Declines in Prostate Cancer Incidence After Changes in Screening Recommendations

David H. Howard, PhD

On August 5, 2008, the US Preventive Services Task Force (USPSTF) recommended against screening men 75 years or older for prostate cancer.1 For men younger than 75 years, the USPSTF maintained its previous recommendation: “ . . . the evidence is insufficient to recommend for or against routine screening for prostate cancer. . . ”2 (p915) (although this recommendation was changed to “do not screen” younger men in the 2011 guidelines). This study evaluates trends in prostate cancer incidence following the release of the 2008 USPSTF recommendation. If the revised recommendation led to a decline in prostate cancer screening rates, there should be a corresponding decline in the incidence of early-stage tumors among men 75 and older relative to trends in the incidence of late-stage tumors and early-stage tumors in younger men.

Methods

I measured trends in prostate cancer incidence rates by age group using the Surveillance, Epidemiology and End Results (SEER) 18 registry data, covering 28% of the US population. The SEER registries collect information on all newly diagnosed cancer cases in their respective catchment areas.

Prostate tumors were identified using International Classification of Diseases for Oncology version 3 code 619. I classified cases by stage at diagnosis using the derived American Joint Committee on Cancer summary stage variable: early (T1 or T2), late (T3 or T4), or unknown. I grouped patients into 3 age categories (30-64 years, 65-74 years, and 75 years and older). I calculated incidence rates per 100 000 persons, standardized within age categories by age (in 5-year age groups), race (white, black, American Indian, or other), and ethnicity (Hispanic or not Hispanic) to the 2009 population. I used an unpaired t test for proportions to assess the significance of differences in rates between years. The data were analyzed in Stata version 11 (StataCorp) statistical software.

Results

The data included 254 184 prostate cancer cases. There were 198 417 early-stage cases, 34 695 late-stage cases, and 21 072 cases of unknown stage. There were 109 053 cases (all stages) among men aged 30 to 64 years, 91 868 cases among men aged 65 to 74 years, and 53 263 cases among men 75 years and older.

The Figure displays the age and race/ethnicity-adjusted incidence rates of early-stage tumors among men aged 65 to 74 years (the upper line) and 75 years and older (the lower line). The trend lines generally mirror each other, but there is a sudden decrease in the incidence of early-stage tumors among men 75 and older after the release of the revised USPSTF recommendation.

Figure. Trends in the incidence of early-stage prostate tumors by age group. Rates are standardized by 5-year age groups and race/ethnicity to the 2009 population. Source: analysis of Surveillance, Epidemiology and End Results (SEER) 18 registry data. USPSTF indicates US Preventive Services Task Force.

Between 2007 and 2009, the adjusted incidence rate for early-stage tumors among men 75 years and older decreased from 443 to 330 per 100 000 (−25.4%; P < .001). The absolute number of cases declined from 8137 to 6162. The incidence of late-stage tumors decreased from 83 to 71 (−14.3%; P < .001), and the incidence of tumors with unknown stage decreased from 124 to 103 (−16.8%; P < .001). The incidence of early-stage tumors among men aged 65 to 74 years decreased from 697 to 591 (−15.2%; P < .001). The incidence of early-stage tumors among men aged 30 to 64 years decreased from 105 to 93 (−11%; P < .001). Incidence trends for all age and stage groups are given in the eTable.

In the past, clinicians and the public have heeded the advice of the United States Preventative Services Task Force (USPSTF) about prostate cancer screening, suggests researchpublished online July 23 in the Archives of Internal Medicine.

After the group’s 2008 guidance, which recommended against screening men older than 75 years, the incidence of early-stage disease in older men plunged 25% in the United States.

“There was an immediate decline in the incidence of early-stage prostate cancer tumors among men 75 years and older after the USPSTF recommended against screening this group,” writes author David Howard, PhD, from the Department of Health Policy and Management at Emory University in Atlanta, Georgia.

Dr. Howard found that from 2007 to 2009, the adjusted incidence rate for early-stage tumors in men 75 years and older decreased from 443 to 330 per 100,000 (−25.4%; P < .001). The absolute number of cases declined from 8137 to 6162.

Dr. Howard used data from the Surveillance, Epidemiology, and End Results (SEER) 18 registry, which collects information on newly diagnosed cancer cases in catchment areas.

