According to results recently published in the Archives of Surgery, a positron emission tomography (PET) scan may be used to help predict whether breast cancer will spread to the axillary (under the arm) lymph nodes.
Early breast cancer refers to cancer that has not spread from the site of origin in the breast or the axillary lymph nodes.
Treatment for patients whose cancer has spread to the axillary lymph nodes (node-positive) often differs from that of patients who do not have cancer spread to these lymph nodes (node-negative). It is thus crucial that patients undergo testing prior to treatment to determine whether they have node-positive or node-negative disease.
Patients typically undergo a sentinel node biopsy or axillary lymph node dissection prior to therapy. Both procedures include laboratory tests to determine if cancer cells have spread to the axillary lymph nodes. However, there are side effects associated with each procedure, particularly an axillary lymph node dissection. Furthermore, producing accurate results with a sentinel lymph node biopsy requires a high level of physician training.
Researchers from the Cedars-Sinai Medical Center in California recently conducted a clinical study to evaluate the effectiveness of a PET scan to determine if cancer cells have spread to axillary lymph nodes in patients with early breast cancer.
PET scans also measure metabolic activity of a tissue. Cancer cells tend to have a higher metabolism than normal tissue, which can be determined on a PET for more accurate detection of cancer.
This study included 51 patients who underwent PET scans and then underwent either axillary dissection or a sentinel node biopsy to compare results.
- Results from the PET scan indicated that 59% of patients had node-positive breast cancer.
- All of these patients had detectable cancer cells in their axillary lymph nodes as determined by the axillary dissection or sentinel node biopsy.
- PET results identified 60% of patients with node-positive disease.
The researchers concluded that PET scans may indicate which patients with early breast cancer may be able to avoid axillary dissection or sentinel lymph node biopsy. Patients whose cancer is detected in the axillary nodes may undergo appropriate subsequent treatment. However, patients whose PET scans did not detect cancer spread to the axillary lymph nodes may still need to undergo appropriate staging since PET scans only detected 60% of patients with node-positive disease.
Reference: Chung A, Liou D, Karlan S, et al. Preoperative FDG-PET for Axillary Metastases in Patients with Breast Cancer. Archives of Surgery. 2006; 141:783-789.