Prostate Cancer: Screening and Early Detection

Michael S. Cookson, MD, Department of Urologic Surgery, Vanderbilt University Medical Center, Nashville, TN

Cancer Control. 2001;8(2) 

In This Article

Screening Controversies

Few topics in prostate cancer are more controversial than the issue of screening. One of the problems within this area is the balance of economic forces and scientific rationale vs the application of health care policy to an individual patient at risk for developing and perhaps dying of his disease. This battle is waged in the background of a cancer with a prolonged doubling time that may requires as long as a decade to elapse before demonstrating what impact (if any) a new treatment may have on the natural history of the disease. Most patients and family members are unwilling to leave their fate to chance. Additionally, it is well known that relying on detection of prostate cancer only after the development of symptoms has historically resulted in the detection of advanced and often incurable cancers.

Certain criteria are thought to be essential for mass screening to be widely accepted by health care policy makers. First, the disease must be common or serious enough to warrant screening. As the most common cancer in men and the second leading cause of cancer deaths, prostate cancer certainly meets this criterion. Second, a test must be available to detect the disease at an early, presymptomatic stage. Studies employing PSA and DRE have again supported this. Third, there must be supporting evidence that treatment of the disease after early detection will result in a reduction in disease morbidity and/or mortality. It is on this final point of contention that the strongest argument against screening exists, and until there is proven benefit to the treatment of these early detection cancers, controversy will continue regarding screening for prostate cancer.

To add support to the argument that screening does not save lives, critics have introduced concerns regarding not only the possibility of overdetection, but also length-time and lead-time bias (Figs 1-2).[23] Lead-time bias suggests that the natural history of the disease is not truly affected by screening. For example, a patient may be diagnosed with prostate cancer at 50 years of age through PSA-based screening. He then undergoes treatment but ultimately progresses and dies at 60 years of age. Accordingly, the same patient without screening develops symptomatic bony metastases at age 58, under-goes treatment with androgen deprivation therapy, and dies at age 60. Thus, in this theoretical scenario, even though he was diagnosed 8 years prior through screening, his death was not affected by screening or early detection. Length-time bias is slightly different but also suggests no benefit to screening. Length-time bias suggests that annual screening is more likely to detect slow-growing tumors, while fast-growing and potentially lethal tumors are less likely to be detected. Thus, it is argued that screening for prostate cancer does not detect the very tumors for which it is intended.

. Lead-time bias suggests that the natural history of the disease is not truly affected by screening. Printed with permission from Medical Education Collaborative, Golden, Colo.

. Length-time bias suggests that annual screening is more likely to detect slow-growing tumors, while fast-growing and potentially lethal tumors are less likely to be detected. Printed with permission from Medical Education Collaborative, Golden, Colo.

Another concern involves the cost of screening. While a full discussion of the economics of prostate cancer screening is beyond the scope of this article, certain points should be considered. First, cost includes not only the cost of detection but also treatment and treatment-related complications. Furthermore, cost can be measured in terms of number of lives saved, life years saved and quality-adjusted life years (QALY). A 1990 report estimated that the cost of screening could be as high as $25 billion annually if all men 50 to 70 years of age in the United States participated in screening.[24] However, these same authors demonstrated that the cost using values of quality-adjusted life-years (QALY) gained through screening is actually better than the cost-benefit ratios of screening mammography for women under the age of 50 and better than some forms of medical treatment for hypertension. Therefore, it could be argued that when considering all the costs of screening and particularly QALY gained, prostate cancer screening is justifiable.

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