Chicago Cubs Hall of Famer Ryne Sandberg announces cancer ...

CHICAGO (CBS) -- Hall of Fame Chicago Cubs second baseman Ryne Sandberg announced Monday he has begun treatment for metastatic prostate cancer.

Sandberg announced the diagnosis in a post on Instagram:

"I have begun treatment, and I am surrounded by my loving wife Margaret, our incredibly supportive family, the best medical care team, and our dear friends. We will continue to be positive, strong, and fight to beat this. Please keep us in your thoughts and prayers during this difficult time for me and my family," he wrote.

The prostate is a small organ that sits just beneath the bladder. Its primary function is to provide a nourishing fluid that helps transport sperm.

As men age, the prostate tends to increase in size. As the gland enlarges, it can block urine flow from the bladder. In plain English, that can make it harder to pee and lead to many middle-of-the-night trips to the bathroom.

A bigger problem is when the prostate becomes cancerous. Prostate cancer is the second-leading cause of cancer death in men.

Metastatic cancer spreads from where it started to other parts of the body.  

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Sandberg, 64, played in parts of 16 big-league seasons, almost entirely with the Cubs. 

He was drafted in 1978 by the Philadelphia Phillies – and was called up by that team late in the season in 1981. Following that season, the Phillies and Cubs exchanged shortstops – Larry Bowa came to the Cubs in exchange for Iván DeJesus – but Cubs general manager Dallas Green wanted Sandberg too, according to the Baseball Hall of Fame.

In his first season with the Cubs in 1982, Sandberg played third base and hit .271 with 33 doubles and 32 stolen bases. According to the Baseball Hall of Fame, he finished sixth in the National League Rookie of the Year voting.

Sandberg was switched to second base for the 1983 season –which the Cubs finished with a record of 71-91. But Sandberg won the first of nine straight Gold Glove Awards that year, the Baseball Hall of Fame noted.

In 1984, Sandberg was a starter for the Cubs alongside other legends such as Jody Davis, Leon Durham, and Keith Moreland. When the Cubs took on the St. Louis Cardinals at Wrigley Field on June 23, 1984, Sandberg kept driving in runs to overcome an early 7-1 Cubs deficit. But the Cubs were still down 9-8 as the bottom of the ninth began – only for Sandberg to hit a homer and tie it up.

The Cubs did not score again in the bottom of the ninth, and the game went into extra innings. St. Louis scored two more runs in the top of the 10th and took an 11-9 lead, but with two out and no one on base, Bob Dernier worked a walk from Sutter - and Sandberg hit another homer to tie the game at 11, according to the Baseball Hal of Fame.

The Cubs scored one more time on an RBI single by Dave Owen – and won 12-11. The game became known as the "Ryne Sandberg Game" and propelled the 1984 Cubs toward success that season.

The Cubs won the National League Eastern Division championship in '84 – for their first appearance in the postseason since the 1945 World Series.

While the Cubs lost the 1984 National League Championship Series 3-2, Sandberg won the National League Most Valuable Player award and made the All-Star roster for the first of 10 times. According to the Baseball Hall of Fame, Sandberg hit .314 in 1984 and led the NL in runs scored with 114 and triples with 19.

In 1989, a season in which the Cubs also won the National League Eastern Division championship, Sandberg reached the 30-homer mark, according to the Baseball Hall of Fame. According to the Baseball Hall of Fame, he led the National League with 40 home runs, 116 runs, 344 bases, 100 RBI, and 25 steals in 1990.

That year, Sandberg was the first second baseman to lead the National League in home runs since Rogers Hornsby in 1925 and the first second baseman to hit 30 or more home runs in consecutive baseball seasons, according to the Baseball Hall of Fame.

Sandberg retired after the 1997 season. 

Altogether, Sandberg amassed a career .285/.344/.452 slash line (114 OPS+) and notched roughly 68 Wins Above Replacement, per Baseball Reference. 

He was a 10-time All-Star and a winner of nine Gold Glove Awards, seven Silver Slugger Awards, and the 1984 National League Most Valuable Player Award. He was inducted into the Baseball Hall of Fame in 2005, earning more than 76% of the vote in his third year on the ballot. 

After his retirement, Sandberg served as a spring training instructor with the Cubs in Mesa, Arizona. From 2007 until 2010, Sandberg was a manager in the Cubs' minor-league system – first with the Single-A with the Triple-A Iowa Peoria Chiefs, then the Double-A Tennessee Smokies, and finally the Triple-A Lehigh Valley Cubs.

When Lou Piniella retired as Cubs manager after the 2010 season, Sandberg was a favorite to take his place. However, Cubs general manager Jim Hendry passed on Sandberg and went with Mike Quade instead.

Sandberg then left the Cubs organization and became a minor league manager for the Phillies. He served as Philadelphia's bench coach and then as manager of the Phillies for three seasons from 2013 to 2015.

Sandberg won 42.8% of his 278 contests as manager of the Phillies before being removed from the post partway through the 2015 season.

In 2016 – the year the Cubs won the World Series for the first time since 1908 under manager Joe Maddon – Sandberg returned to the team as an ambassador.

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