciplinary team meetings. The present article concerns the therapeutic decision-making process. METHODS: A multidisciplinary work group was entrusted with a review of the scientific literature on the above topic. Guidelines were drawn up, based on the articles retrieved and the group members' individual experience. They were then read over by an editorial group independent of the work group. The final version was established in a coordination meeting. The guidelines were graded as A, B, C or expert opinion, by decreasing level of evidence. RESULTS: It is recommended that: an organ specialist should contribute to all multidisciplinary meetings on head and neck cancer; all members of the multidisciplinary meeting should have specific knowledge in head and neck cancer; any referring physician who does not follow the multidisciplinary meeting's advice should justify that decision; there should be sufficient time to prepare, discuss and sum up the cases dealt with in the multidisciplinary team meeting.

Histopathological classification of refractory chronic rhinosinusitis with nasal polyps.

OBJECTIVE: To delineate the histopathological characteristics of nasal mucosa in refractory chronic rhinosinusitis with nasal polyps (CRSwNP) in order to demonstrate subtypes of nasal polyps and their potential relation with lower airway comorbidity. STUDY DESIGN: Clinical- and pathological-based cross-sectional study Methods: Nasal polyp specimens were prospectively collected from patients with refractory CRSwNP referred to our institution for endoscopic sinus surgery. Oral and topical steroids were stopped 1 month before surgery. The pathological analysis was conducted by 2 independent reviewers with light microscopy on Hematoxylin-Eosin-Saffron stained slides. Each observer fulfilled a standardized protocol with cell count and stromal characterization on the most representative field. Mean grading scores were established. Morphological aspects were compared with the cell distribution and the clinical conditions. RESULTS: Among 36 patients, three subtypes of nasal polyps were depicted: eosinophilic edematous (64%), fibrous (9%) and intermediate with mixed edematous and collagen stromal structure (27%). Basement membrane thickening and seromucous gland hyperplasia were observed in the fibrosis sub-type (p<0.03). Eosinophilic mucosal infiltrate was significantly increased (p=0.026) in patients with concomitant pulmonary disease (n=21). Nasal polyp distribution was not influenced by asthma, allergy, previous surgery and smoking. CONCLUSION: Our 3-subtype classification of refractory CRSwNP in Caucasian population shows a predominant edematous structure whatever the clinical conditions may have been. Eosinophilia as a major factor of adaptive immune response in nasal inflammation is a feature of concomitant pulmonary disease. Further studies concerning mucosal remodelling and outcome assessment after sinus surgery are required to evaluate the impact of our classification on a daily basis.

Efficacy of tobramycin aerosol in nasal polyposis.

CONTEXT: Treatment of infected nasal polyposis. MATERIAL AND METHODS: Multicenter interventional prospective double-blind randomized study with matched groups: treatment with tobramycin aerosol versus isotonic saline aerosol. The study population included 55 patients: 23 receiving isotonic saline aerosol and 32 receiving tobramycin. A novel device (Easynose®) was used with an original principle limiting pulmonary deposition and ensuring homogeneous peripheral deposition in the nasal cavities. OBJECTIVES: The principal objective was to compare bacteriological eradication between tobramycin 150mg/3ml versus isotonic saline, both administered by nebulization via the Easynose® device. RESULTS AND CONCLUSION: Tobramycin aerosol administered via the Easynose® device showed significantly better bacteriological eradication than isotonic saline.

Olfactory cleft opacity and CT score are predictive factors of smell recovery after surgery in nasal polyposis.

OBJECTIVES: To assess subjective improvement of olfactory function following endoscopic sinus surgery (ESS) in chronic rhinosinusitis associated with nasal polyps (CRSwNP) and to analyse factors of recovery with the European Test of Olfactory Capabilities (ETOC). METHODS: We carried out a prospective study of 30 patients with CRSwNP from November 2011 to April 2013. The ETOC was filled the day before surgery and in the short term follow-up. Sixteen suprathreshold odorants with a detection task and a forced choice verbal identification task were tested. RESULTS: The mean composite score (MCS) improved at 3 and 6 months. The preoperative MCS was correlated to the Lund-Mackay score and to the olfactory cleft opacification on preoperative computed tomography (CT) scan. Multivariate linear regression modelling of patients with preoperative anosmia showed that the olfactory recovery at 3 months was predicted by the preoperative Lund-Mackay score and the age, and at 6 months by the preoperative Lund-Mackay score. CONCLUSION: With a convenient psychophysical test, we showed that olfactory cleft opacification and CT scan score could be predictive factors of olfaction disorder severity and improvement after ESS in CRSwNP. These results need to be strengthened in the long term with a larger panel of patients.

Epidemiology, prognosis and treatment of simultaneous squamous cell carcinomas of the oral cavity and hypopharynx.

OBJECTIVE: The study was designed to assess the prevalence, management and survival of patients with simultaneous squamous cell carcinomas of the oral cavity and hypopharynx (OC/HP). MATERIAL AND METHODS: A multicenter, retrospective study (2 university hospitals) was conducted between 2003 and 2007 on a series of 96 patients with simultaneous squamous cell cancers of the OC/HP. RESULTS: A total of 88 men and 8 women were included in the study: 81 patients presented double sites, 14 presented triple sites and one presented quadruple sites. The tumour sites most frequently observed were: hypopharynx in 61% of cases (involving the pyriform sinus in 42% of cases) and the oropharynx in 59% of cases (involving the palatine tonsil in 30% of cases). Upper aerodigestive tract endoscopy under general anaesthesia revealed a simultaneous lesion not suspected on clinical examination in 45% of patients: the site discovered on endoscopy was hypopharyngeal in 2 out of 3 cases; the tumour was classified T1 or T2 in 95.5% of cases. Patients treated simultaneously for all sites had a better prognosis than patients in whom each tumour was treated separately. The 5-year specific survival was 34% and the 5-year overall survival was 28%. CONCLUSION: The prevalence of simultaneous squamous cell carcinomas of the oral cavity and hypopharynx ranges between 1 to 7.4% in the literature and was 4.6% in the present series. A common treatment strategy for each of the patient's tumours appears to be superior to the current theoretical approach that consists of considering each tumour separately.

Open partial horizontal laryngectomies: a proposal for classification by the working committee on nomenclature of the European Laryngological Society.

We present herein the proposal of the European Laryngological Society working committee on nomenclature for a systematic classification of open partial horizontal laryngectomies (OPHL). This is based on the cranio-caudal extent of laryngeal structures resected, instead of a number of different and heterogeneous variables present in existing nomenclatures, usually referring to eponyms, types of pexy, or inferior limit of resection. According to the proposed classification system, we have defined three types of OPHLs: Type I (formerly defined horizontal supraglottic laryngectomy), Type II (previously called supracricoid laryngectomy), and Type III (also named supratracheal laryngectomy). Use of suffixes "a" and "b" in Type II and III OPHLs reflects sparing or not of the suprahyoid epiglottis. Various extensions to one arytenoid, base of tongue, piriform sinus, and crico-arytenoid unit are indicated by abbreviations (ARY, BOT, PIR, and CAU, respectively). Our proposal is not intended to give a comprehensive algorithm of application of different OPHLs to specific clinical situations, but to serve as the basis for obtaining a common language among the head and neck surgical community. We therefore intend to present this classification system as a simple and intuitive teaching instrument, and a tool to be able to compare surgical series with each other and with non-surgical data.