Background:The radiosensitizing effect of epidermal growth factor inhibitors (EGFRIs), such as cetuximab, in patients with p16-positive HPV-associated oropharyngeal squamous cell carcinoma (HPV + OPSCC) is not clear. There is no randomized trial investigating the addition of EGFRI to radiotherapy (RT) alone specifically in HPV + OPSCC, and available evidence in subgroup analyses have mostly suggested discouraging results. The current analysis provides additional data by combining results from two randomized trials. Materials and Methods:Patients from two randomized ARTSCAN trials were included. The RT alone-group consisted of patients treated with conventionally fractionated RT (68.0 Gy in 34 fractions over 6.5 weeks) in the first ARTSCAN trial. The cetuximab group comprised patients treated with conventionally fractionated RT (same RT-schedule) and receiving concurrent cetuximab in the ARTSCAN III trial. Only patients with HPV + OPSCC were included. Comparisons between groups were made by univariable and adjusted Cox regression models, and illustrated with the Kaplan-Meier method. Results:74 and 89 patients were eligible in the first ARTSCAN trial (RT alone) and ARTSCAN III (RT + cetuximab), respectively, with a median follow-up of 5.3 (interquartile range 5.0-5.5) years. Baseline characteristics were generally well-balanced. The five-year loco-regional control for RT alone was 84% (95%CI 76-93) and for RT + cetuximab 82% (95%CI 75-91), with an adjusted hazard ratio of 1.18 (95%CI 0.54-2.6, p = 0.70). Interpretation:The study does not support a radiosensitizing role when adding EGFRI cetuximab to RT in patients with HPV + OPSCC.

BACKGROUND:Radiotherapy (RT) has been the treatment of choice for T1 glottic squamous cell carcinomas with curative intent; however, transoral microsurgery (MLS) has gradually taken its place. The objective of this study was to compare the outcomes of the two treatment modalities. METHODS:The Swedish Head and Neck Cancer Register contains records for 783 patients who had T1 glottic squamous cell carcinomas and planned to undergo either RT or MLS with curative intent from 2008 until 2019. These included 652 patients with T1a tumors and 125 patients with T1b tumors, resulting in 777 eligible patients. RESULTS:Surgical treatment led to an increased risk of recurrence compared with RT for patients who had both T1a and T1b tumors (p < .001). Forty-seven patients (6.0%) underwent laryngectomy after primary treatment. Patients with T1b tumors had a higher risk of undergoing laryngectomy (p = .01), but no significant difference in the frequency of laryngectomy was noted between the treatment modalities. Patients who had T1b tumors had a significantly worse 5-year overall survival rate compared with those who had T1a tumors, but treatment modality did not influence the overall survival rate. CONCLUSIONS:In this population-based study of 777 patients with T1 glottic squamous cell carcinomas, no significant difference in overall survival was observed at 5 years based on treatment modality (MLS or RT). Overall survival was worse for patients with T1b carcinomas, and these patients were at an elevated risk of requiring laryngectomy. An increased risk of recurrence within 3 years was observed after surgical treatment for both T1a and T1b tumors.

