Dear OncoLink "Ask The Experts,"
Can you explain why PET is used in breast cancer and melanoma?
Peeyush Bhargava MD, Chief Fellow in the Department of Nuclear Medicine at the University of Pennsylvania, responds:
In patients with breast cancers, they are performed to monitor therapy and to detect recurrent disease. In patients with high clinical suspicion for recurrence but unclear findings on conventional imaging techniques (mammogram, CT), PET scans provide more information about the disease status.
In patients with advanced disease (breast cancer or melanoma), PET scans are very helpful to determine the involvement of lymph nodes and for evaluation of spread of cancer to other parts of the body.
Figure 2 shows the images of a patient with breast cancer and how useful PET scan can be to identify all the cancerous tissues in the body, not visible on the other scans.
Figure 2 shows images from a patient with breast cancer. Image 1, 2 and 3 are from a recent CT scan and images 4, 5, 6 and 7 are from the PET scan. Patient was diagnosed with breast cancer on the left side many years ago and underwent surgery and chemotherapy. On a recent CT scan (image1 and 3) multiple enlarged lymph nodes are seen. Image 2 shows a spot in the lung which is worrisome for cancer. Image 1 on the CT scan corresponds with image 4 on the PET scan, image 2 to image 5 and image 3 to image 6 respectively. Image 7 is the whole body projection image. Image 4 confirms the enlarged lymph nodes seen in image 1 to be cancerous because they are so active (black in color). Image 5 confirms the spot in the lung to be cancerous; image 6 confirms a lymph node to be cancerous and also shows that there is a new cancer in the right breast. This patient had a normal mammogram of the right breast 4 months before the PET scan. The projection image (image 7) shows the different cancerous areas/foci in a better view. The PET scan changed the management in this patient and identified a new breast cancer on the other side.