Cancer Incidence Related Definitions and Associated Formulas
This link shows formulas used to calculate rates with examples.
Childhood cancer - Cancer diagnosed in a person younger than 20
years of age. Rates are usually expressed as per 1 million when the ICCC system
Frequency - The number of new childhood cancer cases with a certain
type of cancer during a specific time period.
Rate - The number of new childhood cancer cases with a certain
type of cancer divided by the number of individuals under 20 years of age in that
Crude Rate - The number of new childhood cancer cases during a
specific time period per 1,000,000 individuals who are susceptible to childhood
cancer. There is no consideration (adjustment) given to the age factor.
Age-specific rate - The number of new childhood cancer cases diagnosed
per 1,000,000 individuals over a specific time period for a specific age group.
Age-adjusted rate - Cancer rates vary with age, and populations
vary by their age distributions. Age adjustment allows for comparison of rates between
different populations with different age structure. The "effect of age"
is no longer present upon age-adjustment. Age-adjusted rates are calculated using
the age distribution of the 1970 or 2000 US standard population, and for childhood
cancers when using ICCC classification, these are usually expressed per 1,000,000
Incidence - The number of new childhood cancer cases diagnosed
during a specific time period (i.e. one year).
95% Confidence Intervals - The formulas used to calculate the 95% confidence intervals
is R + 619.81*(R/D)1/2
Where R = crude childhood cancer incidence rate, D = population denominator, and
When frequencies are less than 100 then 95% confidence intervals are calculated
using the formulas provided on pages 98-102 in the
NCHS 2001 Birth Report a pdf document.
Rate Calculations With Small Numbers - There are variations in
all statistics that are the result of chance. This characteristic is of particular
importance in classifications with small numbers of events where small variations
are proportionately large in relation to the base figure. As an example, small changes
in the number of deaths or births in small population areas or in the number of
deaths from uncommon causes could result in large changes in these crude rates.
For this reason, rates for counties with small populations or other small bases
should be used cautiously.
Race - Race is reported as White, Black, Other, and Unknown. Other
race group includes Asian, Pacific Islander, and Native Americans.
Age - Age at diagnosis
Population Data - With the exception of population data by race
and population data for selected age groups of teens, the 2000 Census data, provided
by the Office of Research and Statistics (South Carolina Budget and Control Board),
were used to calculate the rates in this report. Population data by race and for
selected age groups were modified. Age Adjusted rates use 18 age groups and the
corresponding 18 standard weights from the 1970 and 2000 U.S. population.
Population Data By Race - The U.S. Census Bureau Population data
contains data for both "multiple race", and single race categories. This
presents problems for calculating vital statistical rates. The following methodology
was developed jointly by Office of Research and Statistics, South Carolina State
Budget and Control Board and the Division of Biostatistics and Health GIS, Public
Health Statistics and Information Services, SCDHEC.
The populations of these two race categories were allocated to the standard single
race categories by age, gender and county. This allocation was based on the proportional
distribution of the population of the standard single race categories within each
of these age, gender, county groups.
Population Data For Selected Age Groups - For inter-census years,
ORS provides estimated population data for South Carolina by age for five-year age
groups. It is assumed that the population within each of these age categories is
distributed uniformly through out the age interval. Based on this assumption, the
population for females 14-17, 15-17 and 18-19 years is derived, consecutively, as
follows - (20% of the female population 10-14 years plus 60% of the female population
15-19 years), (60% of the female population 15-19), and (40% of the female population
Residence Data - Data allocated to the place in South Carolina
where the person lived at time of diagnosis.
CLASSIFICATION OF CHILDHOOD CANCERS
Classification of Childhood Cancers - The types and distribution
of childhood cancer differ from those occurring in adult populations. The International
Association of Cancer Registries (IACR) has established a unique system for categorizing
childhood cancers, the International Classification of Childhood Cancer (ICCC).
Whereas adult cancers are usually organized by site of the primary tumor, childhood
cancers are classified according to their histology (microscopic identification
of cells and tissue).
