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.

"After some scans, blood work, and time at the hospital we learned that I had a cancerous germ cell tumor sitting in the center (of) my chest pressing majorly against my heart and lungs," he wrote. " Today we got the final diagnosis and treatment plan that has chemo starting up on Monday to shrink and hopefully eradicate the tumor entirely."