PURPOSE:The study investigated curative radiation therapy (RT) plus cisplatin versus RT plus cetuximab in patients with locoregionally advanced head and neck squamous cell carcinoma (HNSCC). METHODS AND MATERIALS:This was a Swedish multicenter randomized phase 3 study. Included patients were randomized 1:1. Patients with T3-T4 tumors underwent a second randomization 1:1 between a final RT dose of 68.0 and 73.1 Gy to the primary tumor. Cisplatin dosage was 40 mg/m2/wk during RT. Cetuximab was administered with a loading dose of 400 mg/m2 1 week before start of RT, followed by weekly doses of 250 mg/m2 during RT. Primary endpoint was overall survival (OS), evaluated by adjusted Cox regression analysis. Secondary endpoints were locoregional control, pattern of failure, morbidity, quality of life (QL), and comparisons between dose-escalated RT and standard-dose RT in T3-T4 tumors. RESULTS:Following an unplanned interim analysis, patient inclusion was prematurely closed. The intention-to-treat population included 291 patients, 76% of whom had p16-positive oropharyngeal cancer. Median follow-up was 7.5 years for OS and 5.3 years for treatment efficacy. Five-year OS was 82% (95% confidence interval [CI], 76-89) in the RT plus cisplatin group compared with 71% (95% CI, 64-79) in the RT plus cetuximab group (log-rank P = .019). Adjusted hazard ratios for OS, locoregional failure, and distant failure were 1.66 (95% CI, 1.08-2.56; P = .021), 2.24 (95% CI, 1.25-4.02; P = .007), and 1.44 (95% CI, 0.67-3.09; P = .34), respectively, for patients treated with concomitant cetuximab versus cisplatin. Although potentially affected by the early termination of patient inclusion, no improvement in local control was found in patients with T3-T4 tumors receiving RT dose escalation (adjusted HR, 0.63; 95% CI, 0.30-1.34; P = .23). Late morbidity and QL were similar between the treatment groups. CONCLUSIONS:The study showed inferior treatment outcomes for cetuximab compared with cisplatin concurrent with RT. Cisplatin remains standard concomitant treatment for locoregionally advanced HNSCC.

BACKGROUND/AIM:Radioactive iodine (RAI) treatment is a cornerstone of treatment of differentiated thyroid carcinoma. Although serious RAI-related complications are uncommon, there have been reports of airway emergencies. Here, a life-threatening airway complication after RAI treatment is reported and previously reported cases are reviewed.CASE REPORT:A 79-year old man with Hürthle cell carcinoma and a remnant thyroid lobe after surgery developed an edema compromising the airway two days after receiving radioactive iodine treatment. An emergency awake intubation and tracheostomy were performed. He could be successfully de-cannulated 17 days later with no long-term complications.CONCLUSION:Although rare, life-threatening airway complications after radioactive iodine treatment, especially with high dose treatment in patients with remaining thyroid tissue, can occur and these patients should be supervised where these complications can be managed.

Background The base of tongue squamous cell carcinoma (BOTSCC) is mainly an HPV-related tumor. Radiotherapy (EBRT) +/- concomitant chemotherapy (CT) is the backbone of the curatively intended treatment, with brachytherapy (BT) boost as an option. With four different treatment strategies in Sweden, a retrospective study based on the population-based Swedish Head and Neck Cancer Register (SweHNCR) was initiated. Material and methods Data on tumors, treatment and outcomes in patients with BOTSCC treated between 2008 and 2014 were validated through medical records and updated as needed. Data on p16 status were updated or completed with immunohistochemical analysis of archived tumor material. Tumors were reclassified according to the UICC 8th edition. Results Treatment was EBRT, EBRT + CT, EBRT + BT or EBRT + CT + BT in 151, 145, 82 and 167 patients respectively (n = 545). A p16 analysis was available in 414 cases; 338 were p16+ and 76 p16-. 5-year overall survival (OS) was 68% (95% CI: 64-72%), with76% and 37% for p16+ patients and p16- patients, respectively. An increase in OS was found with the addition of CT to EBRT for patients with p16+ tumors, stages II-III, but for patients with tumor stage I, p16+ (UICC 8) none of the treatment strategies was superior to EBRT alone. Conclusion In the present retrospective population-based study of BOTSCC brachytherapy was found to be of no beneficial value in curatively intended treatment. An increase in survival was found for EBRT + CT compared to EBRT alone in patients with advanced cases, stages II and III (UICC 8), but none of the regimes was significantly superior to EBRT as a single treatment modality for stage I (UICC 8), provided there was p16 positivity in the tumor. In the small group of patients with p16- tumors, a poorer prognosis was found, but the small sample size did not allow any comparisons between different treatment strategies.

