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Engholm G, Lundberg FE, Kønig SM, Ólafsdóttir E, Johannesen TB, Pettersson D, Malila N, Mørch LS, Johansson AL, Friis S. TNM stage in the Nordic Cancer Registries 2004-2016: Registration and availability. Acta Oncol 2024; 63:303-312. [PMID: 38716485 PMCID: PMC11332511 DOI: 10.2340/1651-226x.2024.35232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 04/05/2024] [Indexed: 05/23/2024]
Abstract
BACKGROUND AND PURPOSE Stage at cancer diagnosis is an important predictor of cancer survival. TNM stage is constructed for anatomic solid cancer diagnoses from tumor size (T), nodal spread (N) and distant metastasis (M) and categorized in groups 0-I, II, II and IV. TNM stage is imperative in cancer diagnosis, management and control, and of high value in cancer surveillance, for example, monitoring of stage distributions. This study yields an overview of TNM availability and trends in stage distribution in the Nordic countries for future use in monitoring and epidemiologic studies. MATERIAL AND METHODS TNM information was acquired from the cancer registries in Denmark, Norway, Sweden, and Iceland during 2004-2016 for 26 cancer sites in the three former countries and four in Iceland. We studied availability, comparability, and distribution of TNM stage in three periods: 2004-2008, 2009-2013, and 2014-2016, applying a previously validated algorithm of 'N0M0 for NXMX'. For cancers of colon, rectum, lung, breast, and kidney, we examined TNM stage-specific 1-year relative survival to evaluate the quality in registration of TNM between countries. RESULTS Denmark, Sweden, and Iceland exhibited available TNM stage proportions of 75-95% while proportions were lower in Norway. Proportions increased in Sweden over time but decreased in Denmark. One-year relative survival differed substantially more between TNM stages than between countries emphasizing that TNM stage is an important predictor for survival and that stage recording is performed similarly in the Nordic countries. INTERPRETATION Assessment and registration of TNM stage is an imperative tool in evaluations of trends in cancer survival between the Nordic countries.
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Affiliation(s)
- Gerda Engholm
- Danish Cancer Institute, Danish Cancer Society, Copenhagen, Denmark.
| | - Frida E Lundberg
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Simon M Kønig
- Danish Cancer Institute, Cancer Epidemiology and Surveillance, Danish Cancer Society, Copenhagen, Denmark
| | | | | | - David Pettersson
- Swedish Cancer Registry, National Board of Health and Welfare, Stockholm, Sweden
| | - Nea Malila
- Finnish Cancer Registry, Helsinki, Finland
| | - Lina S Mørch
- Danish Cancer Institute, Cancer and Medicine, Danish Cancer Society, Copenhagen, Denmark
| | - Anna L.V. Johansson
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; Cancer Registry of Norway, Oslo, Norway
| | - Søren Friis
- Danish Cancer Institute, Cancer Epidemiology and Surveillance, Danish Cancer Society, Copenhagen, Denmark
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Lundberg FE, Birgisson H, Engholm G, Ólafsdóttir EJ, Mørch LS, Johannesen TB, Pettersson D, Lambe M, Seppä K, Lambert PC, Johansson ALV, Hölmich LR, Andersson TML. Survival trends for patients diagnosed with cutaneous malignant melanoma in the Nordic countries 1990-2016: The NORDCAN survival studies. Eur J Cancer 2024; 202:113980. [PMID: 38452724 DOI: 10.1016/j.ejca.2024.113980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 02/09/2024] [Accepted: 02/26/2024] [Indexed: 03/09/2024]
Abstract
BACKGROUND The survival in patients diagnosed with cutaneous malignant melanoma (CMM) has improved in the Nordic countries in the last decades. It is of interest to know if these improvements are observed in all ages and for both women and men. METHODS Patients diagnosed with CMM in the Nordic countries in 1990-2016 were identified in the NORDCAN database. Flexible parametric relative survival models were fitted, except for Iceland where a non-parametric Pohar-Perme approach was used. A range of survival metrics were estimated by sex, both age-standardised and age-specific. RESULTS The 5-year relative survival improved in all countries, in both women and men and across age. While the improvement was more pronounced in men, women still had a higher survival at the end of the study period. The survival was generally high, with age-standardised estimates of 5-year relative survival towards the end of the study period ranging from 85% in Icelandic men to 95% in Danish women. The age-standardised and reference-adjusted 5-year crude probability of death due to CMM ranged from 5% in Danish and Swedish women to 13% in Icelandic men. CONCLUSION Although survival following CMM was relatively high in the Nordic countries in 1990, continued improvements in survival were observed throughout the study period in both women and men and across age.
