SAN ANTONIO – December 9, 2004, Kaiser Permanente researchers are presenting results of a large epidemiologic study of a unique breast cancer test at the 27th Annual San Antonio Breast Cancer Symposium. The KP study shows the test can identify patients with early stage disease who are at low risk of breast cancer death at 10 years.
Researchers at Kaiser Permanente designed a population-based,
case-control study that evaluated node-negative,
non-chemotherapy-treated breast cancer patients diagnosed between 1985
and 1994 at 14 Northern California Kaiser hospitals. The study among KP
members (790 cases and controls) included many patients with small
tumors, as seen in current practice -- more than 30 percent had tumors
less than or equal to 1 cm in size.
The results of the study showed a strong and graded association between
the Oncotype DX “Recurrence Score” and 10-year breast cancer mortality
(p<0.001). These new results in a community-based patient population
representing approximately one percent of the U.S. population were
similar to those from the large clinical validation trial conducted
previously by the National Surgical Adjuvant Breast and Bowel Project
“Our study is significant because it reinforces the NSABP validation
study findings but in a community-based patient population,” said Laurie
Habel, Ph.D. leader of the Northern California Kaiser Permanente study.
“The results demonstrate a strong and graded association with breast
Using quantitative RNA analysis of tumor tissues, the study evaluated
the Oncotype DX breast cancer assay and compared its use with standard
measures of tumor size and tumor grade. The assay provided information
that goes beyond tumor size and tumor grade. In addition, the assay
identifies a large proportion of women who have a very low risk (less
than 3 percent) of breast cancer death at 10 years.
The Kaiser study is one of the first to evaluate a multi-gene panel in a
large community-based cancer patient population. The assay, Oncotype
DX, used in this study includes 21 genes related to the estrogen
receptor, HER2, proliferation and invasion as well as several other
carcinogenic pathways. Oncotype DX assay has been developed and
validated by Genomic Health in multiple independent studies involving
over 2,600 patients. Kaiser Permanente’s study was sponsored by Genomic