Background and purpose: An earlier prospective randomised multicentre study (ARTSCAN) in head and neck cancer patients that compared conventionally fractionated radiotherapy (CF) with accelerated radiotherapy (AF) was inconclusive. In the subgroup of oral cavity squamous cell cancer (OCSCC) a large absolute, but not statistically significant, difference in local control was seen in favour of AF. This difference was more pronounced in resectable tumours. The finding raised the hypothesis that AF could be beneficial for OCSCC patients. In addition, the longstanding controversy on pre- or postoperative radiotherapy was addressed. Materials and methods: Patients with OCSCC, judged to withstand and likely benefit from combined therapy, were recruited. Subjects were randomised to either preoperative AF with 43 fractions given as a concomitant boost with two fractions/day to the tumour bearing volume to a total dose of 68 Gy in 4.5 weeks followed by surgery, or primary surgery with postoperative CF, total dose 60 or 66 Gy in 6-7 weeks. For patients whose tumours had high-risk features, 66 Gy and concomitant cisplatin was prescribed. Results: 250 patients were randomised. Median follow-up was 5 years for locoregional control (LRC) and 9 years for overall survival (OS). There were no statistically significant differences between the two treatment arms regarding LRC and OS. LRC at five years was 73% (95% CI, 65-82) in preoperative AF and 78% (95% CI, 70-85) in postoperative CF. Toxicity was more pronounced in preoperative AF. Conclusion: This study does not support that AF prior to surgery improves outcome in oral cavity cancer compared with postoperative CF. (C) 2021 The Authors. Published by Elsevier B.V.

BACKGROUND/AIM:Post-treatment surveillance of patients with squamous cell oropharyngeal carcinoma (SCOPC) consists of routine follow-up visits for 5 years. It has been suggested that this program is inefficient for finding recurrences and increasing survival. The primary study objective was to investigate how recurrences after treatment for SCOPC were detected, i.e., at routine follow-up visits, at patient-initiated visits, or incidentally. The secondary objective was to investigate whether 2-year survival after diagnosis of recurrence depended on the manner of detection.PATIENTS AND METHODS:Patients with recurrences from SCOPC between 1988 and 2018 were included. Survival was analysed by the Kaplan-Meier method with log-rank test.RESULTS:A total of 75 patients were included. Almost one-third were alive 2 years after the diagnosis of recurrence. Recurrences were detected at routine follow-up visits in 50.7%, at patient-initiated visits in 42.7% and 6.6% were found incidentally. There was an increased survival in the patient-initiated group, but this was not significant.CONCLUSION:The majority of recurrences in both groups compared were amenable to curative treatment.

Background/Aim: Follow-up after treatment for oral tongue cancer consists of routine follow-up visits for five years. It has been suggested that this program is inefficient for finding recurrences. The primary objective of this study was to investigate how recurrences are detected; at routine follow-up visits, at patient-initiated visits, or incidentally. The secondary objective was to investigate whether the two-year survival after diagnosis of recurrence depended on the manner of detection. Patients and Methods: Patients with recurrences from oral tongue cancer between 1988 and 2016 were included. Survival was analysed by the Kaplan-Meier method and log-rank test. Results: A total of 75 patients were included. In 67% of patients, recurrences were detected at routine follow-up visits, and in 27% at patient-initiated visits. No significant difference in survival between the groups was found (p=0.56). Conclusion: The majority of recurrences were detected at routine follow-up visits. Patient-initiated recurrence detection did not lead to increased survival.

