Robi Draco Rosa -- a former member of the Latin boy band Menudo -- has announced he's been diagnosed with cancer.
Rosa's manager released a statement ... explaining how doctors discovered a cancerous tumor in the singer's abdomen, near his liver.
The 41-year-old singer is currently receiving treatment at a clinic in Houston, TX.
Rosa joined Menudo in 1984 and stuck with group until '87. After the boy band years, he struck gold working with Ricky Martin -- writing and producing "Livin' la Vida Loca" and "She Bangs."