ST. PETERSBURG, Fla. (AP) — Tampa Bay Rays minor league pitcher David Hess says he is starting chemotherapy to treat a cancerous tumor in his chest.

Hess tweeted Wednesday that he went to an emergency room about a week ago after experiencing chest tightness and shortness of breath.

The 28-year-old Triple-A right-hander said scans and blood work helped reveal a “cancerous germ cell tumor” in his chest that was pressing against his heart and lungs.

He plans to begin chemo next Monday and is hoping to return to baseball after treatment.