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Affiliation(s)
- Frida E Lundberg
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Sweden; Department of Oncology-Pathology, Karolinska Institutet, Sweden
| | | | | | | | | | | | - David Pettersson
- Swedish Cancer Registry, National Board of Health and Welfare, Sweden
| | - Mats Lambe
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Sweden
| | - Karri Seppä
- Finnish Cancer Registry, Finland; Faculty of Social Sciences, Tampere University, Finland
| | - Paul C Lambert
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Sweden; Biostatistics Research Group, Department of Health Sciences, University of Leicester, UK
| | - Anna L V Johansson
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Sweden; Cancer Registry of Norway, the Norwegian Institute of Public Health, Norway
| | | | - Therese M-L Andersson
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Sweden.
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Skaga E, Trewin-Nybråten CB, Niehusmann P, Johannesen TB, Marienhagen K, Oltedal L, Schipman S, Skjulsvik AJ, Solheim O, Solheim TS, Sundstrøm T, Vik-Mo EO, Petter Brandal, Ingebrigtsen T. Stable glioma incidence and increased patient survival over the past two decades in Norway: a nationwide registry-based cohort study. Acta Oncol 2024; 63:83-94. [PMID: 38501768 PMCID: PMC11332456 DOI: 10.2340/1651-226x.2024.24970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 02/08/2024] [Indexed: 03/20/2024]
Abstract
BACKGROUND Surveillance of incidence and survival of central nervous system tumors is essential to monitor disease burden and epidemiological changes, and to allocate health care resources. Here, we describe glioma incidence and survival trends by histopathology group, age, and sex in the Norwegian population. MATERIAL AND METHODS We included patients with a histologically verified glioma reported to the Cancer Registry of Norway from 2002 to 2021 (N = 7,048). Population size and expected mortality were obtained from Statistics Norway. Cases were followed from diagnosis until death, emigration, or 31 December 2022, whichever came first. We calculated age-standardized incidence rates (ASIR) per 100,000 person-years and age-standardized relative survival (RS). Results: The ASIR for histologically verified gliomas was 7.4 (95% CI: 7.3-7.6) and was higher for males (8.8; 95% CI: 8.5-9.1) than females (6.1; 95% CI: 5.9-6.4). Overall incidence was stable over time. Glioblastoma was the most frequent tumor entity (ASIR = 4.2; 95% CI: 4.1-4.4). Overall, glioma patients had a 1-year RS of 63.6% (95% CI: 62.5-64.8%), and a 5-year RS of 32.8% (95% CI: 31.6-33.9%). Females had slightly better survival than males. For most entities, 1- and 5-year RS improved over time (5-year RS for all gliomas 29.0% (2006) and 33.1% (2021), p < 0.001). Across all tumor types, the RS declined with increasing age at diagnosis. INTERPRETATION The incidence of gliomas has been stable while patient survival has increased over the past 20 years in Norway. As gliomas represent a heterogeneous group of primary CNS tumors, regular reporting from cancer registries at the histopathology group level is important to monitor disease burden and allocate health care resources in a population.
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Affiliation(s)
- Erlend Skaga
- Vilhelm Magnus Laboratory for Neurosurgical Research and Department of Neurosurgery, Oslo University Hospital, Oslo, Norway; Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA.
