Manila: Philippine Senator Miriam Defensor-Santiago will see out her final days in office resting, as she remains on medical leave due to cancer.

Defensor-Santiago, 70, wrote to Senate President Franklin Drilon on Tuesday saying she would not be taking up any duties related to her work as an Upper Chamber legislator, as she is suffering from the side-effects of anti-cancer medication.

“This signifies that I shall continue on medical leave for cancer. One of the medications has produced a side-effect of anorexia [difficulty of eating] which renders me physically and mentally weak,” she said.

Defensor-Santiago surprised political watchers when she announced in mid-2015 that she would be running for the presidency again, despite being diagnosed by doctors last year for Stage 4 lung cancer.

Defensor-Santiago of the Peoples Reform Party ran for president in the May 9, 2016, with Senator Ferdinand Marcos Jr as her running mate.

She finished last in a field of five candidates in the recent polls with Rodrigo Duterte emerging as the presumptive president.

Marcos Jr is still contesting the result of the elections where his rival for the same post, Liberal Party bet Leni Robredo is widely regarded as the poll winner.

“After losing her bid for the presidency, Sen. Miriam Defensor Santiago will finish the last days of her term resting,” an entry, dated May 24, on the senator’s Facebook page said.

Defensor-Santiago’s loss in the presidential race was her second. In 1994 she was defeated by Fidel Ramos in the hotly contested elections.

On January 2015, she had announced that she would go on “qualified medical leave” while seeking treatment for lung cancer in the US.

The senator, known for her witty one-liner jokes, never did go on an extended leave and instead continued on with her duties at the senate.

Despite her medical condition Defensor-Santiago had remained active and prolific.

She holds the distinction of being the senator who has filed the highest number of bills and resolutions.

Santiago has filed more than 1,000 bills and resolutions.