Prostate Cancer In New Jersey 1979-1996
Technical Notes

The New Jersey State Cancer Registry

The goals of the New Jersey State Cancer Registry (NJSCR) are to:

  • monitor cancer trends in New Jersey;
  • promote scientific research;
  • respond to New Jersey residents about cancer concerns;
  • educate the public;
  • provide information for planning and evaluating cancer prevention and control activities; and
  • share and compare cancer data with other states and the nation.

The New Jersey State Cancer Registry (NJSCR) is a population-based incidence registry that serves the entire state of New Jersey, with a population of approximately 8 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 in facilities outside the state can be identified.

All primary invasive and in situ neoplasms, except certain carcinomas of the skin and in situ cervical cancer 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 (WHO, 1990). 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.

The NJSCR is a member of NAACCR, an organization which sets standards for central 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 and 1999, the NJSCR attained the NAACCR Gold Standard for high quality data.

The New Jersey Department of Health and Senior Services has participated in several studies of prostate cancer among men including a previous investigation of prostate cancer risk factors among black men. At the present time, the Department is collaborating with epidemiologists at the Robert Wood Johnson Medical School to determine whether PSA screening has prevented death from prostate cancer. That study will make an important contribution to the national recommendations and practices regarding the optimal use of PSA screening. In addition, the Cancer Epidemiology Service is engaged in a special project funded by the federal CDC to use its new Geographic Information System technology together with the NJSCR to define areas where outreach to black men is needed in order to decrease the proportion of prostate cancers which are diagnosed at later stages of the disease.

Data Sources

The prostate cancer data contained in this report are derived from three sources:

  • New Jersey prostate cancer incidence (1979-1996) - New Jersey State Cancer Registry (NJSCR), New Jersey Department of Health and Senior Services;
  • New Jersey prostate cancer mortality (1979-1996) - Vital Statistics, New Jersey Department of Health and Senior Services;
  • U.S. prostate cancer incidence rates and mortality rates (1979-1996) - Surveillance, Epidemiology and End Results (SEER), National Cancer Institute.

The data in this report are current as of the summer of 1999. Any updates performed later were not adjusted for in the calculations. For this report, incident prostate cancer cases diagnosed only in the invasive stages are included; the in situ stage cases are excluded, except for the section on the stage at diagnosis which includes the in situ cases (Tables 2, 7-9 and Figures 7-9). The reason for excluding the in situ cases for most of the report is that data on prostate cancer incidence for the U.S. and other cancer registries published by the federal government or other national organizations do not include in situ cases, or they report in situ cases separately from the invasive cases. In 1995, the SEER coding rules were changed such that more than one primary prostate cancer could no longer be designated in one individual. The number of such cases in the NJSCR are too few to perceptibly change the rates or trends in this report.

The most recent data from SEER were used to compare New Jersey prostate cancer incidence and mortality with the United States. The incidence data for the United States are based on eleven population-based cancer registries.

Data Quality

In April 1998 and April 1999, NAACCR awarded the NJSCR the Gold Standard, its highest award, for the quality of the 1995 and 1996 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. While our estimates of completeness are very high, some cases of prostate cancer among New Jersey men who were diagnosed and/or treated in other states, may not yet have been reported to us by other state registries. 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 1996, are from the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) program. All the incidence and mortality rates, except age-specific 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 and mortality 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 and mortality 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 or deaths, 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 weights

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.


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