Background/Aim: Electrochemotherapy (ECT) is a cancer treatment modality where the efficacy of a chemotherapeutic agent is enhanced by an electrical field. It is an established palliative treatment for cutaneous metastases but its role in curative treatment remains mostly undetermined. Studies have previously reported that ECT can be a safe curative treatment in both skin cancer and oral cavity cancer. The primary aim of this case study was to report the long-term results of ECT in curative treatment of four patients with skin or oral cavity cancer. The study also compares two different ECT treatment protocols. Patients and Methods: Three patients with oral cavity cancer and one patient with skin cancer were included. One patient had a primary oral tongue cancer and the others had persistent/recurrent tumors after previous treatment. They were treated with ECT either as a primary, adjuvant or salvage treatment with curative intent. The median follow-up period was 60 months. Results: There was one case of local recurrence after treatment in the follow-up period. In the other three patients, no recurrence was recorded. There was one serious adverse airway event. There was a significant difference in the bleomycin dose between the two studied protocols, especially for large tumors. Conclusion: ECT can be a safe mono-modality and adjuvant curative treatment in advanced skin cancer and primary and recurrent oral cavity cancer.

Background/Aim: Previous studies of node negative oral squamous cell carcinoma have shown a benefit of elective neck dissection compared to observation. Evidence for radiotherapy as single-modality elective treatment of the node-negative neck is so far lacking. Patients and Methods: In a retrospective material of 420 early-stage oral cancers from 2000 to 2016, overall survival, disease-free survival, and regional relapse-free survival were calculated with the Kaplan-Meier method. Results: At five years, overall survival was 59.7%, disease-specific survival was 77.2%, and regional relapse-free survival was 83.5%. Among those with adjuvant treatment of the neck after surgery of T1-T2 tumours during 2009-2016, regional relapse-free survival at five years was 85.7% for elective radiotherapy of the neck and 87.4% for elective neck dissection. Conclusion: Elective radiotherapy to the neck with a modern technique and adequate dose might be an alternative to neck dissection for patients with early-stage oral squamous cell cancer.

Background This exploratory, registry-based, cross-sectional study aimed to evaluate patients' health-related quality of life (HRQOL) in a subsite of oropharyngeal cancer: cancer of the base of the tongue (CBT). Methods CBT patients, treated with curative intent, completed the EORTC QLQ-C30 and QLQ-H&N35 questionnaires 15 months after diagnosis. The HRQOL of CBT patients was compared to reference scores from the general population and to that of tonsillar carcinoma patients. Results The 190 CBT patients scored significantly worse than members of the general population on most scales. CBT patients with human papilloma virus (HPV)-positive tumors had significantly better HRQOL on 8 of 28 scales than HPV-negative patients. Compared to 405 tonsillar carcinoma patients, CBT patients had significantly worse HRQOL on 8 of the 28 scales, the majority local head and neck related problems. Conclusion One year after treatment, CBT patients' HRQOL was significantly worse in many areas compared to that of the general population and slightly worse than that of tonsillar carcinoma patients.

BACKGROUND:The health-related quality of life (HRQOL) of tonsillar carcinoma survivors was explored to investigate any HRQOL differences associated with tumor stage and treatment. The survivors' HRQOL was also compared to reference scores from the population.METHODS:In this exploratory cross-sectional study patients were invited 15 months after their diagnosis and asked to answer two quality of life questionnaires (EORTC QLQ- C30, EORTC QLQ- HN35), 405 participated.RESULTS:HRQOL was associated with gender, with males scoring better than females on a few scales. Patients' HRQOL was more associated with treatment than tumor stage. Patients' HRQOL was worse than that in an age- and sex-matched reference group from the normal population, the largest differences were found for problems with dry mouth followed by problems with sticky saliva, senses, swallowing and appetite loss.CONCLUSIONS:The tonsillar carcinoma patients had a worse HRQOL compared to the general population one year after treatment.

