Prostate Cancer Screening: What We Know, Don't Know, and Believe

Prostate Cancer Screening: What We Know, Don't Know, and Believe

Overdiagnosis makes screening seem to save lives when it truly does not (6). Cases of overdiagnosed cancer fulfill histologic criteria for cancer, but are not destined to progress and kill within the patient's natural lifetime. Yet, when detected through screening, these tumors are commonly treated, exposing patients to the harms of treatment without any true associated benefit. The man with such a cancer often believes that screening and treatment saved his life, but he would have been just fine had the cancer never been detected and treated. Overdiagnosis also increases the proportion of patients surviving 5 and 10 years. Lead-time bias increases apparent survival rates. Because screening diagnoses some patients earlier, they live longer after cancer diagnosis, even though they do not live longer than counterparts with similar cases of cancer that were not screen-detected. Overdiagnosis was known to be an issue in prostate cancer well before screening became popular. In the 1980s, the respected prostate cancer expert, Dr. Willet Whitmore, said that the quandary in prostate cancer is, “If cure is necessary, is it possible, and if cure is possible, is it necessary (7)?”

The screening literature stresses a difference between mass screening, in which large numbers of men are tested at an event, and screening within the physician–patient relationship. Much of my own concern about prostate cancer screening has been with mass screenings that mislead men to believe that screening can only help them. Over the past 20 years, celebrities, athletes, politicians, and prostate cancer survivor groups have endorsed screening. Mass screening is commonly conducted in shopping malls, churches, and community centers; at conventions and state fairs; and even in vans parked in grocery store parking lots. Hospitals, medical practices, fraternities, politicians, radio stations, television channels, and even an adult diaper manufacturer have sponsored mass prostate cancer screenings. Promotions for these events frequently discuss the high proportion of men with screen-detected tumors surviving 5 years and sometimes claim that screening saves lives. They never mention the potential harms of screening. Many well-meaning persons have supported screening activities and chose not to listen or believe those who have urged caution about screening. Mass screening is also a lucrative business. As Upton Sinclair once said, “It is difficult to get a man to understand something, when his salary depends on his not understanding it (8).”

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