after six seasons in the nhl, koivu was diagnosed with burkitt's lymphoma, a non-hodgkin's lymphoma. on september 6, 2001, and missed nearly the entire 2001–02 season. koivu was on his way back from finland with canadiens teammate brian savage, who said he looked pale. he was suffering serious pains in stomach and vomiting and went to see the canadiens' physician david mulder, who, after several tests, discovered the cancer. koivu received large numbers of get-well e-mails and letters from fans and was also in touch with mario lemieux and john cullen; hockey centres who had beaten cancer and made successful returns to the nhl.