The New Jersey State Cancer Registry
The objectives of the New Jersey State Cancer Registry (NJSCR) are to:
The New Jersey State Cancer Registry is a population-based incidence registry that serves the entire state of New Jersey, with a population of approximately eight million people. The NJSCR was established by legislation (NJSA 26:2-104 et. seq.) and includes all cases of cancer diagnosed in New Jersey residents since October 1, 1978. New Jersey regulations (NJAC 8:57A) require the reporting of all newly diagnosed cancer cases to the NJSCR within three months of hospital discharge or six months of diagnosis, whichever is sooner. Reports are filed by hospitals, diagnosing physicians, dentists, and independent clinical laboratories. Every hospital in New Jersey is now reporting cancer cases electronically. In addition, reporting agreements are maintained with New York, Pennsylvania, Delaware, Florida, and other states so that New Jersey residents diagnosed with cancer outside the state can be identified.
All primary invasive and in situ neoplasms, except certain carcinomas of the skin and cervical cancer in situ diagnosed after 1994, are reportable to the NJSCR. The information collected by the NJSCR includes basic patient identification, demographic characteristics of the patient, medical information on each cancer diagnosis (such as the anatomic site, histologic type and summary stage of disease), and vital status (alive or deceased) determined annually. For deceased cases, the underlying cause of death is also included. The primary site, behavior, grade, and histology of each cancer are coded according to the International Classification of Disease for Oncology, 2nd edition.11 The NJSCR follows the data standards promulgated by the North American Association of Central Cancer Registries (NAACCR), including the use of the Surveillance Epidemiology and End Results (SEER) multiple primary rules.12-16
The NJSCR is a member of NAACCR, an organization that sets standards for cancer registries, facilitates data exchange, and publishes cancer data. The NJSCR also has been a participant of the National Program of Cancer Registries sponsored by the Centers for Disease Control and Prevention since it began in 1994. In 1998, the NJSCR attained the NAACCR Gold Medal for high quality data.
The cancer data contained in this report are from the New Jersey State Cancer Registry (NJSCR), New Jersey Department of Health and Senior Services. For this report, incident cancer cases diagnosed only in the invasive stages are included; the in situ stage cases are excluded. The reason for excluding the in situ cases is that data on cancer incidence for the U.S. and other cancer registries published by the federal government or NAACCR do not include in situ cases or include in situ cases separately from the invasive cases. Following the SEER multiple primary rules, individuals could be counted more than once if they were diagnosed with two or more primary cancers.
Annual population estimates for New Jersey, used to calculate the incidence rates, for the years 1979 through 1995 are from the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) program. Since the population estimates for 1996 are not yet ready, the estimates for 1995 were used for 1996.
In April 1998, NAACCR awarded the NJSCR its gold standard, the highest standard possible, for the quality of the 1995 data. The criteria used to judge the quality of the data were completeness of cancer case ascertainment, completeness of certain information on the cancer cases, percent of death certificate only cases, percent of duplicate cases, passing an editing program, and timeliness. These same quality indicators applied to earlier NJSCR data also have demonstrated a high degree of accuracy and reliability of the data presented in this report. The 1996 data are preliminary.
While our estimates of completeness are very high, some cases of cancer among New Jersey residents who were diagnosed and/or treated in other states may not yet have been reported to us by other state registries. This fact should be considered in interpreting the data for the more recent years. However, these relatively few cases will not significantly affect the cancer rates in these years, or alter the overall trends presented in this report.
Calculation Of Rates
Annual population estimates for New Jersey, used to calculate incidence and mortality rates, for the years 1979 through 1995 are from the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) program. Since the population estimates for 1996 were not yet ready, the estimates for 1995 were used for 1996. All the incidence rates were age-adjusted using the 1970 U.S. Standard Population. This allows comparisons among the rates by year, race, and geographic area. An explanation of why and how the incidence rates were age-adjusted follows.
Cancer occurs at different rates in different age groups, making age a very important risk factor for cancer. Therefore, incidence rates are frequently calculated separately for specific age groups. These rates are referred to as age-specific rates. The age-specific rate for a time period of length t is calculated as follows:
where ra = the age-specific rate for age-group a, na = the number of events (cancer diagnoses, for example) in age-group a during the time period, t = the length of time in years, and Pa = average size of the population in age-group a during time t (mid-year population or average of the mid-year populations).
Multiplying ra by 100,000 expresses the rate as the number of cases per 100,000 persons.
When comparing rates across different population subgroups, e.g. by race, or across different years, it is important to account for differences in age distributions. We calculate an age-adjusted rate using a weighted-average of the age-specific rates. This method of age adjustment is known as direct age-standardization. The age-adjusted rate is obtained by using the age distribution of a standard population as the weights17:
where R = the age-adjusted rate, ra = the age-specific rate for age-group a, and Std.Pa = the number of people in age group a of the standard population.
Multiplying the age-adjusted rate by 100,000 expresses it as the number of cases per 100,000 persons.
The standard population used for age adjustment throughout this report is the 1970 U.S. Standard Population. This is the traditional standard population used in much of the published cancer incidence data.
Counts of fewer than five and their rates are not included in the tables in order to protect confidentiality of the data. For race and gender groups with many counties with many annual counts fewer than five, annual average rates for the combined years 1986-1990 and 1991-1996 were calculated. Also, rates based on low counts are very unstable and may fluctuate greatly from year to year due to chance and other factors. For this reason, rates based on low counts should be interpreted very carefully.