The introduction of new therapeutic agents in the last decade has resulted in improved survival for women with metastatic breast cancer, findings from a population-based study suggest.

As reported in the July 23rd online issue of Cancer, Dr. Stephen Chia, from the University of British Columbia in Vancouver, Canada, and colleagues assessed the outcomes of 2150 women who were treated for metastatic breast cancer during the 1990s.

The subjects were divided into four time cohorts that were constructed on the basis of when new systemic agents for metastatic breast cancer were released in British Columbia: January 1991 to December 1992, as a baseline; January 1994 to December 1995, when paclitaxel and vinorelbine were made available; January 1997 to December 1998, when the aromatase inhibitors and docetaxel were released; and July 1999 to June 2001, when trastuzumab and capecitabine were made available.

Similar baseline characteristic were noted between the groups, although subjects in the later cohorts were more likely to have estrogen receptor-positive cancer, receive adjuvant chemotherapy, and experience a longer time from initial diagnosis to metastasis.

The median survival periods for patients in cohorts 1 (1991-1992) and 2 (1994-1995) were similar, 438 and 450 days, respectively. The survival periods for cohorts 3 (1997-1998) and 4 (1999-2001) were significantly longer by comparison: 564 and 667 days, respectively.

Multivariate analysis confirmed that treatment during the late 1990s was associated with significantly better survival than treatment during the early 1990s.

“Our current population-based study of a large cohort of women with a recent diagnosis of metastatic breast cancer is the first to our knowledge that demonstrates a significant improvement in survival over time,” Dr. Chia’s team concludes.

“This improvement in survival appeared to be caused by the availability and use of newer, more effective systemic agents for the treatment of metastatic breast cancer.”