| | - Cassia B Trewin-Nybråten
- Department of Registration, Cancer Registry of Norway, Norwegian Institute of Public Health, Oslo, Norway
| | - Pitt Niehusmann
- Department of Pathology, Oslo University Hospital, Oslo, Norway
| | - Tom Børge Johannesen
- Department of Registration, Cancer Registry of Norway, Norwegian Institute of Public Health, Oslo, Norway
| | | | - Leif Oltedal
- Mohn Medical Imaging and Visualization Centre, Department of Radiology, Haukeland University Hospital, Bergen, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Stephanie Schipman
- Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway; Medical Faculty, University Hospital Muenster, Germany
| | - Anne Jarstein Skjulsvik
- Department of Pathology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway; Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
| | - Ole Solheim
- Department of Neurosurgery, St. Olavs University Hospital, Trondheim, Norway; Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Tora Skeidsvoll Solheim
- Cancer Clinic, St. Olavs University Hospital, Trondheim, Norway; Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
| | - Terje Sundstrøm
- Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Einar O Vik-Mo
- Vilhelm Magnus Laboratory for Neurosurgical Research and Department of Neurosurgery, Oslo University Hospital, Oslo, Norway; Institute for Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Petter Brandal
- Department of Oncology, Division of Cancer Medicine, Oslo University Hospital, Oslo, Norway; Institute for Cancer Genetics and Informatics, Oslo University Hospital, Oslo, Norway
| | - Tor Ingebrigtsen
- Department of Clinical Medicine, Faculty of Health Sciences, UiT the Arctic University of Norway, Tromsø, Norway; Department of Neurosurgery, Otorhinolaryngology and Ophthalmology, University Hospital of North Norway, Tromsø, Norway
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Lee S, Lambert PC, Sweeting MJ, Latimer NR, Rutherford MJ. Evaluation of Flexible Parametric Relative Survival Approaches for Enforcing Long-Term Constraints When Extrapolating All-Cause Survival. VALUE IN HEALTH : THE JOURNAL OF THE INTERNATIONAL SOCIETY FOR PHARMACOECONOMICS AND OUTCOMES RESEARCH 2024; 27:51-60. [PMID: 37858887 DOI: 10.1016/j.jval.2023.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 09/28/2023] [Accepted: 10/02/2023] [Indexed: 10/21/2023]
Abstract
OBJECTIVES Parametric models are used to estimate the lifetime benefit of an intervention beyond the range of trial follow-up. Recent recommendations have suggested more flexible survival approaches and the use of external data when extrapolating. Both of these can be realized by using flexible parametric relative survival modeling. The overall aim of this article is to introduce and contrast various approaches for applying constraints on the long-term disease-related (excess) mortality including cure models and evaluate the consequent implications for extrapolation. METHODS We describe flexible parametric relative survival modeling approaches. We then introduce various options for constraining the long-term excess mortality and compare the performance of each method in simulated data. These methods include fitting a standard flexible parametric relative survival model, enforcing statistical cure, and forcing the long-term excess mortality to converge to a constant. We simulate various scenarios, including where statistical cure is reasonable and where the long-term excess mortality persists. RESULTS The compared approaches showed similar survival fits within the follow-up period. However, when extrapolating the all-cause survival beyond trial follow-up, there is variation depending on the assumption made about the long-term excess mortality. Altering the time point from which the excess mortality is constrained enables further flexibility. CONCLUSIONS The various constraints can lead to applying explicit assumptions when extrapolating, which could lead to more plausible survival extrapolations. The inclusion of general population mortality directly into the model-building process, which is possible for all considered approaches, should be adopted more widely in survival extrapolation in health technology assessment.
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Affiliation(s)
- Sangyu Lee
- Biostatistics Research Group, Department of Population Health Sciences, University of Leicester, Leicester, England, UK.
