The incidence date is the date of the first histological or cytological confirmation of the tumour. It cannot be later than the start of treatment. If treatment begins before histological confirmation, the incidence date is the date of clinical diagnosis. It must always fall within three months of the first clinical visit related to this tumour.
The incidence date is the date of the first histological or cytological confirmation of the tumour. It cannot be later than the start of treatment. If treatment begins before histological confirmation, the incidence date is the date of clinical diagnosis. It must always fall within three months of the first clinical visit related to this tumour.
Patient data
ink_ses
Median income in postal code area as a proxy for socioeconomic status (SES)
Available from 2010. Socioeconomic status (SES) reflects an individual's social position, which strongly influences health and is linked to life expectancy in good health. Research on SES and health typically uses indicators such as education, income, occupation, and material wealth. This variable uses income as a proxy for SES.
Income data by postal code area were obtained from Statistics Netherlands (CBS), with 2019 as the reference year, downloaded on 16 October 2023 via https://www.cbs.nl/nl-nl/dossier/nederland-regionaal/geografische-data
/gegevens-per-postcode.
Income is defined as the median disposable household income, adjusted for household size and composition. For each area, the median standardised household income was compared to the national distribution and classified into one of five groups: low, lower-middle, middle, upper-middle, or high. Income thresholds (in euros) are available at: https://www.cbs.nl/nl-nl/longread/diversen/2023/statistische-gegevens-per-vierkant-en-postcode-2022-2021-2020-2019/4-beschrijving-cijfers. Because postal code areas often have few households, CBS also
considered the 99% confidence interval of the median income. If this interval spans multiple groups, a new category was created to reflect the range (e.g., 'low to lower-middle'). Categories may partially overlap due to this approach. If the median income is based on fewer than 10 households, it is classified as 'unclassifiable'. CBS originally defined 12 income categories.
For this variable, these were reduced to three to simplify analysis and remove overlaps.
Key considerations:
- Income is a snapshot and does not reflect accumulated wealth.
- Data are aggregated by postal code area, which may include substantial variation.
- Household income is strongly age-dependent; analyses should compare individuals within the same age group.
- Median disposable income is considered valid for up to 10 years before and after the reference year (2019).
Selection of malignancies to specify in the request:
-Period: Previous and/or subsequent malignancies, or based on a defined timeframe before or around the incidence date.
-Type: All cancer types in the NCR, or all malignant/invasive (excluding skin BCC), or a selection of specific tumour types.
NKR database content with full availability:
Period: Nationwide complete from 1989.
Exclusion criteria:
- Patients residing abroad at the time of incidence
- Basal cell carcinomas of skin and lip
- Second primary invasive and second non-invasive squamous cell carcinomas of the skin
- Adenocarcinoma in situ/high-grade dysplasia of colon, rectosigmoid and rectum
- Carcinoma in situ of the cervix
- Benign/borderline tumours, except: CNS tumours from 2001, Borderline ovarian tumours, AL amyloidosis from 2017, Polymorphic PTLD
Refers to the NCR tumour classification based on site, morphology, and behaviour. For more information, see: https://iknl.nl/nkr/registratie/tumorindeling
Once a year, at the end of the first quarter, the NCR is linked to the Municipal Personal Records Database (GBA). The GBA is complete up to February of that year. Vital status reflects the status up to this date. For patients listed as alive in the GBA, the vital status date is the date up to which the GBA is complete. If a patient is recorded as deceased or emigrated, the vital status date is the date of death or emigration. Using this date and the incidence date, the interval between incidence and vital status (in days) is calculated.
Once a year, at the end of the first quarter, the NCR is linked to the Municipal Personal Records Database (GBA). The GBA is complete up to February of that year. Vital status reflects the status up to this date. For patients listed as alive in the GBA, the vital status date is the date up to which the GBA is complete. If a patient is recorded as deceased or emigrated, the vital status date is the date of death or emigration. Using this date and the incidence date, the interval between incidence and vital status (in days) is calculated.
Once a year, at the end of the first quarter, the NCR is linked to the Municipal Personal Records Database (GBA). The GBA is complete up to February of that year. Vital status reflects the status up to this date. For patients listed as alive in the GBA, the vital status date is the date up to which the GBA is complete. If a patient is recorded as deceased or emigrated, the vital status date is the date of death or emigration. Using this date and the incidence date, the interval between incidence and vital status (in days) is calculated.