He challenges recent results that indicated that there was no change in PSA screening rates from 2005 to 2010 (JAMA. 2012;307:1692-1694). The data source for that study was the National Health Interview Surveys, in which American residents self-report health behaviors and diseases. “Self-reported PSA testing measures have poor sensitivity and specificity,” scolds Dr. Howard.

An immediate question arises from Dr. Howard’s analysis: Will it happen again because of the 2012 USPSTF recommendation against routine testing for all healthy men?

In an unrelated essay (J Clin Oncol. 2012;30:2581-2584), a group of experts assert that the answer is no.

The USPSTF’s “blanket rejection” of the PSA test is “unlikely to influence practice,” according to Sigrid Carlsson, MD, PhD, from the Memorial-Sloan Kettering Cancer Center in New York City and Göteborg University in Sweden, and colleagues. Dr. Carlsson and her fellow experts wrote an essay criticizing the new USPSTF guideline for a number of “very important errors,” as reported by Medscape Medical News.

“PSA testing is not likely to go away,” wrote Dr. Carlsson and coauthors.

Dr. Howard voiced similar thoughts in an email to Medscape Medical News.

“Physicians are probably more willing to discontinue screening older patients. There might be more resistance to discontinuing screening among younger, healthier men,” he said.

But Dr. Howard also said: “I think it will have an impact. There is growing publicity about the problem of ‘overdiagnosis’, which might make physicians and some patients more receptive to the USPSTF recommendation.”

The recently published PIVOT study might also contribute to the way the new guidance is received, noted Dr. Howard. This major randomized controlled trial found that prostatectomy did not improve survival significantly, compared with observation, in men with localized disease. “This research also casts doubt on the benefits of early detection, which may amplify the impact of the USPSTF recommendation,” said Dr. Howard about PIVOT.

Nonetheless, “many men will continue to receive regular PSA tests,” he added.

More Details

In addition to finding that the rate of early-stage prostate cancers dropped among older men after the 2008 recommendation, Dr. Howard found that other indicators of PSA testing also dropped.

The incidence of late-stage tumors decreased by 14.3% (P < .001), and the incidence of tumors of unknown stage decreased by 16.8% (P < .001). The incidence of early-stage tumors in men 65 to 74 years decreased by 15.2% (P < .001); in men 30 to 64 years, the incidence decreased by 11% (P < .001).

Overall, Dr. Howard found that 254,184 prostate cancer cases were newly diagnosed during the study period. There were 198,417 early-stage cases, 34,695 late-stage cases, and 21,072 cases of unknown stage. There were 109,053 cases (all stages) in men 30 to 64 years of age, 91,868 cases in men 65 to 74 years, and 53,263 cases in men 75 years and older.

7 Responses

Fifteen years ago, a colleague commented that it looks like at the rate biopsies were done, they were going to run out of tumor to take. In a study with Marguerite M Pinto, we reviewed all the the prostate cancers for a full year. Despite the established disease related decision point established by Stamey and associates at Stanford, we found that the probability of a cancer dropped below 10, and had to be weighted against benign prostatic hyperplasia. The probability of carcinoma rose substantially above 10, but there was a substantial amount of noise from BPH. When the PSA level rose to 24 mg/dl (240 mg/L), this was a critical defining value for metastatic disease. In another study with Gustave Davis, the question was whether we could classify the patient probable outcomes using both PSA and Gleason score. Having both values and using Jay Magidson’s graphical ordinal regression program, we could do that. In the following 3 years, Dr. Stamey presented at the American Association for Clinical Chemistry, with devastatingly disappointing news. It was uncanny when he showed metastatic disease above 24, and on the promise unfulfilled. There is another chapter that will unfold beyond the current discussion.

It will be published in Clinical Biochemistry (Elsevier).
Robustness of ProsVue™ linear slope for prognostic identification of patients at reduced risk for prostate cancer recurrence: Simulation studies on effects of analytical imprecision and sampling time variation

Analytical imprecision related to expected PSA values in a stable disease population results in ≤1.2% misclassifications. For recurrent populations, an analysis taking into account correlation between sampling time points demonstrates that classification switching across the 2.0 pg/ml/month
cutoff occurs at a rate ≤11%. In the narrow region of overlap between populations, classification switching maximizes at 12.3%. Lastly, sampling time variation across a wide range of scenarios results in 99.7% retention of proper classification for stable disease patients with linear slopes up to the 75th
percentile of the distribution.