| | - Paul C Lambert
- Biostatistics Research Group, Department of Population Health Sciences, University of Leicester, Leicester, England, UK; Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Michael J Sweeting
- Biostatistics Research Group, Department of Population Health Sciences, University of Leicester, Leicester, England, UK; Statistical Innovation, Oncology Biometrics, AstraZeneca, Cambridge, England, UK
| | - Nicholas R Latimer
- School of Health and Related Research, University of Sheffield, Sheffield, England, UK
| | - Mark J Rutherford
- Biostatistics Research Group, Department of Population Health Sciences, University of Leicester, Leicester, England, UK
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Trewin-Nybråten CB, Larsen IK, Møller B, Heikkilä R. Hospital surgical volume and colorectal cancer survival in Norway: A nationwide cohort study. Cancer Epidemiol 2023; 85:102404. [PMID: 37343490 DOI: 10.1016/j.canep.2023.102404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 06/13/2023] [Accepted: 06/16/2023] [Indexed: 06/23/2023]
Abstract
BACKGROUND Studies of hospital surgical volume and colorectal cancer survival are inconclusive. We investigated whether surgical volume was associated with survival of patients operated for colorectal cancer in Norway. METHODS Using Cancer Registry of Norway data, we compared excess mortality from colorectal cancer by hospital surgical volume among 26,989 colon and 9779 rectal cancer patients diagnosed 2009-2020 and followed-up to 31.12.2021. Hospitals were divided into terciles according to their three-year average annual surgical volume; colon: low (< 22), middle (22-73), high (> 73); rectal: low (< 17), middle (17-38), high (> 38). We estimated excess hazard ratios (EHR) with flexible parametric models adjusted for age, year, stage, surgical urgency and surgery location (within/outside patient's residential health trust). RESULTS Low-volume hospitals had the highest proportion of late-stage or acutely operated colon cancer patients. Colon cancer patients operated at low- versus high-volume hospitals had significantly increased crude excess mortality (EHR = 1.30; 95 % CI = 1.14-1.48) but no difference after adjustment for age, year, and stage (EHR = 0.97; 0.85-1.11). High-volume hospitals had the highest proportion of late-stage rectal cancer patients and patients operated outside their residential area. Rectal cancer patients operated at low- versus high-volume hospitals did not have significantly different excess mortality before (EHR = 0.84; 0.64-1.10) or after (EHR = 1.03; 0.79-1.35) adjustment for age, year, stage, surgical urgency and surgery location. After accounting for case-mix, hospital surgical volume was not associated with excess mortality from colon (P = 0.40) or rectal cancer (P = 0.22). CONCLUSION Low hospital surgical volume was not associated with poorer colorectal cancer survival.
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Affiliation(s)
- Cassia B Trewin-Nybråten
- Department of Registration, Cancer Registry of Norway, P.O. Box 5313 Majorstuen, N-0304 Oslo, Norway.
| | - Inger Kristin Larsen
- Department of Registration, Cancer Registry of Norway, P.O. Box 5313 Majorstuen, N-0304 Oslo, Norway
| | - Bjørn Møller
- Department of Registration, Cancer Registry of Norway, P.O. Box 5313 Majorstuen, N-0304 Oslo, Norway
| | - Reino Heikkilä
- Department of Oncology, Oslo University Hospital, P.O. Box 4950 Nydalen, 0424 Oslo, Norway
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Kristiansen MF, Mikkelsen RM, Kristiansdóttir T, Andórsdóttir G, Hansen SÓ, Á Steig B, Nielsen KR, Skaalum Petersen M, Strøm M. Cancer survival in the Faroe Islands over the last 50 years compared to the other Nordic countries. Int J Cancer 2023; 152:2090-2098. [PMID: 36727543 DOI: 10.1002/ijc.34456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 12/22/2022] [Accepted: 01/09/2023] [Indexed: 02/03/2023]
Abstract
As sustained development in cancer treatment protocols have led to improved survival in most areas of the world, surveillance is needed to ensure that small populations follow suit. Our study reports age-standardized relative cancer survival in the Faroe Islands compared to the other Nordic countries. We present 1- and 5-year survival estimates and corresponding 95% confidence intervals for the Faroe Islands and compare them with estimates for the Nordic countries. The data for this article has been obtained through the NORDCAN collaboration (2019 data). Age-standardized relative survival was estimated using shared R codes on individual-level data within each country. Ten-year calendar inclusion periods were used in addition to the usual 5-year calendar periods to include cancer sites with few cases, which is especially beneficial to the smaller populations. The primary findings were that 1- and 5-year survival were consistently lower in the Faroes for the summary group all sites but non-melanoma skin cancer for both women and men. Further, 5-year survival was lower for women with ovarian cancer and men with lung cancer than in other Nordic countries. Previously, breast cancer survival was low in the Faroes but has improved to a comparable level over the last few years. Colorectal cancer survival was relatively high for both sexes. The reported estimates in this article call for further research to investigate the cancers with lower survival and should call for actions to improve the survival of Faroese cancer patients.
