According to this article from NPR, Justice Ruth Bader Ginsburg had surgery on December 21st for early stage lung cancer.
Short of complications in recovery, doctors say prospects look good for a full recovery for Ginsburg, 85. She hopes to be back on the court for the start of the next argument session in early January.
The cancer was discovered after Ginsburg fell, fracturing several ribs in November. In taking CT scans of her ribs, doctors noticed an abnormality in one lobe of the lung. Subsequent biopsies and other initial tests revealed two non-small cell cancerous lesions, with no lymph node involvement detectable.