A study (Partin, et al) of 737 men undergoing prostate biopsy found 40% had prostate cancer. For men whose tPSA was between 2 to 6 ng/ml, cutoff values for tPSA at 2.5 ng/ml and cPSA at 2.2 ng/ml successfully detected 95% of cancer cases (i.e., 95% sensitivity). However, the "specificity" -- the percent of true negatives identified by the test (or percent of false positives avoided by the test) -- cPSA was 67% more specific than tPSA (19.6% vs. 11.7%).(1)

Given recent studies on the incidence of prostate cancer in men with PSA values in the 2.5 to 4 ng/ml range, researchers are evaluating if the current cut-off value of 4 ng/ml should be lowered. In a study by Barstch, et al, of 191 men with tPSA values between 2 to 4 ng/ml, 29% were diagnosed with prostate cancer. Cutoff values for tPSA at 2.5 ng/ml and cPSA at 2.2 ng/ml successfully detected 86% of prostate cancer cases (i.e., 86% sensitivity); however, cPSA was 68% more specific than tPSA (34.6% vs. 20.6%).(2)

"The value of cPSA is that it can decrease the number of unnecessary prostate cancer biopsies," said Herbert Lepor, M.D., Professor and Chairman, New York University School of Medicine. "Since cPSA costs the same as standard tests, and provides better results, physicians should consider using cPSA when screening for prostate cancer."

Conventional PSA testing measures tPSA. The Bayer Diagnostic cPSA test, approved by the U.S. Food and Drug Administration in September 2000, measures the level of cPSA (PSA bound to other proteins).

Additional Findings Presented: cPSA Had More Predictive Power

A study presented by Stacy Childs, M.D., examined the power of cPSA, tPSA, digital rectal exam (DRE), age and total prostate volume to detect prostate cancer.(3) Compared to tPSA values, cPSA had more predictive power, while cPSA plus suspicious DRE findings had the highest predictive value. The findings suggest that cPSA levels together with other patient factors such as age and prostate size can help physicians better predict prostate cancer risk and the need for a biopsy.

Cost Benefit of cPSA Testing

Lars Ellison, M.D., presented results from a cost-benefit analysis of different PSA tests and resulting biopsies to determine which test was the most appropriate for population-based screening.(4) The study concluded that the use of cPSA, with 3.8 ng/ml positive threshold, was the most-effective screening approach because it had a strong cost-benefit ratio.

Prostate Specific Antigen

PSA is a glycoprotein produced almost exclusively by epithelial cells in the prostate. Serum PSA has proven to be an extremely useful marker for early detection of prostate cancer and in monitoring patients for disease progression and the effects of treatment. PSA serum levels of 4.0 ng/ml or less are usually considered normal; higher levels (4 to 10 ng/ml or higher) are often found in men with prostate cancer. However, current PSA testing generates up to 60% "false positives" because PSA levels can also increase due to enlargement of the prostate, a non-cancerous condition increasingly common as men get older; acute infections of the prostate (prostatitis); transurethral prostatectomy; and other factors. On the other hand, testing can also generate "false negatives" because a significant number of cases of prostate cancer have been found in men whose PSA was "normal," between 2.5 to 4 ng/ml.(5) As a result, much research has focused on ways to improve the accuracy of PSA testing, i.e., to reduce false negatives (making it more sensitive) and false positives (making it more specific). Data presented at the AUA shows that the cPSA test overcomes many of the shortcomings of PSA and offers physicians and patients a strong weapon in the fight against prostate cancer.

Prostate Cancer

Prostate cancer is currently the most prevalent form of cancer in men and the second leading cause of male cancer death in the U.S. The American Cancer Society estimates that 189,000 men will be diagnosed with prostate cancer this year in the U.S., with 30,200 deaths attributable to prostate cancer.

Bayer Diagnostics

With approximately 7,000 employees worldwide and 2001 sales of $1.8 billion, Bayer Diagnostics (http://www.bayerdiag.com), based in Tarrytown, New York, USA, is one of the largest diagnostic businesses in the world. The organization supports customers in 100 countries through an extensive portfolio of central laboratory, self-testing, nucleic acid and near patient care diagnostics systems and services for use in the assessment and management of health, including the areas of cardiovascular and kidney disease, oncology, virology, women's health and diabetes. Bayer Diagnostics is a part of the worldwide Bayer Group, a $29 billion international health care and chemicals group based in Leverkusen, Germany. Bayer Diagnostics' global headquarters in the United States operates as part of Bayer Corporation of Pittsburgh, a research-based company with major businesses in health care, life sciences and chemicals.

This news release contains forward-looking statements based on current assumptions and forecasts made by Bayer Group management. Various known and unknown risks, uncertainties and other factors could lead to material differences between the actual future results, financial situation, development or performance of the company and the estimates given here. These factors include those discussed in our public reports filed with the Frankfurt Stock Exchange and with the U.S. Securities and Exchange Commission (including our Form 20-F). The company assumes no liability whatsoever to update these forward-looking statements or to conform them to future events or developments.

(1) Cheli CD, Bartsch G, Hominger W, Babaian RJ, Fritsche HA, Taneja S, Lepor H, Childs S, Stamey T, Sokoll LK, Chan DW, Brawer MK, Partin AW. Final results of a multicenter prospective evaluation of complexed PSA for early detection of prostate cancer. Presented at: American Urological Association annual meeting, Orlando, Florida, May 25, 2002. Abstract ID 834 (2) Bartsch G, Cheli CD, Hominger W, Babaian RJ, Fritsche HA, Lepor H, Taneja S, Childs S, Stamey T, Sokoll LK, Chan D, Brawer MK, Partin A. Complexed PSA for early detection of prostate cancer in men with serum PSA levels of 2-4 ng/mL. Presented at: American Urological Association annual meeting, Orlando, Florida, May 25, 2002. Abstract ID 838 (3) Childs S, Lugg J, Thiel RP, Cheli CD, Brawer MK, Bartsch G, Babaian RJ, Fritsche HA, Taneja S, Lepor H, Stamey T, Sokoll LK, Chan DW, Partin AW. Decision tree algorithms for prostate cancer detection: complexed PSA and other significant predictors using CHAOD analysis. Presented at: American Urological Association annual meeting, Orlando, Florida, May 25, 2002. Abstract ID 1286 (4) Elison L, Veltri R, Cheli CD, Partin AW. Cost-benefit analysis of total PSA, free/total PSA and complexed PSA for prostate cancer screening. Presented at: American Urological Association annual meeting, Orlando, Florida, May 25, 2002. Abstract ID 46 (5) Catalona WJ, Smith DS, Ornstein DK. Prostate cancer detection in men with serum PSA concentrations of 2.6 to 4.0 ng/mL and benign prostate examination. Enhancement of specificity with free PSA measurements. JAMA. 1997 May 14; 277(18):1452-5.

DATA CORRESPOND TO ABSTRACTS #46, 834, 838, 1286.