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Affiliation(s)
- Marnar Fríðheim Kristiansen
- Medical Department, National Hospital of the Faroe Islands, Tórshavn, Faroe Islands.,The Faroese Cancer Registry, National Hospital of the Faroe Islands, Tórshavn, Faroe Islands.,Centre of Health Sciences, University of the Faroe Islands, Tórshavn, Faroe Islands.,Genetic Biobank of the Faroe Islands, Tórshavn, Faroe Islands
| | | | | | | | - Saeunn Ólavsdóttir Hansen
- Medical Department, National Hospital of the Faroe Islands, Tórshavn, Faroe Islands.,The Faroese Cancer Registry, National Hospital of the Faroe Islands, Tórshavn, Faroe Islands
| | - Bjarni Á Steig
- Medical Department, National Hospital of the Faroe Islands, Tórshavn, Faroe Islands.,The Faroese Cancer Registry, National Hospital of the Faroe Islands, Tórshavn, Faroe Islands.,Genetic Biobank of the Faroe Islands, Tórshavn, Faroe Islands
| | - Kári Rubek Nielsen
- Medical Department, National Hospital of the Faroe Islands, Tórshavn, Faroe Islands.,The Faroese Cancer Registry, National Hospital of the Faroe Islands, Tórshavn, Faroe Islands.,Genetic Biobank of the Faroe Islands, Tórshavn, Faroe Islands
| | - Maria Skaalum Petersen
- Centre of Health Sciences, University of the Faroe Islands, Tórshavn, Faroe Islands.,Department of Occupational Medicine and Public Health, The Faroese Hospital System, Tórshavn, Faroe Islands
| | - Marin Strøm
- Centre of Health Sciences, University of the Faroe Islands, Tórshavn, Faroe Islands.,Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark
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Rutherford MJ, Andersson TML, Myklebust TÅ, Møller B, Lambert PC. Non-parametric estimation of reference adjusted, standardised probabilities of all-cause death and death due to cancer for population group comparisons. BMC Med Res Methodol 2022; 22:2. [PMID: 34991487 PMCID: PMC8740504 DOI: 10.1186/s12874-021-01465-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 11/08/2021] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Ensuring fair comparisons of cancer survival statistics across population groups requires careful consideration of differential competing mortality due to other causes, and adjusting for imbalances over groups in other prognostic covariates (e.g. age). This has typically been achieved using comparisons of age-standardised net survival, with age standardisation addressing covariate imbalance, and the net estimates removing differences in competing mortality from other causes. However, these estimates lack ease of interpretability. In this paper, we motivate an alternative non-parametric approach that uses a common rate of other cause mortality across groups to give reference-adjusted estimates of the all-cause and cause-specific crude probability of death in contrast to solely reporting net survival estimates. METHODS We develop the methodology for a non-parametric equivalent of standardised and reference adjusted crude probabilities of death, building on the estimation of non-parametric crude probabilities of death. We illustrate the approach using regional comparisons of survival following a diagnosis of rectal cancer for men in England. We standardise to the covariate distribution and other cause mortality of England as a whole to offer comparability, but with close approximation to the observed all-cause region-specific mortality. RESULTS The approach gives comparable estimates to observed crude probabilities of death, but allows direct comparison across population groups with different covariate profiles and competing mortality patterns. In our illustrative example, we show that regional variations in survival following a diagnosis of rectal cancer persist even after accounting for the variation in deprivation, age at diagnosis and other cause mortality. CONCLUSIONS The methodological approach of using standardised and reference adjusted metrics offers an appealing approach for future cancer survival comparison studies and routinely published cancer statistics. Our non-parametric estimation approach through the use of weighting offers the ability to estimate comparable survival estimates without the need for statistical modelling.
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Affiliation(s)
- Mark J Rutherford
- Department of Health Sciences, University of Leicester, Leicester, UK.