PURPOSE:We performed an open-label randomized controlled phase III study comparing treatment outcome and toxicity between radiotherapy (RT) with concomitant cisplatin versus concomitant cetuximab in patients with locoregionally advanced head and neck squamous cell carcinoma (HNSCC; stage III-IV according to the Union for International Cancer Control TNM classification, 7th edition).MATERIALS AND METHODS:Eligible patients were randomly assigned 1:1 to receive either intravenous cetuximab 400 mg/m2 1 week before start of RT followed by 250 mg/m2/wk, or weekly intravenous cisplatin 40 mg/m2, during RT. RT was conventionally fractionated. Patients with T3-T4 tumors underwent a second random assignment 1:1 between standard RT dose 68.0 Gy to the primary tumor or dose escalation to 73.1 Gy. Primary end point was overall survival (OS) evaluated using adjusted Cox regression analysis. Secondary end points were locoregional control, local control with dose-escalated RT, pattern of failure, and adverse effects.RESULTS:Study inclusion was prematurely closed after an unplanned interim analysis when 298 patients had been randomly assigned. At 3 years, OS was 88% (95% CI, 83% to 94%) and 78% (95% CI, 71% to 85%) in the cisplatin and cetuximab groups, respectively (adjusted hazard ratio, 1.63; 95% CI, 0.93 to 2.86; P = .086). The cumulative incidence of locoregional failures at 3 years was 23% (95% CI, 16% to 31%) compared with 9% (95% CI, 4% to 14%) in the cetuximab versus the cisplatin group (Gray's test P = .0036). The cumulative incidence of distant failures did not differ between the treatment groups. Dose escalation in T3-T4 tumors did not increase local control.CONCLUSION:Cetuximab is inferior to cisplatin regarding locoregional control for concomitant treatment with RT in patients with locoregionally advanced HNSCC. Additional studies are needed to identify possible subgroups that still may benefit from concomitant cetuximab treatment.

A fundamental problem in radiotherapy is the variation of organ at risk (OAR) volumes. Here we present our initial experience in engaging a large Radiation Oncology (RO) community to agree on national guidelines for OAR delineations. Our project builds on associated standardization initiatives and invites professionals from all radiotherapy departments nationwide. Presently, one guideline (rectum) has successfully been agreed on by a majority vote. Reaching out to all relevant parties in a timely manner and motivating funding agencies to support the work represented early challenges. Population-based data and a scalable methodological approach are major strengths of the proposed strategy.

BACKGROUND:Electrochemotherapy (ECT) is a cancer treatment modality where the intracellular accumulation of chemotherapeutic agents is enhanced by an applied electrical field.AIMS/OBJECTIVES:To evaluate the long-term efficacy, safety and functional outcome after ECT treatment in high-risk non-melanoma skin cancer (NMSC) with curative intent.MATERIALS AND METHODS:Seven patients with SCC or BCC in the head and neck area were treated with ECT with intratumoral bleomycin administration.RESULTS:Five patients were cured by ECT as a mono-modality treatment after a median 10-year follow-up period. Two patients had recurrences and/or persisting tumors after treatment that required salvage surgery and radiotherapy. In two patients, the eye was spared with no visual impairment. In another patient, full facial nerve function was spared.CONCLUSIONS:ECT can be a curative as well as an organ and function-sparing mono modality treatment in high-risk NMSC.SIGNIFICANCE:Today ECT is mostly used as a palliative treatment. Its curative potential should be further investigated. Randomized studies comparing ECT with standard treatment is needed. Hopefully, this small study can encourage such studies.

Background: This was a validation study of a regional register of oral cancer in Örebro, Sweden. The purpose was to assess the rate of errors in baseline, and treatment, and the completeness and accuracy of data on recurrences. Materials and Methods: A total of 653 cases with squamous cell cancer in the oral cavity were identified from the register. A randomized sample of 73 (11%) was selected, and a set of relevant data was compared to medical records. Results: Data on patient and tumour characteristics showed high accuracy, with 98% correct data and more than 99% of treatment data were correct. Follow-up data had a higher rate of errors, with 23% of recurrences not recorded, 13.6% misclassified, and 9.1% of cases showing errors in timing of the recurrence. Conclusion: data concerning patients, tumour status, and treatment in the Regional Head and Neck Register in Örebro are highly accurate. However, the follow-up data contain a higher rate of errors, that must be taken into consideration when evaluating outcome after treatment.

