The voluntary patient, in her 60s, has schizophrenia and is not in a position consent to an operation, the court heard.
The HSE sought a declaration that it was in her best welfare that she receive all appropriate treatment for low-grade invasive ductal carcinoma of the right breast.
It also sought an order permitting doctors to take all necessary steps to assess, prioritise and treat her by mastectomy.
HUNT ON FOR FINAL NAZIS
A campaign aimed at tracking down the last Nazi war criminals has been launched in Germany.
Jewish human rights group the Simon Wiesenthal Centre has put up 2,000 posters depicting the entrance gate of Auschwitz in the cities of Berlin, Hamburg and Cologne, asking the public to come forward with information that may lead to the arrest of Nazis 70 years after the end of Hitler's Third Reich.
The centre estimates there are about 60 people who are still fit to stand trial.
US IMMIGRATION MOVE ATTACKED
A White House senior adviser is accusing Republicans of "cruel hypocrisy" for contemplating legal status for unauthorised immigrants brought to the US as children – without legalising their parents.
Dan Pfeiffer's comment comes as the House Judiciary Committee prepares to convene a hearing on what to do about immigrants brought illegally to the US as children.
House Republican leaders have endorsed a path to citizenship for some immigrants, but Democrats are holding out for comprehensive legislation.
THEFT LEAVES SEAGULLS SILENT
The 1980s band Flock of Seagulls says someone flew off with $70,000 of its equipment during a southern California gig.
Frontman Mike Score said someone stole the band's rented van at around 2am on Sunday.
The stolen gear included stage clothing, guitars, drums, a keyboard and hard drives containing the songs for his first solo album.