Upshaw's course of chemotherapy is expected to run through December, with a period of recovery to follow. Due to her illness and treatment, she has withdrawn from her engagements through the end of the year.

The highest-profile of those performances was to be the world premiere of Kaija Saariaho's new opera/oratorio, La Passion de Simone, at the New Crowned Hope festival in Vienna at the end of this month. Replacing Upshaw — for whom Saariaho wrote the score's only solo role — will be the Finnish soprano Pia Freund. Peter Sellars (New Crowned Hope's artistic director) does the staging, and Susanna M‹lkki conducts the Klangforum Wien and the Arnold-Sch‹nberg-Chor in three performances November 26-30 (www.newcrownedhope.org).

While in Vienna, Upshaw was also to give a November 15 performance of Osvaldo Golijov's Ayre with the Kronos Quartet; instead, Kronos will perform Golijov's The Dreams and Prayers of Isaac the Blind with clarinetist Chen Halevi.

Next month in Boston, soprano Jessica Rivera will fill in for Upshaw in John Adams's oratorio El Niê±o with the Boston Symphony Orchestra under conductor David Robertson from December 7-9.

The first US performances of La Passion de Simone were scheduled for January 12-14, 2007, with Esa-Pekka Salonen conducting the Los Angeles Philharmonic. (That orchestra and New Crowned Hope are co-commissioners of the score, along with the Barbican Centre in London and Lincoln Center in New York). Rather than give the US premiere without the singer for whom it was written, Salonen has opted to postpone La Passion de Simone to next season. (Replacing the opera on the Philharmonic's program that weekend will be Webern's Five Pieces for Orchestra and Mahler's Symphony No. 7.)

The next planned performances of La Passion de Simone are scheduled for July 10-12, 2007 at the Barbican Centre in London, with Robert Spano conducting; as of now, Upshaw fully expects to appear in them. Plans for a Lincoln Center run of the work have not yet been announced.