“Just the facts, ma’am” is a catchphrase attributed to detective Joe Friday in the classic television police drama Dragnet. If all science communicators took that message to heart, we would not be exposed to the diarrhea of misinformation that plagues our lives today.

That, though, brings up the question of what is meant by “fact.”

A fact is defined as anything that can be proven to be true. Water is composed of hydrogen and oxygen. That can be proved and is incontestable. However, when it comes to matters of health, facts are harder to come by because absolute proof is elusive.

We cannot point a finger at a smoker and declare that they will be stricken with lung cancer. Because of mountains of published epidemiological evidence, we can say it is a fact that their likelihood of having cancer is greater than if they were a non-smoker. However, when questions such as a prostate-specific antigen (PSA) blood test for prostate cancer arise, the data accumulated by numerous scientific studies does not allow for incontestable facts. The best we can do is rely on experts to interpret the massive amount of data and tease out recommendations that are destined to be qualified by nuances.

The extensive publicity generated by former U.S. president Joe Biden’s prostate cancer diagnosis has led to an eruption of questions about testing for prostate-specific antigen, a protein produced by the prostate gland. Elevated levels in the blood can be caused by various conditions that include a benign enlarged prostate, prostatitis or cancer. Who should be tested and when is the subject of much debate,........

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