* Treatment follows cancer operations on communist-run
island
* May receive therapy for side effects of radiation
treatment
* President has made no public appearance in nearly two
weeks
CARACAS, Nov 27 (Reuters) - Venezuelan President Hugo Chavez
will travel to Cuba on Tuesday for medical treatment, following
a nearly two-week absence from the public eye, months after
undergoing cancer surgery on the communist-run island.
Chavez, 58, underwent what appeared to be a remarkable
comeback from an undisclosed type of cancer diagnosed in June
2011. In October, he won re-election despite running a campaign
that was much more subdued than his previous bids.
In a letter to Congress, Chavez said he would receive a form
of therapy known as hyperbaric oxygenation, which is often used
for the prevention and treatment of bone decay caused by
radiation therapy, according to the American Cancer Society.
Chavez has not appeared in public in 12 days. The absence is
unusual for a leader who routinely chats for hours during live
broadcasts, and suggests his health has weakened since the
campaign.
"Six months after I completed the last radiation therapy
treatment, it has been recommended that I begin a special
treatment consisting of various sessions of hyperbaric
oxygenation," Chavez wrote in the letter, which was read by
congressional leader Diosdado Cabello.
"Together with physical therapy, (this) will consolidate the
process of strengthening my health."
The letter did not mention cancer.
Hyperbaric oxygenation therapy, also known as HBOT, involves
breathing pure oxygen while in a pressurized chamber.
Chavez's centralization of power and enormous control over
the country's oil revenue have made him the center of the OPEC
nation that provides about 10 percent of U.S. crude imports.
If his health took a turn for the worse, his unwieldy
coalition of military leaders and leftist social activists could
fall apart. Investors hoping for a more market-friendly
government tend to buy Venezuela's widely-traded bonds on
reports his health is worsening.
The country's benchmark Global 27 bond
extended gains in the wake of the announcement.
It was not clear how long Chavez would stay in Havana. An
official at Brazil's foreign ministry told Reuters that
Venezuela's embassy in Brazil said he was still expected in
Brasilia for a regional summit on Dec. 7.
CANCER STILL SECRET
Chavez's refusal to disclose his actual condition has made
his health the subject of constant speculation, particularly
among some opposition sympathizers who quietly hope he will take
a turn for the worse. He defeated opposition challenger Henrique
Capriles by 10 percentage points in the election last month.
Late last year Chavez declared himself completely cured of
cancer, but within months he had to return to Cuba for surgery
to remove another tumor.
Some opponents of the president took to Twitter on Tuesday
with jabs at the former soldier's followers, repeating the
message: "#FooledChavistas, you voted for Chavez! They made you
believe he had been cured!"
But the usually feverish speculation has been muted by the
approach of the holiday season and a general weariness with
politics after a year of campaigning.
Doctors say a couple of years must pass without a recurrence
before a patient is said to be cured of cancer.
In addition to the bone-weakening side effects of radiation
therapy on cancer sufferers, experts say HBOT is used to treat
conditions including infections, abscesses and decompression
sickness which can afflict deep sea divers.
"It is a palliative treatment that is very common for cancer
patients, and often lasts for several months," said a Venezuelan
medical source with knowledge of Chavez's treatment.
The medical source said HBOT is normally given at a rate of
two or three sessions per week, and could also be used to treat
damage done by radiation therapy to patients' digestive systems.
Many Venezuelan doctors suspect Chavez used steroids and
other treatments to look and feel fit during the election
campaign, which could have caused him other health problems.
Chavez spent several months traveling back and forth to Cuba
to receive treatment. The typically hermetic atmosphere there,
and his friendship with former leader Fidel Castro, helped
prevent details of his condition from leaking to the press.
Venezuela's constitution says that if an incumbent leaves
office in the first four years of a six-year term, a new
election must be held.
Chavez's treatment could make it difficult for him to help
allies campaign ahead of Dec. 16 elections for state governors,
which will be key to expanding his control over the provinces.
His allies, who run 15 of the country's 22 states, have
considerably less popular appeal than he does and can get a leg
up at the elections if Chavez joins them at rallies.
A prolonged absence could also slow the pace of key economic
policy decisions, which often depend on his direct approval.
Most economists expect Venezuela will devalue its bolivar
currency after heavy spending in the run-up to the October vote.
The currency has weakened sharply in the country's black
market for U.S. dollars in recent months - the dollar now trades
at almost four times the official rate of 4.3 bolivars.