The deaths of no fewer than 25 NBA players (and other famous basketball pros) in 2015 set off alarms and made it an infamous year with the most deaths of former players.

That fateful year saw the deaths of Moses Malone, Dolph Schayes, Daryl Dawkins, Rod “Hot Rod” Hundley, Earl Lloyd, Roy Tarpley, Anthony Mason, Jerome Kersey, Harry Gallatin, Mel Daniels, Christian Welp, John “Hot Rod” Williams and the two most-well known Harlem Globetrotters Meadowlark Lemon and Marques Haynes. That’s not to mention the deaths of Hall of Fame coaches Dean Smith and Flip Saunders.

And it wasn’t just deaths due to natural causes, many of the deaths that year shined a spotlight on the potential physical problems that former professional basketball players, particularly front court players, faced after their careers came to a close. In 2015, retired players Malone, Dawkins, Mason, Kersey, Welp and Jack Haley all died early from heart attacks, heart-related disease or problems. What’s worse was that Mason, Haley and Welp all died within three weeks.

NBA Players that Died Early

As reported in a 2011 survey, the average lifespan of an American male was 76 years old while the average lifespan of an African-American male, whom make up the majority of NBA players, was 71.8 years according to another survey. All of the NBA players that passed away before the age of 70 are considered to have died prematurely. With the focus on the premature deaths of NBA players after their careers ended, we wanted to look at a list of NBA players that died “early” or for the purpose of this post, before the age of 60.

NBA Players That Died Early (Ages 21-30)

We’ll start out by looking at the NBA players that died really young; specifically those that passed between the ages of 21-30. In this age range, the majority of players died from an external factor such as a car accident. Still, three players, Fab Melo, Reggie Lewis and Jason Collier, died from heart conditions. As we move through this piece, you’ll see how heart problems as the cause of death becomes more problematic as players age.

Former NBA Players That Died Early(Ages 31-40)

It’s not a huge sample size, but nearly half of the 11 players in this age range died of a heart attack while Bison Dele and Lorenzen Wright passed away from mysterious circumstances.

NBA Players That Died Prematurely (Ages 41-50)

From ages 41-50, the following list is made up entirely of retired or inactive players. As professional athletes begin their lives after their athletic careers, their metabolisms slow due to more-leisurely lifestyles. Waistlines and bellies grow. Players that used to be physical specimens begin to really age in this decade of life. As a result, deaths are more health-related than freak accidents. In this group of players, approximately 3/4ths of the players passed from cancer, heart attacks and other diseases.

Retired Players That Died From 51-60 Years Old

In the 51-60 age group, former players health complications are dominated by cancer and heart-related complications. On this list of players, 70% of the players passed away due to one of these two causes.

Heart Disease is Killing NBA Players

According to a report cited in a story by the Philadelphia-based news website Billy Penn, at least 53 retired NBA players have died from heart disease since 2000, including 33 less that were younger than 70 years old. And what really put focus on this problem were the deaths of three retired NBA players in 2015. The deaths of Anthony Mason, Christian Welp and Jack Haley in three weeks were not only alarming, but what made it more problematic were their ages. Mason was only 48, while Welp and Haley were just 51.

The fact that older NBA players are dying from heart disease and cancer isn’t different from the general population. According to the CDC, heart disease and cancer are, by far, the leading causes of American deaths.

That said, the high rate of heart complications among professional basketball players may be related to the size of NBA players and premature deaths that cannot be overlooked. It’s a pattern of mortality that most NBA players are well-aware of, as Larry Bird matter-of-factly stated in an ESPN article from a few years ago:

“I tell my wife all the time, ‘You don’t see many 7-footers walking around at the age of 75,'” says Bird, who’s 6-foot-9. “She hates it when I say that. I know there are a few of us who live a long time, but most of us big guys don’t seem to last too long. I’m not lying awake at night thinking about it. If it goes, it goes.”

The Zipper Brothers

The list could be much longer, but the growing awareness of heart issues among basketball players may have saved the lives of other NBA players with irregularities. Players like Jeff Green, Fred Hoiberg, Channing Frye, Chris Wilcox, Etan Thomas, and Ronny Turiaf have all been diagnosed with issues related to their heart and forced to take time off.  Together they’re part of a rare (and “lucky”) group of NBA players that were able to detect the abnormalities early on.

Hoiberg calls them the “Zipper Brothers” — a small and tight-knit group of players who have overcome serious heart ailments to continue playing at the highest level of a game that tests an athlete’s heart as much as any does. Hoiberg cut his NBA career short after having open-heart surgery — and getting the zipper-like scar on his chest that birthed the nickname — to address an enlarged aortic root in 2005. Thomas and Chris Wilcox were able to play after their own surgeries and Turiaf, Green and Phoenix Suns forward Channing Frye all missed a year while recovering but are still playing to this day. Chuck Hayes never needed surgery, but a heart abnormality found during a routine screening in 2011 did require significant testing before he was cleared to continue playing with Toronto.

If we’re looking outside of the NBA, there’s an unfortunately long list of players that passed away tragically playing basketball in their twenties and thirties. All it takes is some searching to see a list of other professional players, college and high school player collapsing during practice or games. It’s not limited to the professional ranks.

With more focus, research and understanding of the risks that professional basketball players face, they, their family, friends, and the league can help prevent premature deaths due to complications with their hearts.

“To us, it’s noticeable,” says Scott Rochelle, vice president and general counsel of the NBA Retired Players Association. “It’s noticeable enough for us to make this a priority.”

Back in 2015, the league’s players and retired players associations wanted to increase efforts to offer more screenings for heart complications as well as raising awareness among retired NBA players. The league had promised to will provide much more comprehensive health screenings for former players, including for heart issues.

That’s good news and a big step because by last count, the league has already lost more than fifty NBA players to heart-related deaths. Let’s not let their passing be in vein.