Breast MRI shows it's not the size of the lymph node that signals spread of cancer

Stephen Grobmyer, M.D., an assistant professor of surgical oncology and endocrine surgery at the UF College of Medicine. Photo by Sarah Kiewel

Stephen Grobmyer, M.D., an assistant professor of surgical oncology and endocrine surgery at the UF College of Medicine. Photo by Sarah Kiewel

Physicians treating breast cancer first look to lymph nodes in a patient’s armpit to see whether cancer is spreading elsewhere in the body — but they may not be evaluating the nodes in the most effective way.

Initial research suggested that enlargement and abnormalities of axillary sentinel lymph nodes – located in the armpit area near the breast – were predictive of cancer. But a University of Florida Shands Cancer Center researcher says it’s not the size of the node or enhancement, but the loss of a key part of a normal node’s structure called the fatty hilum that more accurately signals the spread of disease. The findings are available online in the Journal of Magnetic Resonance Imaging.

In addition to changing ideas about what doctors should look for while evaluating lymph nodes, the finding reinforces the value of using MRI to determine the extent of breast cancer prior to surgery.

“We found that the loss of fatty hilum in an axillary lymph node on MRI correlated with finding the spread of breast cancer in axillary nodes at the time of surgery,” said Stephen Grobmyer, M.D., an assistant professor of surgical oncology and endocrine surgery at the UF College of Medicine, who noted that not all nodes without fatty hilum necessarily had cancer.

The UF study retrospectively examined 56 female patients ranging in age from 30 to 82. All women had a sentinel lymph node biopsy. Fifteen women had cancer in the nodes that required complete removal. Four of eight patients in whom a loss of fatty hilum was seen in an axillary node on MRI were found to have cancerous lymph nodes at the time of their breast surgery. By comparison, only 11 out of 48 patients, or 23 percent, with all fatty hilum in place had cancer.

Grobmyer said these findings provide surgeons with another tool to help personalize medicine and evaluate factors that could indicate whether cancer has spread prior to surgery.

“I think this is another step to understanding how we can use MRI to improve care of breast cancer patients,” said Grobmyer, medical director of the UF Comprehensive Breast Center. “We are just suggesting that there may be information that people have not yet paid attention to that may impact our understanding of the staging of a patient’s disease. With this technology, if you look and see there is a node or several nodes with no fatty hilum, one would be very suspicious that there might be metastatic disease present. Instead of doing an invasive sentinel node biopsy, one could do a less invasive image-guided biopsy to obtain important staging information.”

He added it is also important that we now understand that MRI features that suggest cancer in the breast do not apply for evaluating disease in axillary lymph nodes. Currently, there is no standard MRI criterion for determining if cancer is in the nodes.

Although not routinely administered to all breast cancer patients, magnetic resonance imaging, or MRI, can offer a detailed picture of the breast, providing precise details about breast cancer locations and size. The scan is augmented through a technique known as contrast enhancement, which makes it easier to discern between cancerous and healthy tissue. The standard scan includes the axillary lymph nodes, the most common first site of spread for breast cancer.

Steven E. Harms, M.D., a radiologist with the Breast Center of Northwest Arkansas, said the accurate diagnosis of lymph node metastases is critical for patients with breast cancer, and the ability to determine their presence before the initial surgery could spare many patients the need for more than one operation.

“Over-treatment with a full axillary node removal is associated with a high incidence of lymphedema, a lifelong and often debilitating condition resulting from the disruption of lymph channels,” said Harms, who, in 2007, helped to draft the American Cancer Society breast cancer screening guidelines which recommend breast MRI screening for high risk patients.

Grobmyer said he hopes studies of a larger number of patients will further validate these findings so they can be broadly applied. He said the great advantage of an MRI is its ability to pick up more than 95 percent of invasive breast cancers.

In late 2007, UF researchers presented findings about the diagnostic value of MRI in influencing treatment plans for women, citing that it can find previously undetected cancerous areas, including cancer in the opposite breast. MRI also helps to better determine tumor size and assess an individual’s response to chemotherapy, making it useful for planning surgical procedures, UF surgeons say.