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Cancer Incidence Related Definitions and Associated Formulas

Statistical Terms Demographic Information Population Data Cancer Staging Cancer Grade

Sources of Information Miscellaneous Information Counties by Regions

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ANIMATED FORMULAS
This link shows formulas used to calculate rates with examples.

STATISTICAL TERMS

Crude rate - The number of new cases or deaths during a specific time period per 100,000 individuals. There is no consideration (adjustment) given to the age factor.

Age-specific rate - The number of new cases diagnosed per 100,000 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 2000 US standard population, and they are usually expressed per 100,000 population.

Mortality - The number of deaths occurring during a specific time period. Diagnosis may have occurred prior to that specific time period.

Incidence - The number of new cases diagnosed during a specific time period (i.e. one year).

Prevalence - A measure of the proportion of persons in a population with a certain disease at a given time. The SCCCR does not collect prevalence.

Five-year survival - The percentage of people with a given cancer who are expected to survive five years or longer with the disease.

95% Confidence Intervals r + 61.981*(r/n)^1/2
Where r = live birth rate, n = number of live births or population denominator, and 61.981=1.96*(1000)^1/2
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.

DEMOGRAPHIC INFORMATION

RaceInformation on race of the mother and father is reported on birth and fetal death certificates, and the race of the decedent is reported on death certificates. Fetal deaths are reported by race of mother. As of 1990, Live Births are reported by race of mother instead of race of child. This change allows South Carolina's birth data to be consistent with the National Center for Health Statistics and other states throughout the United States. 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 15-19).

RESIDENCE DATA: Data allocated to the place in South Carolina where the person normally resided, regardless of where the event occurred.

CANCER STAGING

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 invasive.

In situ stage - Classification for pre-invasive malignancies, those that do not 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 of disease.

Late stage - Grouping which includes regional and distant stages of disease.

CANCER GRADE

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.

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.

MISCELLANEOUS TERMS

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

Region 1  01 Abbeville 04 Anderson 19 Edgefield 24 Greenwood 30 Laurens 33 McCormick 37 Oconee 41 Saluda Region 2 11 Cherokee 23 Greenville 39 Pickens 42 Spartanburg 44 Union Region 3 12 Chester 20 Fairfield 29 Lancaster 32 Lexington 36 Newberry 40 Richland 46 York Region 4 13 Chesterfield 14 Claredon 16 Darlington 17 Dillon 21 Florence 28 Kershaw 31 Lee 34 Marion 35 Marlboro 43 Sumter

Region 5 02 Aiken 03 Allendale 05 Bamberg 06 Barnwell 09 Calhoune 38 Orangeburg Region 6 22 Georgetown 26 Horry 45 Williamsburg Region 7 08 Berkeley 10 Charleston 18 Dorchester Region 8 07 Beaufort 15 Colleton 25 Hampton 27 Jasper

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