A. M€akitie , M. Ruuskanen , J. Bentzen, E. Brun, M. Gebre-Medhin, S. Friesland, E. Marsk, L. Hammarstedt-Nordenvall, E. Gille, J. Reizenstein, G. Adell, L. Farnebo , J. Rzepecki, H. Haugen, K. S€ oderstr€ om, B. Zackrisson, S. Bergstr€ om, B. L€ od en, L. Cederblad, G. Laurell , E. Smeland, J. Folkvard Evensen, J. Å. Lund, H. Tøndel, Å. Karlsdottir, J. J ohannsson, J. Johansen, C. A. Kristensen, K. Jensen, L. J. Andersen, P. Koivunen, M. Korpela, L. Voutilainen, T. Wigren, H. Minn, H. Joensuu, J. Overgaard and K. Saarilahti Department of Otorhinolaryngology – Head and Neck Surgery, University of Helsinki and Helsinki University Hospital, Helsinki, Finland; Division of Ear, Nose and Throat Diseases, Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden; Department of Otorhinolaryngology – Head and Neck Surgery, Turku University Hospital, Turku, Finland; Department of Oncology, Herlev University Hospital, Copenhagen, Denmark; Department of Oncology, Skane University Hospital, Lund University, Sweden; Department of Oncology, Karolinska University Hospital, Stockholm, Sweden; Department of Oncology, € Orebro University Hospital, € Orebro, Sweden; Department of Oncology, Link€oping University Hospital, Link€oping, Sweden; Department of Otorhinolaryngology – Head and Neck Surgery, Link€oping University Hospital, Link€oping, Sweden; Department of Oncology, Sahlgrenska University Hospital, Gothenburg, Sweden; Department of Radiation Sciences, Umeå University, Umeå, Sweden; Department of Oncology, G€avle Hospital, G€avle, Sweden; Department of Oncology, Karlstad Hospital, Karlstad, Sweden; Department of Oncology, Uppsala University Hospital, Uppsala, Sweden; Department of Otorhinolaryngology – Head and Neck Surgery, Uppsala University Hospital, Uppsala, Sweden; Department of Oncology, University Hospital North Norway, Tromsoe, Norway; Department of Oncology, Oslo University Hospital, Oslo, Norway; Department of Oncology, Trondheim University Hospital, Trondheim, Norway; Department of Oncology, Haukeland University Hospital, Bergen, Norway; Department of Oncology, Landspitali University Hospital, Reykjavik, Iceland; Department of Oncology, Odense University Hospital, Odense, Denmark; Department of Oncology, The Finsen Centre, Rigshospitalet, Copenhagen, Denmark; Department of Oncology, Aarhus University Hospital, Aarhus, Denmark; Department of Oncology, Aalborg Hospital, Aalborg, Denmark; Department of Otorhinolaryngology – Head and Neck Surgery, Oulu University Hospital, Oulu, Finland; Department of Oncology, Oulu University Hospital, Oulu, Finland; Department of Oncology, Kuopio University Hospital, Kuopio, Finland; Department of Oncology, Tampere University Hospital, Tampere, Finland; Department of Oncology, Turku University Hospital, Turku, Finland; Department of Oncology, Helsinki University Hospital and University of Helsinki, Helsinki, Finland; Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark

