The death rate from prostate cancer is at an all-time low for both white and black Americans — and a new study suggests that a primary reason may be increased use of the PSA blood test (prostate specific antigen test) to find prostate cancer early.

However, study author Kenneth C. Chu, PhD, of the Center to Reduce Cancer Health Disparities warned men to talk with their doctors about the pros and cons of being tested. The drop in death rates comes "at the cost of a very large increase in the number of men treated for prostate cancer since 1986," wrote Chu and colleagues in the journal Cancer (Volume 97, Issue 6, 2003: 1507-1516).

Treatments can cause serious side effects and many prostate cancers may grow so slowly they would never cause health problems if left untreated.

The researchers looked at trends in both newly diagnosed cases of prostate cancer (incidence) and deaths from prostate cancer (mortality) — then analyzed the trends further by disease stage. Study data covered from 1969 to 1999 and came in part from the National Cancer Institute’s large national cancer survey program, Surveillance, Epidemiology, and End Results (SEER), which collects data from nine population-based US cancer registries.

Prostate cancer incidence rates rose from 1986 -- when the PSA test was approved -- through 1991, with African-American trends mirroring rates for white men a year or so later. Then after 1991, death rates for white and black men began to drop sharply.

In 1995, the prostate cancer death rate for white men age 50-84 years dropped below what it was in 1986, the year the PSA test was approved. The rate for black men in the same age group passed that mark in 1997. Death rates continue to decline, which means more men now survive prostate cancer.

"Mortality rates (in 1998-99) are the lowest since 1950 in white men," said Chu. And among black men, death rates in 1999 were "the lowest since 1969 when those rates were first recorded," Chu explained. The record low rate for black men was seen in men age 50-69 years.

The drop in death rates for local, regional, and advanced cancers combined was due to fewer men dying from advanced prostate cancer, according to the new study. But medical treatments didn't save any more men with advanced cancer -- instead fewer men were diagnosed with advanced ("distant") disease. Chu and colleagues say the PSA test was finding prostate cancer in earlier stages, when treatments are more successful.

"The PSA test is causing stage shifts from distant (advanced) disease to more treatable stages of the disease," explained Chu.

It's unlikely that the new report will settle the controversy about whether the PSA test really helps to save lives. American Cancer Society director of prostate and colorectal cancer, Durado Brooks, MD, said the report "is not ground-breaking, but it is important." The findings need to be confirmed by other studies, and it may be several years before that happens.

Use of the PSA test in other countries has shown mixed results so far. For example, in the United Kingdom prostate cancer death rates have dropped recently, as they have in the US. But there has been no large screening program and there was no large increase in incidence, as seen in the late 1980s in the US.

Until more research provides a definitive answer about the value of PSA testing, both Brooks and Chu said men should follow American Cancer Society guidelines on testing for prostate cancer. Men need to know the benefits and the limitations of the PSA test and the medical procedures that may follow, in order to make an informed decision about whether to be tested.

"This does not alter American Cancer Society recommendations that men talk to their doctors about the advantages and risks of being screened for prostate cancer," said Brooks.

ACS advises men talk to their doctors beginning at age 50, or at age 45 for African-American men, and/or earlier if there's a strong family history of the disease.

Chu insists that, "The declines in mortality are big and they're real." He says credit is due to the American Cancer Society for the fact that fewer men are dying from prostate cancer…and for helping more people survive breast and colon cancer as well.

"It's a tribute to the American Cancer Society that their recommendations for prostate cancer screening, and breast and colon cancer screening, are causing the declines in mortality rates seen in the 1990s."