| | | | - Tor Åge Myklebust
- Department of Registration, Cancer Registry of Norway, Oslo, Norway
- Department of Research and Innovation, Møre and Romsdal Hospital Trust, Ålesund, Norway
| | - Bjørn Møller
- Department of Registration, Cancer Registry of Norway, Oslo, Norway
| | - Paul C Lambert
- Department of Health Sciences, University of Leicester, Leicester, UK
- Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
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Møller B, Jerm MB, Larønningen S, Johannesen TB, Seglem AH, Larsen IK, Myklebust TÅ. The validity of cancer information on death certificates in Norway and the impact of death certificate initiated cases on cancer incidence and survival. Cancer Epidemiol 2021; 75:102023. [PMID: 34560362 DOI: 10.1016/j.canep.2021.102023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/27/2021] [Accepted: 09/06/2021] [Indexed: 12/12/2022]
Abstract
BACKGROUND Death certificates are an important source of information for cancer registries. The aim of this study was to validate the cancer information on death certificates, and to investigate the effect of including death certificate initiated (DCI) cases in the Cancer Registry of Norway when estimating cancer incidence and survival. METHODS All deaths in Norway in the period 2011-2015 with cancer mentioned on the death certificates were linked to the cancer registry. Notifications not registered from other sources were labelled death certificate notifications (DCNs), and considered as either cancer or not, based on available information in the registry or from trace-back to another source. RESULTS From the total of 65 091 cancers mentioned on death certificates in the period 2011-2015, 58,425 (89.8%) were already in the registry. Of the remaining 6 666 notifications, 2 636 (2 129 with cancer as underlying cause) were not regarded to be new cancers, which constitutes 4.0% of all cancers mentioned on death certificates and 39.5% of the DCNs. Inclusion of the DCI cases increased the incidence of all cancers combined by 2.6%, with largest differences for cancers with poorer prognosis and for older age groups. Without validation, including the 2 129 disregarded death certificates would over-estimate the incidence by 1.3%. Including DCI cases decreased the five-year relative survival estimate for all cancer sites combined with 0.5% points. CONCLUSION In this study, almost 40% of the DCNs were regarded not to be a new cancer case, indicating unreliability of death certificate information for cancers that are not already registered from other sources. The majority of the DCNs where, however, registered as new cases that would have been missed without death certificates. Both including and excluding the DCI cases will potentially bias the survival estimates, but in different directions. This biases were shown to be small in the Cancer Registry of Norway.
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Affiliation(s)
- Bjørn Møller
- Department of Registration, Cancer Registry of Norway, Oslo, Norway.
| | | | - Siri Larønningen
- Department of Registration, Cancer Registry of Norway, Oslo, Norway
| | | | - Ann Helen Seglem
- Department of Registration, Cancer Registry of Norway, Oslo, Norway
| | | | - Tor Åge Myklebust
- Department of Registration, Cancer Registry of Norway, Oslo, Norway; Department of Research and Innovation, Møre and Romsdal Hospital Trust, Ålesund, Norway
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Lambert PC, Syriopoulou E, Rutherford MR. Direct modelling of age standardized marginal relative survival through incorporation of time-dependent weights. BMC Med Res Methodol 2021; 21:84. [PMID: 33894741 PMCID: PMC8070293 DOI: 10.1186/s12874-021-01266-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 04/05/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND When quantifying the probability of survival in cancer patients using cancer registration data, it is common to estimate marginal relative survival, which under assumptions can be interpreted as marginal net survival. Net survival is a hypothetical construct giving the probability of being alive if it was only possible to die of the cancer under study, enabling comparisons between populations with differential mortality rates due to causes other the cancer under study. Marginal relative survival can be estimated non-parametrically (Pohar Perme estimator) or in a modeling framework. In a modeling framework, even when just interested in marginal relative survival it is necessary to model covariates that affect the expected mortality rates (e.g. age, sex and calendar year). The marginal relative survival function is then obtained through regression standardization. Given that these covariates will generally have non-proportional effects, the model can become complex before other exposure variables are even considered. METHODS We propose a flexible parametric model incorporating restricted cubic splines that directly estimates marginal relative survival and thus removes the need to model covariates that affect the expected mortality rates. In order to do this the likelihood needs to incorporate the marginal expected mortality rates at each event time taking account of informative censoring. In addition time-dependent weights are incorporated into the likelihood. An approximation is proposed through splitting the time scale into intervals, which enables the marginal relative survival model to be fitted using standard software. Additional weights can be incorporated when standardizing to an external reference population. RESULTS The methods are illustrated using national cancer registry data. In addition, a simulation study is performed to compare different estimators; a non-parametric approach, regression-standardization and the new marginal relative model. The simulations study shows the new approach is unbiased and has good relative precision compared to the non-parametric estimator. CONCLUSION The approach enables estimation of standardized marginal relative survival without the need to model covariates that affect expected mortality rates and thus reduces the chance of model misspecification.
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Affiliation(s)
- Paul C. Lambert
- Biostatistics Research Group, Department of Health Sciences, University of Leicester, University Road, Leicester, UK
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Nobels Väg 12A, Stockholm, Sweden
| | - Elisavet Syriopoulou
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Nobels Väg 12A, Stockholm, Sweden
| | - Mark R. Rutherford
- Biostatistics Research Group, Department of Health Sciences, University of Leicester, University Road, Leicester, UK
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