PSA detects clinically important cancers in older men

Orlando, FL-More than half of prostate cancers detected by PSA measurement are intermediate or high risk at diagnosis, according to findings from a large, population-based study.

In addition, men older than 75 years of age account for approximately 40% of the high-risk, PSA-detected cancers and have almost 10 times the likelihood of having high-risk disease compared with men younger than 50 years of age.

Older age and African-American race were the risk factors discovered for presenting with intermediate- or high-risk disease. The findings represent the first indication that a significant number of elderly men and African-Americans may have an aggressive form of prostate cancer, said first author Hong Zhang, MD, PhD, who presented the data at the Genitourinary Cancers Symposium in Orlando, FL.

Some 70,345 men identified with American Joint Committee on Cancer stage T1cN0M0 disease from the Surveillance, Epidemiology, and End Results (SEER) database and who were diagnosed between 2004 and 2008 formed the study population. Multivariate logistic regression was conducted to model the probability of developing low-risk (PSA <10.0 ng/mL and Gleason score ≤6), intermediate-risk (PSA from 10.0 to 20 ng/mL and/or Gleason score 7), and high-risk disease (PSA >20.0 ng/mL and/or Gleason score ≥8).

Among the study participants, 47.6% had low-risk disease, 35.9% had intermediate-risk disease, and 16.5% had high-risk disease. Men with high-risk disease were significantly older (mean age, 72 years) than those with intermediate- and low-risk disease (mean ages, 70 and 67 years, respectively; p<.01). Men with high-risk disease were also significantly more likely (p<.01) to be African-American. Some 17.7% of the men with high-risk disease were African-American compared with 16.3% of those with intermediate-risk disease and 13.1% of those with low-risk disease.

While accounting for 40% of all patients with high-risk disease, patients 75 years of age and older had a 4.47-fold higher probability of developing intermediate-risk disease (p<.01) and 9.4-fold higher probability of developing high-risk disease (p<.01) compared with patients younger than 50 years of age. African-Americans of all ages had a 1.8-fold higher likelihood of developing high-risk disease compared with Caucasian men.

The potential benefit of PSA screening in men older than 75 years of age and African-American men requires further investigation, said Dr. Zhang, associate professor of radiation oncology at the University of Rochester Medical Center, Rochester, NY.

91% survival rate for low-risk disease

Average 10-year survival rates are 91% for low-risk, 84% for intermediate-risk, and 80% for high-risk disease. These risk levels are defined based on clinical stage, PSA level, and Gleason score.

Commenting on the study, Bruce J. Roth, MD, professor of medicine at Washington University, St. Louis, said, “Certainly, the concept that older patients, however defined, would all have indolent prostate cancer and they’re all destined to die of something else may not necessarily be true. We see a significant percentage of people with intermediate- and high-risk disease in that patient population.

“What it ultimately means is that a numeric age is not a great determinant of who should and who should not receive PSA screening,” added Dr. Roth, who moderated a media presentation of the study.

Leonard G. Gomella, MD, remarked that over-detection or over-screening for prostate cancer is not the overriding issue, but rather overtreatment is.

“The problem isn’t really a screening problem but about over-treating patients who have clinically unimportant prostate cancer. This is certainly true of the older population, who may have clinically important cancer that warrants treatment,” said Dr. Gomella, chair of urology and associate director of clinical affairs at Jefferson Kimmel Cancer Center, Thomas Jefferson University, Philadelphia. Dr. Gomella serves on the American Society of Clinical Oncology media committee and was not involved with the study.

Making absolute recommendations for screening without considering individual factors “is probably not fair to the patient or society,” added Dr. Gomella, who suggests considering a patient’s comorbidities when making a decision about screening.

The Genitourinary Cancers Symposium was jointly sponsored by the American Society of Clinical Oncology, American Society for Radiation Oncology, and Society of Urologic Oncology.UT