I have had a dozen surgical procedures in my life. Some have gone well. Some I prefer not to talk about.

I did some smart things before each procedure: I pursued every viable nonoperative treatment; I got opinions from multiple physicians about whether I am likely to benefit from the procedure; and I sought out surgeons at elite institutions.

But I never asked a question I now realize all patients should ask before letting a surgeon slice into their bodies: “How many of these procedures did you do last year?”

There are a lot of factors that influence surgical success. It starts with the health of the patient – the sicker you are, the greater risk you have of experiencing postoperative problems. In addition, it’s critical to figure out whether surgery is “indicated,” as clinical folks would say it. That is, even if it goes well, will surgery make you better off. If you don’t need surgery in the first place, then it doesn’t matter if you have the best surgeon in the world.

But once you have decided surgery is the way to go, you are best served by a surgeon, and a hospital, where the procedure is relatively common. All else equal, a surgeon who performs the procedure 10 times a year will not perform it as well is one who does it 40 times.

For example, consider a recent study that evaluated outcomes of patients receiving surgery to treat cancer. Suppose you are unfortunate enough to have pancreatic cancer. If your surgeon performs 10 procedures a year for people with pancreatic cancer, you can expect a 3% chance of dying within 30 days of the procedure. By contrast, if your surgeon performs 100 such procedures a year, that risk will be cut in half. For pancreatic cancer procedures, you are going to want someone who performs at least 40 such operations a year; anything less than that, and you will face an elevated risk of premature death.

For liver cancer, patients whose surgeons performed 10 such procedures a year experience 4% risk of 30 day mortality, a number also cut in half if their surgeon performs at least 40 such procedures.

The number of procedures a surgeon needs to perform each year to maximize their abilities likely varies across procedures. The more complex the intervention, the more experience I’d like my surgical team to have.

If you are about to undergo a risky operation, ask your surgeon how frequently they perform that procedure. And if the answer makes you feel unsure, get a second opinion from another (maybe more experienced?) surgeon.

It might feel presumptuous to ask such a direct question, but doing so could save your life.