Former Brazilian president Luiz Inacio Lula da Silva on Monday had 75 percent of his tumor removed after his third and final round of chemotherapy against a throat cancer. A medical team led by doctor Roberto Kalil Filho hailed the treatment as \"impressive\" and said the ex-leader will be considered \"cured\" only if there is no recurrence in five years. The tumor was discovered in October. However, the doctors also said the surgery would affect Lula\'s vocal chords and ruled out the tumor\'s complete shrinkage. Lula\'s speech ability would not be affected, though. He is expected to undergo a radiotherapy treatment in January. Lula, upbeat after the treatment and planning to return to politics in March, said \"I am very optimistic.\"