Early detection of cancer saves lives — but may do harm

I’ve been meaning to find time to run an excerpt from the forthcoming updated edition of Siddhartha Mukherjee’s Pulitzer Prize-winning book “The Emperor of All Maladies: A Biography of Cancer” that ran last month in The New Yorker.

There’s a “central flaw in our current model of cancer screening,” Mukherjee says. 

Early-stage tumors “might be the kind of early cancers that surgery can cure. They might be slow-growing and unlikely to cause harm. Or, most concerning, they might already have metastasized, rendering local intervention moot. Three possibilities — yet we often cannot tell which we’re confronting,” he says.

And “to complicate matters further, false positives abound: tests that suggest cancer where none exists, leading to unnecessary procedures, anxiety, and harm.”

“In 2021, according to one estimate, the United States spent more than forty billion dollars on cancer screening,” Mukherjee says. On average, a year’s worth of screenings yields nine million positive results — of which 8.8 million are false. Millions endure follow-up scans, biopsies, and anxiety so that just over two hundred thousand true positives can be found, of which an even smaller fraction can be cured by local treatment, like excision. The rest is noise mistaken for signal, harm mistaken for help.”

On top of that, the effectiveness of screening varies dramatically by cancer type, Mukherjee says.

It’s possible that the accelerating forces of cancer genetics and machine learning may transform the landscape of early detection, he says. Perhaps, in time, we’ll build tools that can not only detect cancer’s presence but predict its course.

Meanwhile, what to do? 

Well, for example, the CDC website has an item titled “Should I Get Screened for Prostate Cancer?” It’s intended to help men decide whether to be screened based on their personal risk factors and how they value the potential benefits and harms of screening, diagnosis and treatment.

What about the concern that our federal government’s health care guidance may be less reliable at the moment?

Personally, I like to check what the Mayo Clinic and Cleveland Clinic have to say, along with the government websites of Canada, Australia and New Zealand.