Physicians validate reclassification of breast cancer stages

Jun 7 2006

Breast cancer is diagnosed as having progressed to any of four stages, Stage IV being the most advanced. The stages are classified by the American Joint Committee on Cancer (AJCC) on the basis of how much the cancer has spread.

In 2002, the AJCC updated its classification system for breast cancer with the publication of its sixth edition of the AJCC Cancer Staging Manual. Now scientists at Oregon Health & Science University Cancer Institute have learned that because of the reclassification, some breast cancer patients may have a higher probability of disease-free survival than previously thought.

The results of the study will be presented on June 5 at the 2006 annual meeting of the American Society of Clinical Oncology in Atlanta, Ga. The presentation is one of eight abstracts either authored or co-authored by members of OHSU's Department of Radiation Medicine to be accepted for presentation at the conference.

"The changes made in the 6th edition of the AJCC guidelines are validated by our study," said Parag Sanghvi, M.P.H., M.D., resident in radiation medicine, OHSU, and one of the study authors. "The reclassification of Stage II and III patients improves our ability to predict prognosis in terms of disease-free survival."

The study analyzed 4,810 patients who were treated at either St. John Medical Center in Longview, Washington, or Southwest Washington Medical Center in Vancouver. Each patient was assigned a disease stage based on both the 5th and 6th editions of the guide.

Patients ranged in age at diagnosis from 20 to 99, with a mean age of 60. The mean length of disease-free follow-up was 224 months (more than 18 years).

The revisions occurred in the two middle classifications, Stages II and III, improving 10-year survival rates in both categories.

As a result of the changes, 13 percent of the patients previously diagnosed with Stage II breast cancer would now be diagnosed with Stage III. Thus, the 10-year survival rate for those with Stage II breast cancer improved, from 66 percent (5th edition) to 72 percent (6th edition). For those with Stage III, the 10-year survival rate also improved, from 30 percent to 36 percent.

The 6th edition classification system has been required for use for cases diagnosed since January 1, 2003.

The study's lead author is Eugene Kim, an undergraduate at Case Western University, in collaboration Sanghvi; Choong R. Kim, M.D., adjunct clinical faculty at OHSU and a physician at St. John Medical Center; Carol Marquez, M.D., associate professor of radiation medicine, OHSU; and Charles R. Thomas, Jr., M.D., professor and chair of radiation medicine, OHSU.