U.S. Sen. Mazie Hirono says her ongoing cancer treatment has not affected her Congressional duties, and that she’s running for re-election to continue fighting for Hawaii’s families and kupuna.

“I know who I fight for and why,” Hirono said today, surrounded by supporters after signing her nomination papers.

“There are people in our country, in our communities who are being marginalized and discriminated against every single day. I fight for them,” she said. “Whether it’s families who just want health care as a right — not a privilege, or our kupuna who rely on Medicare and Social Security, or workers who want to be able to organize for better wages and conditions … for immigrants who just want a chance at a better life, or LGBTQ communities … who just want equal rights,” she said.

Hirono said she continues to undergo long-term immunotherapy treatment for cancer in her thyroid gland. The senator disclosed last year that she had been diagnosed with kidney cancer and had surgery to remove a kidney and part of her rib.

“I’ve been very open about my health challenge because I think it’s really important to let my constituents know that in spite of the fact that I am still in treatment, nothing about this treatment prevents me from doing my job,” she said. “I’m optimistic and certainly that optimism is shared by my doctors.”

Hirono said her voice in Congress “remains strong” and she’s up for the rigor of campaigning for re-election.

“If anything, I am even more vocal and visible than ever because this administration gives me a lot of opportunities to be vocal,” she said. “Every single day there’s some new thing that makes my head explode.”

No other candidates have announced that they are running for Hirono’s seat.

A former state lawmaker and lieutenant governor, Hirono was elected in 2006 to the U.S. House seat representing the Neighbor Islands and rural Oahu. She was later elected to the U.S. Senate in 2012, following Sen. Daniel Akaka’s retirement.