The TNM classification uses the edition applicable at the time of incidence.
Meaning of the last character in pN:
S: Result based only on sentinel node examination (sn)
I: Isolated tumour cells (ITC)
M: Micrometastases (mi)
cstadium: The clinical stage is based on cTNM, which is derived from information available before (neo-adjuvant) treatment, including findings during surgery (if not treated neo-adjuvantly) that influence the treatment plan. Meaning of "X" (unknown): Stage cannot be calculated, e.g., TX/NX/M0. Meaning of "M" (missing): Indicates TNM not recorded, possibly due to incomplete registration or use of EoD staging instead of TNM. Meaning of "NVT" (not applicable): TNM staging does not apply to this tumour type for the given incidence period.
The TNM classification uses the edition (UICC) valid at the time of incidence:
1989–1992: 4th edition (TNM 4),
1993–1998: 4th edition, 2nd revision (TNM 4),
1999–2002: 5th edition (TNM 5),
2003–2009: 6th edition (TNM 6),
2010–2016: 7th edition (TNM 7),
2017–2014: 8th edition (TNM 8),
and from 2025: 9th edition (TNM 9).
pstadium: The pathological (post-surgical) stage is based on pT, pN and pM. In cases of pre-surgical therapy,
ypT and ypN are used. If no tumour remains after pre-surgical therapy, this is recorded as stage p=0.
pM: Indicates whether there is pathological confirmation of distant metastases. There may be distant metastases that are not pathologically confirmed, which are therefore not included in the calculation for this variable.
Meaning of "X" (unknown): Stage cannot be calculated, e.g., TX/NX/M0.
Meaning of "M" (missing): Indicates TNM not recorded, possibly due to incomplete registration or use of EoD staging instead of TNM.
Meaning of "NVT" (not applicable): TNM staging does not apply to this tumour type for the given incidence period.
The TNM classification uses the edition (UICC) valid at the time of incidence:
1989–1992: 4th edition (TNM 4),
1993–1998: 4th edition, 2nd revision (TNM 4),
1999–2002: 5th edition (TNM 5),
2003–2009: 6th edition (TNM 6),
2010–2016: 7th edition (TNM 7),
2017–2014: 8th edition (TNM 8),
and from 2025: 9th edition (TNM 9).
Stadium: Based on pTNM supplemented by cTNM to best reflect the actual stage at diagnosis. Priority is given to
pTNM values. If surgery did not occur, pTNM is unknown, or pre-surgical therapy was given (pTNM becomes ypTNM), cTNM values are used.
Meaning of "X" (unknown): Stage cannot be calculated, e.g., TX/NX/M0.
Meaning of "M" (missing): Indicates TNM not recorded, possibly due to incomplete registration or use of EoD staging instead of TNM.
Meaning of "NVT" (not applicable): TNM staging does not apply to this tumour type for the given incidence period.
Non-microscopic confirmation:
0 = death certificate only
1 = clinical examination only (medical history and physical)
2 = clinical diagnostic tests, exploratory surgery or autopsy (without microscopic confirmation)
4 = specific biochemical and/or immunological laboratory tests.
Microscopic confirmation:
5 = haematological (bone marrow cytology, e.g., bone marrow aspiration, blood smear) or cytological confirmation of primary tumour or metastases, or definite microscopic confirmation but unclear whether cytology or histology
6 = histological confirmation of metastases only, including at autopsy
7 = histological confirmation of primary tumour, or unclear whether histology refers to primary tumour or
metastasis, including autopsy with histology.
Available from 2016.
For multifocal (multiple) primary tumours removed in a single operation, the tumour with the highest stage is
recorded as the main site. This item captures the (sub-)location of the other tumour.
Available since 1989. The Lauren classification has been based on morphology data in the NCR since 2015. For 1989–2015, values were supplemented using pathology reports from Palga.
If metastases fall within the main groups (peritoneum, lung, bone, liver, brain, lymph node, or adrenal gland), they are counted as one location. All other metastases are counted by unique two-digit ICD-O locations. Between 2008 and 2014, not all locations were recorded for patients with more than three metastatic sites; for these patients, the number of metastatic sites is recorded as 77.
