Introduction

This report examines prostate cancer incidence and mortality in New Jersey, for the years 1979-1996, and presents data on stage at diagnosis, which is an important factor in survival of patients with this disease. It also compares New Jersey with the United States for these years. (Please see the Glossary for definitions of incidence and mortality as well as other terms used in this report).

The report was based on data that had been received and undergone quality assurance as of the summer of 1999. As the report was being prepared, preliminary data for 1997 became available and were included. During the early part of 2000, incidence data for 1997 and several years prior will be published and may differ slightly from the numbers and rates in this report because the New Jersey State Cancer Registry is constantly being updated with previously missing data.

General Information on Prostate Cancer

Prostate cancer is the most common cancer among men (excluding skin cancer) and the second leading cause of cancer deaths in men. The risk of prostate cancer increases greatly with age. The average age at diagnosis is 72 and 80 percent of the cases are diagnosed in men over 65. The incidence of prostate cancer is substantially higher in black men than in white men. A family history of prostate cancer has been shown to increase the risk of developing the disease. A number of suspected risk factors have and are being studied, including high fat consumption, high levels of male hormones, smoking, and alcohol consumption, but thus far scientists have linked none of these factors definitively as causes of this disease.

Almost all men over age 30 have microscopic cancerous changes in cells of the prostate, but only about 10 percent of these men ever go on to develop symptomatic prostate cancer. Research is currently ongoing to understand how and why this transformation takes place and how it can be prevented. Many prostate cancers are extremely slow-growing and may not ever progress to life-threatening illness.

Prostate Cancer Incidence Among New Jersey Men

The annual incidence of invasive prostate cancer in New Jersey rose gradually from about 2,500 cases in 1979 to 3,500 in 1988. The number of new cases per year then rose rapidly to a peak of almost 8,000 cases in 1992 and then declined. Similarly, the annual age-adjusted incidence rate (new cases per 100,000 men) peaked in 1992 at 194.2 and then declined. The incidence rate for black men peaked in 1993 at 247.2 while the incidence rate for white men peaked in 1992 at 184.7. Preliminary prostate cancer incidence data for 1997 show age-adjusted incidence rates per 100,000 men to be about 155 overall, approximately 145 for white men, and 225 for black men.

Between 1984 and 1996, (the years for which stage data were most complete) the annual
proportion of cases diagnosed in the early stages of the disease (either in-situ or localized)
increased from about 55 percent in 1984 to about 67 percent in 1996. However, black men had a
lower percentage of their prostate cancers diagnosed at these early stages than did white men. All
of the above New Jersey patterns mirrored those of the nation as a whole.

More widespread use of screening methods such as the prostate specific antigen (PSA) test and the digital rectal examination (DRE) which identify prostate cancer in the early stages explains at least part of the increase in prostate cancer incidence rates among New Jersey men between 1979 and 1996. The drop in the incidence rates after 1992 is probably due in part to screening and early diagnosis of some men in preceeding years who otherwise would have been diagnosed at a later date with later stage disease. Such patterns of increase and then decrease in incidence rates is typical after widespread introduction of a new screening method.

Prostate Cancer Mortality Among New Jersey Men

Deaths due to prostate cancer increased from 744 in 1979 to 1,201 in 1993 and then declined slightly. The annual age-adjusted mortality rate (deaths per 100,000 men) also rose from 22.7 in 1979 to and 29.0 in 1993, but has been declining in New Jersey in years since, similar to the U.S. trend. During the entire period of 1979 through 1996, the prostate cancer mortality rate for black men was more than double that of white men.

The decline in prostate cancer deaths may be due to more men being screened using screening methods that identify prostate cancer early. Survival rates for men with prostate cancer diagnosed in the early stages are much greater than those for men diagnosed in the later stages of the disease.

Differences Between White and Black Men

The reasons for black men's higher incidence rates are not well understood. The higher mortality rates among black men reflect their higher incidence rates and may also be explained in part by the higher percentage of prostate cancers diagnosed at later stages.

Prostate Screening Among New Jersey Men

Prostate cancer screening has become much more common in the past 10 years. There are two types of screening tests which are widely performed:

    (1) The PSA test is a blood test which measures the level of prostate specific antigen. The
current level which is used to indicate possible prostate cancer is a PSA concentration greater than 4.0 nanograms per milliliter (ng/ml).

    (2) A physician may perform a digital rectal exam (DRE) to assess whether the prostate is
enlarged, or contains a nodule(s), which can be an indication of prostate cancer. As a follow-up to an abnormal DRE, a transrectal ultrasound (TRUS) imaging test is sometimes recommended.

Prostate Cancer in New Jersey Compared with the U.S.

Prostate cancer rates in New Jersey have closely followed the pattern for the United States. Since 1979, New Jersey and total U.S. incidence rates rose from about 76 per 100,000 to almost 200 per 100,000 in 1992. Incidence rates in New Jersey and the U.S. have declined since that time. Whereas New Jersey incidence rates were somewhat lower than the national average for most of those years, the New Jersey rates were slightly higher than the U.S. rates in 1995 and 1996, which may represent improved reporting of non-hospitalized cases.

Conclusions

Prostate cancer incidence has recently declined in New Jersey and in the U.S. after a peak in 1992. Black men are more likely than white men to get prostate cancer. They are also more likely to be diagnosed at a later stage, and are more likely to die of the disease. Additional research is needed on the causes of prostate cancer and methods of preventing it. At this time, early detection and treatment are the best methods to reduce mortality due to prostate cancer.