PURPOSE:To evaluate two commercial CT metal artifact reduction (MAR) algorithms for use in proton treatment planning in the head and neck (H&N) area.METHODS:An anthropomorphic head phantom with removable metallic implants (dental fillings or neck implant) was CT-scanned to evaluate the O-MAR (Philips) and the iMAR (Siemens) algorithms. Reference images were acquired without any metallic implants in place. Water equivalent thickness (WET) was calculated for different path directions and compared between image sets. Images were also evaluated for use in proton treatment planning for parotid, tonsil, tongue base, and neck node targets. The beams were arranged so as to not traverse any metal prior to the target, enabling evaluation of the impact on dose calculation accuracy from artifacts surrounding the metal volume. Plans were compared based on γ analysis (1 mm distance-to-agreement/1% difference in local dose) and dose volume histogram metrics for targets and organs at risk (OARs). Visual grading evaluation of 30 dental implant patient MAR images was performed by three radiation oncologists.RESULTS:In the dental fillings images, ΔWET along a low-density streak was reduced from -17.0 to -4.3 mm with O-MAR and from -16.1 mm to -2.3 mm with iMAR, while for other directions the deviations were increased or approximately unchanged when the MAR algorithms were used. For the neck implant images, ΔWET was generally reduced with MAR but residual deviations remained (of up to -2.3 mm with O-MAR and of up to -1.5 mm with iMAR). The γ analysis comparing proton dose distributions for uncorrected/MAR plans and corresponding reference plans showed passing rates >98% of the voxels for all phantom plans. However, substantial dose differences were seen in areas of most severe artifacts (γ passing rates of down to 89% for some cases). MAR reduced the deviations in some cases, but not for all plans. For a single patient case dosimetrically evaluated, minor dose differences were seen between the uncorrected and MAR plans (γ passing rate approximately 97%). The visual grading of patient images showed that MAR significantly improved image quality (P < 0.001).CONCLUSIONS:O-MAR and iMAR significantly improved image quality in terms of anatomical visualization for target and OAR delineation in dental implant patient images. WET calculations along several directions, all outside the metallic regions, showed that both uncorrected and MAR images contained metal artifacts which could potentially lead to unacceptable errors in proton treatment planning. ΔWET was reduced by MAR in some areas, while increased or unchanged deviations were seen for other path directions. The proton treatment plans created for the phantom images showed overall acceptable dose distributions differences when compared to the reference cases, both for the uncorrected and MAR images. However, substantial dose distribution differences in the areas of most severe artifacts were seen for some plans, which were reduced by MAR in some cases but not all. In conclusion, MAR could be beneficial to use for proton treatment planning; however, case-by-case evaluations of the metal artifact-degraded images are always recommended.

PurposeTo develop an infrastructure for structured and automated collection of interoperable radiation therapy (RT) data into a national clinical quality registry.Materials and methodsThe present study was initiated in 2012 with the participation of seven of the 15 hospital departments delivering RT in Sweden. A national RT nomenclature and a database for structured unified storage of RT data at each site (Medical Information Quality Archive, MIQA) have been developed. Aggregated data from the MIQA databases are sent to a national RT registry located on the same IT platform (INCA) as the national clinical cancer registries.ResultsThe suggested naming convention has to date been integrated into the clinical workflow at 12 of 15 sites, and MIQA is installed at six of these. Involvement of the remaining 3/15 RT departments is ongoing, and they are expected to be part of the infrastructure by 2016. RT data collection from ARIA®, Mosaiq®, Eclipse™, and Oncentra® is supported. Manual curation of RT-structure information is needed for approximately 10% of target volumes, but rarely for normal tissue structures, demonstrating a good compliance to the RT nomenclature. Aggregated dose/volume descriptors are calculated based on the information in MIQA and sent to INCA using a dedicated service (MIQA2INCA). Correct linkage of data for each patient to the clinical cancer registries on the INCA platform is assured by the unique Swedish personal identity number.ConclusionsAn infrastructure for structured and automated prospective collection of syntactically interoperable RT data into a national clinical quality registry for RT data is under implementation. Future developments include adapting MIQA to other treatment modalities (e.g. proton therapy and brachytherapy) and finding strategies to harmonize structure delineations. How the RT registry should comply with domain-specific ontologies such as the Radiation Oncology Ontology (ROO) is under discussion.