The 2003 revision of the Tumor-Node-Metastasis classification system is effective for predicting relapse and survival in women with locally advanced breast cancer who receive chemotherapy prior to surgery, according to an article in the August 3rd issue of the Journal of the National Cancer Institute.

Neoadjuvant therapy is typically used for locally advanced breast cancer, where tumors are 3 centimeters or larger in diameter, because shrinkage may make subsequent surgical removal easier, said Dr. Lisa Carey, associate professor of medicine in the UNC School of Medicine’s Division of Hematology/Oncology and the report’s lead author.

“You can actually measure the response of the tumor to the chemotherapy, and we have found it may improve the likelihood of having a lumpectomy instead of mastectomy,” she added.

The amount of residual tumor remaining after chemotherapy has important implications for survival. “A woman whose tumor is obliterated, where none remains after the chemotherapy, has a better outcome five years later than a woman who still has cancer left in the breast.”

However, debate has focused on the best way to measure that residual amount, Carey added. “So our study looked at the revised AJCC TNM classification system to determine if it was helpful for predicting outcome. And using the same data set, we also compared the system with several other classification methods that have been used in clinical trials.”

The TNM system was developed as a tool for doctors to stage different types of cancer based on certain standard criteria. In breast cancer, it is based on the extent of the tumor in the breast, the extent of spread to axillary lymph nodes, and the presence of metastasis.

Once criteria are determined, they are combined and an overall “stage” of I, II, III or IV is assigned. Sometimes these stages are subdivided as well, using letters such as IIIA and IIIB.

The current study included 132 patients with locally advanced breast cancer who had been diagnosed with clinical stage II or III disease, according to the 1988 TNM system. All had been treated at one university medical center in neoadjuvant chemotherapy clinical trials followed by surgery from January 1992 through December 2000.

Using surgical tissue samples from each patient’s breast and axillary lymph nodes, the researchers measured the pathologic stage of the patients’ residual tumor with the revised TNM staging system. They then looked at the association between tumor stage in surgical specimens and five-year disease outcome.

After a median of five years, residual tumor stage as measured by the revised TNM system was strongly associated with both distant disease-free survival and overall survival. A higher stage of residual tumor after neoadjuvant chemotherapy was associated with a statistically significantly lower rate of disease-free survival.

“Before the revisions, the AJCC system didn’t take into account the number of nodes that had cancer left in them very well,” Carey said. “It didn’t emphasize the difference in prognosis between a woman with one lymph node with cancer and women who have 10 lymph nodes with cancer.

“There were other changes to the system, but that was the most relevant for our study. The new system has been widely adopted, and now we know that it can give us very useful information about how to assess the response to neoadjuvant chemotherapy.”