She lost a 1 1/2-year battle with stomach cancer in 2007, when he was playing for the Mets.
"You have to learn to deal with it, but it's still hard," he said. "My sister was only 31 when she died. She had a daughter, who is living with my mom in Venezuela."
Seven-year-old Jimneidy has a strong support system.
"All of our family is taking care of her," he said.
Major League Baseball once again turns its attention to a deadly disease this Mother's Day. Pink ribbons, pink wristbands and pink bats are in vogue as big league players participate in the annual "Going to Bat Against Breast Cancer" initiative by MLB that raises awareness about breast cancer and directs massive proceeds to Susan G. Komen for the Cure.
The pink ribbon logo will appear on the bases and on commemorative home plates, and the lineups will be written on pink cards.
The bats, along with the home plates and lineup cards, will be autographed by the teams and will be auctioned later on MLB.com, with the proceeds going to the Breast Cancer Foundation.
Pink bats have become an annual Mother's Day symbol at big league ballparks.
Last season, Jose Vidro, Raul Ibanez, Richie Sexson, Adrian Beltre, Yuniesky Betancourt, Jeff Clement, Willie Bloomquist, Miguel Cairo, Jose Lopez and Jamie Burke used pink bats, joining more than 200 Major League players going pink for a day.
Chavez, who didn't play in that Mother's Day game against the Reds, was one of nine Mets that ordered pink bats from Louisville Slugger.
He hopes to be in the Mariners' lineup so he can use a pink bat in a game for the first time.
"I really want to support the cause because I know how we all fought and what we went through," Chavez said. "I'd love to add strength to the fight against cancer."
The memories of two summers ago, during his final visit to the New York hospital where his sister passed away, remain fresh in his mind.
"It's something that is still hard to explain," he said. "When she got sick, she thought it was the flu, so she never went to the doctor to get checked out. She didn't think it was necessary.
"By the time she saw a doctor, the cancer was pretty advanced."
The illness became progressively worse.
"She was in Venezuela and I finally talked her into coming [to the United States] to see a doctor," Endy said. "She had surgery and seemed to be improving. After about eight to 10 days, she started getting back to normal and we were all excited.
"She showed improvement for about two months, but had a relapse and that was it. The cancer was so strong that there was nothing the doctors could do for her. She kept getting worse every day. It was tough."
The Mets were in the midst of a homestand when the end came for Chavez's sister.
"I went to the hospital the night before she died," he said, "and I knew I would not see her again. We knew what was going to happen. The only thing in her body that was working was her heart.
"I saw her that night and said goodbye to her. She died the next day."
Chavez said it was one of the worst experiences of his life, but it "is something you have to deal with. One of the things I learned from it is if you don't feel right, go right to the doctor. I just think she waited too long.
"It's tough," he added. "I hope we can find cure so other people will not have to go through something like this."