ASTRO: Breast Cancer MRI Kinetics May Predict Nodal Status
BOSTON, Sept. 25 (MedPage Today) -- The MRI-related kinetics of a breast tumor may reveal a patient's lymph node status without surgical sampling, data from a small retrospective study suggest.
Patients with positive nodes had primary tumors with significantly greater initial peak enhancement and percent rapid enhancement on dynamic contrast-enhanced MRI compared with node-negative patients, Christopher Loiselle, M.D., of the University of Washington in Seattle, reported at the American Society for Therapeutic Radiology and Oncology meeting.
The findings have potentially major implications for patients undergoing neoadjuvant chemotherapy and for planning radiation therapy.
"When you give chemotherapy first and then perform the surgery to remove the cancer and sample the lymph nodes, you reduce the ability to know whether there was cancer in the axillary lymph nodes before chemotherapy," said Dr. Loiselle.
"This raises the question: Is there another way to stage those lymph nodes? Our study suggests that tumor characteristics on an MRI scan may be the answer."
If a tumor's MRI kinetics proves to be prognostic for lymph node status, women with smaller tumors and negative nodes might be able to avoid radiation therapy, he added.
Dynamic contrast-enhanced MRI has good sensitivity for breast cancer and provided detailed anatomic and physiologic information about malignant lesions. Whether MRI-related kinetics of the primary tumor could predict lymph node status had not been studied extensively, said Dr. Loiselle.
To assess MRI kinetics' prognostic value in breast cancer, Dr. Loiselle and colleagues retrospectively reviewed MRI records on 167 consecutive breast cancer patients treated with external beam radiation therapy.
The study included patients with MRI kinetic data who had surgical staging prior to chemotherapy. Patients who had neoadjuvant chemotherapy were excluded. Application of the eligibility criteria resulted in 46 patients for the study.
For each patient, Dr. Loiselle and colleagues calculated values for initial peak enhancement, percent rapid enhancement, and percent washout. Kinetics values were studied within the context of surgically determined lymph node status, and differences between node-negative and node-positive patients were analyzed statistically.
The analysis showed that patients with positive lymph nodes had primary tumors with significantly greater initial peak enhancement (P=0.0027).
Both mean and median values differed substantially (245% versus 144%, and 209% versus 138%, respectively).
The percent initial rapid enhancement also differed significantly between patients with positive and negative lymph nodes (P=0.0436).
Mean and median values were 48% versus 29% and 57% versus 27% for node-positive and node-negative patients, respectively.
The proportion of patients with delayed washout enhancement was similar between patients with positive and negative lymph nodes.
Receiver operating curves demonstrated area under the curve values of 0.78 for initial peak enhancement and 0.71 for initial rapid enhancement, suggesting both parameters have prognostic potential, Dr. Loiselle said.
"The application of dynamic contrast-enhanced MRI kinetics in the management of breast cancer patients could be far reaching and is worthy of further study," he said. "Among locally advanced breast cancer patients undergoing neoadjuvant chemotherapy, dynamic contrast-enhanced MRI kinetics should be investigated as a surrogate marker for traditional axillary staging."
Dr. Loiselle reported no conflicts of interest.
Primary source: International Journal of Radiation Oncology - Biology - Physics Source reference: Loiselle CR et al. "Dynamic contrast enhanced MRI kinetics and invasive breast cancer: a potential prognostic marker for radiation therapy" Int J Radiat Oncol Biol Phys 2008; 72 (1 Suppl): S176. Abstract 2018.
What breastcancer.org says about this article…
ASTRO: Breast Cancer MRI Kinetics May Predict Nodal Status
The study reviewed here suggests that certain breast cancer characteristics shown by MRI (magnetic resonance imaging) may help predict whether there are cancer cells in the lymph nodes when the cancer is first diagnosed.
The results were presented at the 2008 American Society for Therapeutic Radiology and Oncology (ASTRO) meeting.
Whether or not there are cancer cells in the lymph nodes is an important factor doctors consider when deciding if chemotherapy or radiation therapy should be given AFTER surgery to lower the risk of the cancer coming back. When breast cancer is first diagnosed, doctors often don't know if the cancer has spread to nearby lymph nodes. The nodes are examined during surgery to see if any cancer cells are present.
Chemotherapy often is given before surgery to:
- weaken the cancer
- lower the need for lymph node removal
- minimize the extent of surgery
Chemotherapy before surgery can kill all the cancer cells in the lymph nodes -- so lymph nodes that were "positive" for cancer become "negative" by the time of surgery. If this happens, doctors may decide on a treatment plan based on negative lymph nodes, which may not be accurate.
A good way to predict whether breast cancer cells are in nearby lymph nodes before any treatment starts could help make sure that women who would benefit from radiation therapy and chemotherapy after surgery get those treatments.
This small study looked at whether dynamic contrast-enhanced MRI could help determine whether cancer cells were present in nearby lymph nodes before any treatments began. While the results are promising, the study is very small and much more research is needed before dynamic contrast-enhanced MRI is used routinely to assess lymph node status.
Visit the Breastcancer.org Screening and Testing section to learn more about MRI and other techniques to screen for and diagnose breast cancer.
