The death of Hall of Famer Tony Gwynn has once again raised concern about the relationship between baseball and smokeless tobacco.
After a celebrated 20-year career with the Padres, Gwynn became the head baseball coach at San Diego State University.
Gwynn underwent surgeries in 1997 and 2000 to remove benign tumors from his parotid gland. In October 2010, SDSU first announced that Gwynn was suffering from cancer. He underwent surgery as well as radiation and chemotherapy treatments.
His fourth surgery in February 2012 noticeably changed his appearance and speech. During the operation, surgeons removed a tumor inside his right cheek and grafted a nerve from his shoulder to replace the nerve damaged by the tumor.
Gwynn had said he believed the cancer was caused by chewing tobacco, an addiction that started in high school and continued his whole playing career.
Smokeless tobacco has been linked to various cancers, including mouth, tongue, cheek, gum and throat cancer, according to the American Cancer Society.
Gwynn continued chewing tobacco after his first two surgeries, but said he finally quit in 2010.
"That's probably been the hardest thing I've had to deal with," Gwynn said in a 2011 interview. "The cravings are still there. I've had to try to fight them."
Gwynn had spoken against the dangers of chewing tobacco and tried to keep young people, especially his college players, from trying it.
Gwynn took a turn for the worst earlier this year. In March, he took a leave of absence from SDSU.
Smokeless tobacco is still permitted in Major League Baseball. However, a 2011 labor agreement put new restrictions in place. Players cannot use tobacco during televised interviews and must conceal tobacco products whenever fans are permitted in the stadium.
According to the America Cancer Society, in 2003, more than one-third of major league players used smokeless tobacco products.