The U.S. Supreme Court says Justice Ruth Bader Ginsburg has completed radiation therapy for a tumour on her pancreas.

The court said in a statement that a biopsy performed July 31 at Sloan Kettering Cancer Center in New York confirmed a localized malignant tumour. Ginsburg, 86, underwent a three-week course of radiation therapy and as part of her treatment had a bile duct stent placed, it said.

The court said Ginsburg "tolerated treatment well" on Aug. 5 and does not need any additional treatment but will continue to have periodic blood tests and scans.

The tumour was "treated definitively and there is no evidence of disease elsewhere in the body," the court said.

The court said Ginsburg cancelled an annual summer visit to Santa Fe but has otherwise maintained an active schedule during treatment.

Ginsburg has had several bouts with cancer beginning in 1999.

NEW: Justice Ginsburg has completed a 3 week course of radiation therapy to treat a tumor on her pancreas. “The tumor was treated definitively and there is no evidence of disease elsewhere in the body.” <a href="https://t.co/vGo8hyNRJZ">pic.twitter.com/vGo8hyNRJZ</a> —@KimberlyRobinsn

Ginsburg, who joined the court in 1993, had two cancerous nodules in her left lung removed in December. In January, she missed oral arguments for the first time in her lengthy career on the court.

The eldest of the Supreme Court justices, she is closely watched for any signs of deteriorating health. She broke three ribs last November, and was previously treated for pancreatic cancer in 2009 and colon cancer in 1999.

Pancreatic cancer is one of the hardest cancers to treat and prognoses can be bleak. According to the website of the Columbia Pancreas Center at Columbia University Irving Medical Center in New York, the percentage of people still alive five years after a diagnosis of pancreatic cancer that has not spread beyond the pancreas is 27.1 per cent.

Ginsburg, the subject of a recent documentary on her life, RBG, was nominated to the Supreme Court by then-president Bill Clinton, and took the oath of office in early 1993.

Ginsburg sits between fellow justices Clarence Thomas, left, and Stephen Breyer during the ceremonial public swearing-in of the U.S. Supreme Court's most recent justice, Brett Kavanaugh, on Oct. 8 in Washington. (Jim Bourg/Reuters)

Ginsburg, the second female justice appointed to the Supreme Court, leads the court's liberal wing. She is renowned for her work as a lawyer in the 1970s tackling gender-discrimination cases.

The 2018 movie On the Basis of Sex shared her quest for equal rights and the early cases in her historic career.

She has also become a pop culture icon affectionately referred to as the "Notorious RBG," a nickname that's a nod to the rapper Notorious B.I.G.