Incidence Data Sources

Data from the registries participating in the National Program of Cancer Registries (NPCR) were reported to the Centers for Disease Control and Prevention (CDC) as of November 30, 2017. Data from registries in the Surveillance, Epidemiology, and End Results (SEER) Programexternal icon were reported to the National Cancer Institute (NCI)external icon as of November 1, 2018, and made available through the SEER Program limited-use data fileexternal icon released in April 2018. Data from California, Georgia, Idaho, Kentucky, Louisiana, Massachusetts, and New York (states that are supported by both NPCR and SEER) are presented as reported to CDC as of November 30, 2018.

How Incidence Data Are Collected

The primary source of data on cancer incidence is medical records. Staff at health care facilities abstract data from patients’ medical records, enter it into the facility’s own cancer registry if it has one, and then send the data to the regional or state registry. Both NPCR and SEER registries collect data using uniform data items and codes as documented by the North American Association of Central Cancer Registries (NAACCR).external icon This uniformity ensures that data items collected by the two federal programs are comparable.1 2 Information on primary site and histology was coded according to the International Classification of Diseases for Oncology, Third Edition (ICD-O-3)3 and categorized according to the revised SEER recodesexternal icon dated January 27, 2003, which define standard groupings of primary cancer sites. Beginning with 2010 diagnoses, cases are coded based on ICD-O-3 updated for hematopoietic codes based on WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (2008).

Reportable Cases

NPCR and SEER cancer registries consider as reportable all incident cases with a behavior code of 2 (in situ, noninvasive) or 3 (invasive, primary site only) in the ICD-O-3 with the exception of in situ cancer of the cervix. Basal and squamous cell carcinomas of the skin are also excluded, with the exception of those on the skin of the genital organs.3 Several cancers are coded as malignant in ICD-O-3 (beginning with 2001 diagnoses) that were not coded as malignant in ICD-O-23 and are noted as follows—

  • Myelodysplastic syndrome (MDS) including refractory anemias (histology codes 9980, 9982–9984, 9989) are included in the “Miscellaneous” and “All Sites” categories.
  • Chronic myeloproliferative disease (CMPD) including polycythemia vera and thrombocythemias (histology codes 9950, 9960–9962) are included in the “Miscellaneous” and “All Sites” categories.
  • Papillary ependymomas (9393) and papillary meningiomas (9538)—cancers that occur in the central nervous system—are included in the “Brain and Central Nervous System” and “All Sites” categories.
  • Some endometrial tumors (8931) are reported in the “Corpus and Uterus, NOS” and “All Sites” categories.

For comparisons with ICD-O-2 for cancers diagnosed prior to 2001, exclude all of the histology codes described above and listed as follows: 8931, 9393, 9538, 9950, 9960–9962, 9980, 9982–9984, 9989, 9990, 9991, 9992.3

Additional changes in ICD-O-3 apply to ovarian cancer: low malignant potential tumors (8442, 8451, 8462, 8472, 8473) of the ovary are no longer coded as malignant. Therefore, these cancers are not accounted for in the calculations of the incidence rate for ovarian cancer included in tables and figures. A footnote is provided as a reminder of this exclusion.

Pilocytic astrocytomas (9421) are also not coded as malignant in ICD-O-3, but these cancers are included in this report.

Impact of Hurricanes Katrina and Rita on Presenting Cancer Incidence Data

The population of many counties along the Gulf Coast of Louisiana, Alabama, Mississippi, and Texas were displaced in the fall of 2005 by Hurricanes Katrina and Rita, resulting in incomplete case ascertainment for the latter half of the year.

For these states, state- and county-level incidence rates were calculated based upon the data as it was submitted to CDC. Incidence rates in the Data Visualizations tool may differ from those published by the SEER program for Louisiana,external icon because the SEER program used only the first six months of incidence data for 2005 coupled with half of the population estimate for July 1, 2005, to calculate cancer incidence. Rates for the U.S. Census divisions and regions that include these states are calculated based on the data as submitted to CDC.

Childhood Cancer

Incidence data on childhood cancer are published in two formats—

  • The first is according to the SEER modification of the third edition of the International Classification of Childhood Cancer. The ICCC-3 is based on ICD-O-3/WHO 2008 classification of Tumors of Haematopoietic and Lymphoid tissues.4 The ICCC presents childhood cancers in 12 groups classified primarily by morphology. The SEER modification,external icon which affects the classification of nervous system and bone tumors, was chosen for compatibility with other published data on rates of childhood cancer in the United States.
  • The second format is according to the SEER site recode, which is based primarily on cancer site; the incidence data are presented in this format to make them comparable with published mortality data. This format allows the incidence data for childhood cancers to be categorized in the same groups as adult cancers. Although these groupings are not as appropriate for children as they are for adults, they are necessary to allow comparisons between childhood incidence and childhood mortality.

In Situ Bladder and Breast Cancers

In situ bladder cancers were recoded to invasive bladder cancers because the information needed to distinguish between in situ and invasive bladder cancers is not always available or reliable. Counts and rates for in situ breast cancer cases among women are presented; these are reported separately and are not included in counts or rates for the “All Sites” category.

Unknown Sex, Age, or Race

Non-reportable cancers and cancers in patients of unknown sex or age were omitted from all calculations, but cases of unknown race were included in the “All Races” category.

Nonmalignant Brain and CNS Tumors

Incidence data on nonmalignant primary brain and central nervous system (CNS) tumors are available in the USCS Data Visualizations tool. Cancer registries began collecting information on nonmalignant brain and CNS tumors beginning with 2004 diagnoses. Data collection of these tumors is in accordance with Public Law 107-260, the Benign Brain Tumor Cancer Registries Amendment Act, which mandates that NPCR registries collect data on all brain and CNS tumors with a behavior code of 0 (benign) and those with a behavior code of 1 (borderline), in addition to in situ and malignant.5 SEER registries voluntarily agreed to incorporate registration of these tumors in their standard practices.5


  1. Fritz A, Ries LAG. The SEER Program Code Manual, Third Edition. Bethesda (MD): National Cancer Institute; 1998.
  2. Thornton ML, (ed). Standards for Cancer Registries Vol II: Data Standards and Data Dictionary, Record Layout Version 14, 18th edition. Springfield (IL): North American Association of Central Cancer Registries; 2013.
  3. Fritz A, Percy C, Jack A, Shanmugaratnam K, Sobin L, Parkin DM, Whelan S. International Classification of Diseases for Oncology, Third Edition. Geneva, Switzerland: World Health Organization; 2000.
  4. Hematopoietic codes based on WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (2008).
  5. McCarthy BJ, Kruchko C, and the Central Brain Tumor Registry of the United States. Consensus conference on cancer registration of brain and central nervous system tumors.external icon Neuro-oncology 2005;7(2):196–201.