Available since 2008. Metastases in the adrenal gland (C74). Between 2008 and 2014, not all sites were recorded for patients with more than three metastatic sites; similarly for more than four sites in 2017/2018.
Available since 2008. Metastases in bone or bone marrow (C40, C41, C421). Between 2008 and 2014, not all sites were recorded for patients with more than three metastatic sites; similarly for more than four sites in 2017/2018.
Available since 2008. Brain metastases (C71). Between 2008 and 2014, not all sites were recorded for patients with more than three metastatic sites; similarly for more than four sites in 2017/2018.
The incidence date is defined as the date of the first histological or
cytological confirmation of the primary tumour.
The metastasis date refers to the first histological or cytological confirmation of the
metastasis. If histological confirmation does not occur within three
months, the clinical diagnosis date is used. Consequently, the
metastasis date may precede the primary tumour incidence date by up
to three months.
Available since 2008. Liver metastases (C22). Between 2008 and 2014, not all sites were recorded for patients with more than three metastatic sites; similarly for more than four sites in 2017/2018.
Available since 2008. Lung metastases excluding pleural metastases (C34). Between 2008 and 2014, not all sites were recorded for patients with more than three metastatic sites; similarly for more than four sites in 2017/2018.
Available since 2008. Metastases in non-regional lymph nodes (C77). Between 2008 and 2014, not all sites were recorded for patients with more than three metastatic sites; similarly for more than four sites in 2017/2018.
Available since 2008. Between 2008 and 2014, not all sites were recorded for patients with more than three metastatic sites; similarly for more than four sites in 2017/2018.
Available since 2008. All metastases in the (retro)peritoneum (C48). Between 2008 and 2014, not all sites were recorded for patients with more than three metastatic sites; similarly for more than four sites in 2017/2018.
Metastasis location according to ICD-O-3. Metastatic sites have been recorded nationwide since 2008. For distant metastases at more than three sites, C768 was coded up to 2014 to indicate more than three locations. In 2017/2018 C768 may indicate more than four locations.
Explanation for records where both cM and pM show no metastases despite metastatic sites being recorded at diagnosis: cTNM is based on information available before (neo-adjuvant) treatment, including findings during surgery (if not treated neo-adjuvantly) that influence the treatment plan. pM indicates whether pathological
confirmation exists for distant metastases. If metastases are detected during or after neo-adjuvant treatment, TNM is not updated, but metastasis locations are recorded.
If the dataset includes metastasis locations after progression: only new or enlarged metastases are recorded, not all existing ones. C809 is coded for clinical progression when the site is unknown.
Metastasis location according to ICD-O-3. Metastatic sites have been recorded nationwide since 2008. For distant metastases at more than three sites, C768 was coded up to 2014 to indicate more than three locations. In 2017/2018 C768 may indicate more than four locations.
Explanation for records where both cM and pM show no metastases despite metastatic sites being recorded at diagnosis: cTNM is based on information available before (neo-adjuvant) treatment, including findings during surgery (if not treated neo-adjuvantly) that influence the treatment plan. pM indicates whether pathological
confirmation exists for distant metastases. If metastases are detected during or after neo-adjuvant treatment, TNM is not updated, but metastasis locations are recorded.
If the dataset includes metastasis locations after progression: only new or enlarged metastases are recorded, not all existing ones. C809 is coded for clinical progression when the site is unknown.
MSI has been recorded since 2019 for all M1 patients receiving systemic therapy. From 2022, MSI is recorded for both M0 and M1 patients receiving systemic therapy.
Available from 2015 to 2022. The tumour epicentre is defined as the midpoint between the dental arch and the tumour's upper and lower boundaries. Distances are based on endoscopy reports. Recorded only for C15.5 to C16.1, not for C15.0 to C15.4 or C16.2 to C16.9.
The first hospital visited by the patient for symptoms related to the malignancy, and where, based on that visit, a (suspected) malignancy is determined.
Available since 2015. Includes CT, abdominal CT, thoracic CT, and neck CT. Note: CT scans are not routinely recorded in all hospitals, so this item may be unknown more often in some hospitals.
Complete from 2015; incomplete data available for incidence years 2012–2014. The incidence date is the date of the first histological or cytological confirmation of the primary tumour.
Complete from 2015. Partially filled (if a diagnostic laparoscopy is known) for incidence years 2012–2014, but diagnostic laparoscopies were not always recorded for these years. Therefore, only value 1/yes applies for these years.
