Pele is currently at intensive care at the Albert Einstein Hospital in Sao Paulo.
According to his medical team, the 80-year-old was "conscious, conversing actively and is maintaining normal vital signs".
"With each passing day I feel a little better," the three-time World Cup winner, who has had a number of recent health issues, said via Instagram.
He added that "I'm still going to recover for a few more days".
"While I'm here, I take the opportunity to talk a lot with my family and to rest," he said. "Thanks again for all the loving messages. We'll be together again soon!"
Following a routine test on the former Sao Paulo player, the suspected tumour was detected at the hospital where he has been having treatment since 31 August.
Pele's son Edinho, who was once a goalkeeper for Santos in February 2020 revealed that his father became worried to leave his house due to his inability to walk unaided.
Pele's health issues raised a lot of concern recently as he underwent a prostate surgery in 2015, having been admitted to hospital for the second time in six months, before being taken to the hospital again for a urinary infection in 2019.
Pele currently holds Brazil's all-time leading goalscorer and one of only four players to have scored in four different World Cup tournaments.
But saw his leading South American men's goalscorer in international matches record broken by Argentine wizard Lionel Messi after scoring a hat-trick in a World Cup qualifier against Bolivia.