a. Lymphoid leukemia
b. Acute non-lymphocytic leukemia
c. Chronic myeloid leukemia
d. Other specified leukemia
e. Unspecified leukemia
II. Lymphomas and Other Reticuloendothelial Neoplasms
a. Hodgkin’s disease
b. Non-Hodgkin’s disease
c. Burkitt’s lymphoma
d. Other reticuloendothelial neoplasms
e. Unspecified lymphomas
III. Central Nervous System and Miscellaneous Intracranial and
c. Primitive neuroectodermal tumors
d. Other gliomas
e. Miscellaneous intracranial and intraspinal neoplasms
f. Unspecified intracranial and intraspinal neoplasms
IV. Sympathetic Nervous System Tumors
a. Neuroblastoma and ganglioneuroblastoma
b. Other sympathetic nervous system tumors
VI. Renal Tumors
a. Wilms’ tumor, rhabdoid and clear cell sarcoma
b. Renal carcinoma
c. Unspecified malignant renal tumors
VII. Hepatic Tumors
b. Hepatic carcinoma
c. Unspecified malignant hepatic tumors
VIII. Malignant Bone Tumors
c. Ewing’s sarcoma
d. Other specified malignant bone tumors
e. Unspecified malignant bone tumors
IX. Soft-Tissue Sarcomas
a. Rhabdomyosarcoma and embryonal sarcoma
b. Fibrosarcoma, neurofibrosarcoma and other neurofibromatous neoplasms
c. Kaposi’s sarcoma
d. Other specified soft-tissue sarcomas
e. Unspecified soft-tissue sarcomas
X. Germ Cell, Trophoblastic and Other Gonadal Neoplasms
a. Intracranial and intraspinal germ cell tumors
b. Other and unspecified non-gonadal germ cell tumors
c. Gonadal germ cell tumors
d. Gonadal carcinomas
e. Other and unspecified malignant gonadal tumors
XI. Carcinomas and Other Malignant Epithelial Neoplasms
a. Adrenocortical carcinoma
b. Thyroid carcinoma
c. Nasopharyngeal carcinoma
d. Malignant melanoma
e. Skin carcinoma
f. Other and unspecified carcinomas
XII. Other and Unspecified Malignant Neoplasms
a. Other specified malignant tumors
b. Other unspecified malignant tumors
Stage at diagnosis - The extent of disease spread from the organ
of origin at time of diagnosis. The SCCCR uses the SEER General Summary Staging
System. This system includes five stages: in situ, localized, regional, distant,
and unstaged. In situ and localized are classified as "early stage." Regional
and distant are considered "late stage." Cancers diagnosed as in situ
are considered pre-invasive. Localized, regional, and distant staged cancers are
In situ stage - Classification for pre-invasive malignancies, those
that do not invade the basement membrane.
Invasive stage - Classification for invasive malignancies, those
that invade the basement membrane.
Localized stage - Classification for invasive malignancies that
are confined to the organ of origin.
Regional stage - Classification for cancer spread by direct extension
to adjacent organs or tissues, and/or spread to lymph nodes considered regional
to the organ of origin, but no further spread has occurred.
Distant stage - Classification of cancer spread beyond adjacent
organs or tissues, and/or metastasis to distant lymph nodes or tissues.
Unstaged - Classification resulting from insufficient information
available to determine stage of disease at diagnosis
Early stage - Grouping which includes in situ and localized stages
Late stage - Grouping which includes regional and distant stages
Cancer Grade - Grade is a 4-point scaling system determined by
a pathologist to describe the degree of differentiation of cancer cells. Differentiation
describes how abnormal the cells look under a microscope and probable rate of tumor
growth and spread. Well-differentiated, Grade 1 or low grade tissues often look
the most like normal cells; where as undifferentiated, Grade 4 or high grade tissues
often look the least like normal cells. In this module there are 9 grades possible
they are: Well Differentiated, Moderately Differentiated, Poorly Differentiated,
Undifferentiated, T-Cell, B-Cell, Null Cell, Natural Killer, and Not Determined.
SOURCES OF INFORMATION
Centers for Disease Control (CDC) - Located in Atlanta, GA, the
CDC is an agency of the Department of Health and Human Services. The CDC serves
as the national focus for developing and applying disease prevention and control,
environmental health, and health promotion and education activities designed to
improve the health of people of the United States.
National Program of Cancer Registries (NPCR) - Funded by the CDC,
the NPCR is a population-based system of cancer registries established in 1992 by
the Central Cancer Registries Amendment Act (Public Law 102-515). When fully implemented,
programs funded by the NPCR will collect data on cancer for 96% of the US population.
Surveillance, Epidemiology and End Results (SEER) - Program of
the National Cancer Institute that collects and publishes cancer incidence and survival
data from 11 population-based cancer registries and three supplemental registries
covering approximately 14 percent of the United States population.
Cancer site - The body organ or system where cancer originates;
the anatomical site of origin.
Metastasis - Movement of disease from one organ or part to another
not directly connected.
Risk factor - Anything that increases a person's chances of getting
a disease. Examples include smoking, diet, and age.
Cancer cluster - A group of more cancer cases than normal in a
small area, like a neighborhood, or within a short time period. Cancer clusters
are reported when people learn that an unusual number of their friends, family,
neighbors or co-workers have cancer.
COUNTIES BY REGIONS
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