Complete from 2015; incomplete data available for incidence years 2012–2014. The incidence date is the date of the first histological or cytological confirmation of the primary tumour.
Available since 2015. Note: Endoscopic ultrasound (EUS) is not routinely recorded in all hospitals, so this item may be unknown more often in some hospitals.
Available since 2015. In principle, the most recent MDT where a treatment decision was made is recorded. If no MDT was held before therapy started, the first MDT after therapy initiation is recorded. Specialist centre involvement is nationally available from 2018 and on a project basis from 2015. Note: MDT meetings are not routinely recorded in all hospitals, so this item may be unknown more often in some hospitals.
Available since 2015. In principle, the most recent multidisciplinary team meeting (MDT) where a treatment decision was made is recorded. Involvement of a specialist centre has been available since 2018. Note: MDT meetings are not routinely recorded in all hospitals, so this item may be unknown more often in some hospitals.
Available since 2015. Note: Oesophago-gastroscopy is not routinely recorded in all hospitals, so this item may be unknown more often in some hospitals.
Available since 2015. Includes PET and PET/CT scans. Note: PET scans are not routinely recorded in all hospitals, so this item may be unknown more often in some hospitals.
The yes/no variables for categories are summarised in cci_cat (0, 1, 2 or more) and cci (weighted score per
Charlson 1987), with some categories counted only once if both occur:
• Cerebrovascular disease and Hemiplegia
• Diabetes and Diabetes with end organ damage
• Mild liver disease and Moderate/severe liver disease
• Any tumour and Metastatic solid tumour
Alternative summary scoring methods may also be used.
Incomplete scores:
From 2019, registration aligns with the Charlson Comorbidity Index. Earlier records may lack complete
category data, leading to some misclassification, noted in the relevant variable.
Note: From 1995 to 2014, comorbidities were recorded only in the southern Netherlands. From 2015, coverage is sometimes national but not for all tumour types or years. Missing variables indicate no comorbidities recorded for that tumour.
Risk factors
cci_aids
AIDS (including HIV) according to the Charlson Comorbidity Index
The yes/no variables for categories are summarised in cci_cat (0, 1, 2 or more) and cci (weighted score per
Charlson 1987), with some categories counted only once if both occur:
• Cerebrovascular disease and Hemiplegia
• Diabetes and Diabetes with end organ damage
• Mild liver disease and Moderate/severe liver disease
• Any tumour and Metastatic solid tumour
Alternative summary scoring methods may also be used.
Incomplete scores:
From 2019, registration aligns with the Charlson Comorbidity Index. Earlier records may lack complete
category data, leading to some misclassification, noted in the relevant variable.
Note: From 1995 to 2014, comorbidities were recorded only in the southern Netherlands. From 2015, coverage is sometimes national but not for all tumour types or years. Missing variables indicate no comorbidities recorded for that tumour.
Since 2019, registration has been aligned with the Charlson Comorbidity Index. For earlier years, not all categories can be accurately determined. Up to around 2012: Cci_cvd did not include TIA but did include significant carotid stenosis (treated with carotid endarterectomy or carotid desobstruction). As a result, patients may have been incorrectly included or excluded from the cerebrovascular disease category.
From 2019 onwards, registration aligns with the Charlson Comorbidity Index For registrations from earlier years, not all categories can therefore be accurately determined. Up to around 2018: Diabetes managed by diet alone was included in the registration.
Since 2019, registration has been aligned with the Charlson Comorbidity Index. For earlier years, not all categories can be accurately determined. Up to around 2018: No distinction was made between mild and moderate or severe liver disease. These patients were all included under cci_liver1 instead of cci_liver2. This does not affect cci_cat but does affect category classification and CCI.
Since 2019, registration has been aligned with the Charlson Comorbidity Index. For earlier years, not all categories can be accurately determined. Up to around 2018: No distinction was made between mild and moderate or severe liver disease. These patients were all included under cci_liver1 instead of cci_liver2. This does not affect cci_cat but does affect classification into categories and the CCI index.
