The newspaper said Marcum, who has struggled this season after signing a one-year, $4 million deal with the Mets in the offseason, is suffering from thoracic outlet syndrome and will undergo corrective surgery Monday.
The condition, caused by compressed nerves or arteries between the collarbone and rib cage, has resulted in tingling and numbness in his throwing hand, ESPN.com reported.
The 31-year-old hurler has gone 1-10 with a 5.29 earned run average in 14 games (including 12 starts) after spending time on the disabled list early in the season with a neck injury.
Before signing with the Mets, Marcum compiled a 20-11 mark with a 3.60 ERA in 54 starts over two years with the Milwaukee Brewers.
Millions of Getty images now available for free via embed tool
Boston schools pull out free condoms over wrapping complaints