Andrey Lugovoy, who is wanted for murder by British police, has reportedly developed prostate cancer following the hit in 2006.
Litvinenko, a former Russian federal security services and KGB officer and outspoken critic of President Vladimir Putin, died in hospital after ingesting Polonium-210, a rare radioactive substance.
Ukrainska Pravda newspaper reported that investigators believe Lugovoy's tumour is related to the radioactive substance and cited findings from his medical reports that were leaked by Ukrainian cyber resistance group Inform-Napalm.
The documents also reveal that he 'refused surgery and radiation therapy' after doctors recommended 'radical treatment' for the disease, the Sun reported.
He's already getting radiation therapy....