Former Argentine soccer player Diego Maradona (L) speaks with Venezuela's President Hugo Chavez and former Cuban leader Fidel Castro (C) during a meeting in Havana in this handout photo taken July 23, 2011. [Photo/Agencies]

CARACAS, Venezuela - Venezuelan President Hugo Chavez sang and recited a poem in honor of independence hero Simon Bolivar on Sunday, appearing upbeat and energetic after his first week of chemotherapy in Cuba.

Chavez said in a televised speech that he is optimistic he will survive cancer, but added that risks remain and that he is under strict orders from his doctors to limit his agenda. After returning to Caracas on Saturday night, Chavez said thorough tests have found no signs that any cancer cells have reappeared.

Chavez spoke at the childhood home of Bolivar on the anniversary of his birth, praising the legacy of the founding father after whom the president named his socialist-inspired Bolivarian Revolution movement. Chavez declared: "Long live Simon Bolivar, now and forever!"

Chavez also recited a poem about Bolivar by Chilean poet Pablo Neruda, and sang outside the house with a folk music group while a crowd of supporters cheered.

Chavez said he initially hadn't been sure he would make it in time for the annual celebration.

"It depended on how things went in the first stage" of chemotherapy, Chavez said. He was in Cuba throughout last week, and said Friday that he successfully completed his first cycle of chemotherapy.

The president underwent surgery in Cuba on June 20 to remove a cancerous tumor, which he said was the size of a baseball. He hasn't said what type of cancer he has been diagnosed with or specified where exactly it was located, saying only that it was in his pelvic region. He says chemotherapy is necessary to ensure cancer cells don't reappear.

Chavez said that a day after he arrived in Cuba on July 16, he underwent thorough medical imaging tests, and that Fidel Castro brought him good news afterward.

"He told me three words: 'You don't have anything,"' Chavez said. He said the exam found that throughout his body there was no sign of any "malignant cell that had escaped the place where the tumor was."

Chavez added: "Not in the place where the tumor was either. And that was the spot most checked, of course."

However, he said, "This doesn't mean that there is no risk."

Chavez said he will limit his agenda to comply with his doctors' recommendations.

"I should take very, very, very good care of myself," Chavez said.

Castro has been at Chavez's side throughout much of his treatment in Cuba. Chavez said his friend and mentor urged him not to overexert himself and told him: "Rein in the horses. Don't believe that everything is already solved, and the people shouldn't believe it. The people have to know."

Chavez said the former Cuban president also told him: "We're winning this battle and we will win it, but a stretch still lies ahead to win it. And you have to take care of yourself."

After his return to Caracas on Saturday night, Chavez said he soldiered through the week of chemotherapy with only minor discomfort. He said he will undergo additional phases of treatment, but did not say how long the process could last.

"I've come back better than I left," said Chavez, who strode away from the plane down a red carpet while troops stood at attention.

Chavez said he was closely following events in Venezuela throughout his stay in Cuba. He kept up a steady stream of messages on his Twitter account, ranging from government announcements to rooting for the national soccer team.

The leftist president, who has been in power since 1999, has said he intends to run for re-election in late 2012 despite his illness.