Previous or concurrent invasive/malignant cancers, excluding basal cell and squamous cell carcinomas of the skin, where the initial diagnosis occurred between five years before and 30 days after the diagnosis of this tumou
Previous or synchronous metastatic cancer diagnosed up to 30 days after the diagnosis of this tumour. The NCR does not have complete registration of metachronous metastases. For many tumour types, these have only been recorded systematically or project-based in recent years, so this variable may sometimes incorrectly show as 0.
Since 2019, registration has been aligned with the Charlson Comorbidity Index. For earlier years, not all categories can be accurately determined. Up to around 2012: Cci_mi also included angina pectoris, meaning patients may have been incorrectly included in this variable.
Since 2019, registration has been aligned with the Charlson Comorbidity Index. For earlier years, not all categories can be accurately determined. Up to around 2018: Cci_renal also included mild kidney disease, meaning patients may have been incorrectly included in the category moderate or severe renal disease.
WHO performance status before starting therapy. If the Karnofsky score is noted in the medical record, it is converted to WHO score as described in Ma et al. 2010 – Interconversion of three measures of performance status: An empirical analysis. Performance status has been recorded since 2015.
Determination of pre- and post-surgical therapy is based on the chronological order of procedures in the NCR. The first surgical resection is used as the reference point. Local surgical procedures (e.g. polypectomy, excision biopsy, TUR, photodynamic therapy, electrocautery, cryosurgery, radiofrequency ablation) are not included.
Both chemotherapy and radiotherapy were part of the treatment, and based on dates/types, this likely represents chemoradiation. The chemotherapy and radiotherapy components are also included in the variables for systemic chemotherapy and radiotherapy.
Available since 2010. Chemoradiation type is classified based on whether it was given preoperatively, postoperatively, or without resection. If no resection was performed, categories are <41.4 Gy, 41.4 Gy (CROSS protocol), and >41.4 Gy (including definitive chemoradiation at 50.4 Gy). From 2010 to 2014, radiotherapy dose was not routinely recorded in the NCR, so chemoradiation without resection during this period was almost always placed in the "dose unknown" category.
Additional resections are recorded alongside a specific surgical procedure when extra surgery was performed to achieve a potentially complete resection. This applies in cases of suspected tumour extension or removal of part of another organ or multiple additional organs.
Surgical technique for oesophagectomy has been available since 2015. For gastrectomy, surgical technique has been available since 2010; distinction between conversion and robot-assisted procedures has been available since 2015.
Specific resection codes have been available since 2010; before 2010, all were grouped under "other resections." From 2014, a distinction was made between transthoracic oesophagectomy according to McKeown and Ivor Lewis.
Determination of pre- and post-surgical therapy is based on the chronological order of procedures in the NCR. The first surgical resection is used as the reference point. Local surgical procedures (e.g. polypectomy, excision biopsy, TUR, photodynamic therapy, electrocautery, cryosurgery, radiofrequency ablation) are not included.
The PCI score has been available since 2023 and is taken from the MDT report. If PCI was not mentioned in the MDT report, it is based on the diagnostic laparoscopy report.
This variable refers to radiotherapy targeting the primary tumour.
Determination of pre- and post-surgical therapy is based on the chronological order of procedures in the NCR. The first surgical resection is used as the reference point. Local procedures (e.g. tumour destruction, excision biopsy, photodynamic therapy, electrocautery, cryosurgery, radiofrequency ablation) are not included.
Systemic therapies in the NCR are coded using the Anatomical Therapeutic Chemical (ATC) classification system. Recording of systemic therapy is not always specific; before 2015, non-specific codes were used more frequently.
The end date of chemotherapy is the day the final cycle is completed. If this date is unknown, the start date of the last cycle may be recorded as the end date. The incidence date is the date of the first histological or cytological confirmation of the primary tumour.
The end date of chemotherapy is the day the final cycle is completed. If this date is unknown, the start date of the last cycle may be recorded as the end date.
This variable refers to systemic targeted therapy, including immunotherapy.
Determination of pre- and post-surgical therapy is based on the chronological order of procedures in the NCR. The first surgical resection is used as the reference point. Local procedures (e.g. tumour destruction, excision biopsy, photodynamic therapy, electrocautery, cryosurgery, radiofrequency ablation) are not included.
Available since 2010. Patients are classified into a single category, choosing the lowest applicable category. From 2010 to 2014, radiotherapy dose was not routinely recorded in the NCR, so chemoradiation without resection during this period was almost always placed in the "dose unknown" category.