Lymph Node Ultrasound Still Accurate for Obese Patients

May 9, 2014

Preoperative axillary ultrasound is effective in detecting invasive breast cancer in obese patients.

Sensitivity for preoperative axillary ultrasounds among obese women with breast cancer is similar to that of non-obese women, according to a study presented at the annual meeting of the American Society of Breast Surgeons, held in Las Vegas between April 30 and May 4.

Obesity can make physical examination of lymph nodes challenging and may alter the way they appear on imaging scans. To test this hypothesis, researchers from the Mayo Clinic in Rochester, NY performed a study to assess if obesity did, in fact, have an impact on the usefulness of preoperative axillary ultrasound (AUS). AUS is used routinely for axillary staging in patients who are newly diagnosed with breast cancer.

The researchers used a prospective breast surgery database to identify 1,510 consecutive invasive breast cancers in patients undergoing primary surgery, including axillary operations. A total of 1,375 preoperative AUS were performed (95 percent).[[{"type":"media","view_mode":"media_crop","fid":"24408","attributes":{"alt":"ultrasound","class":"media-image media-image-right","id":"media_crop_9996172987399","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"2107","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"height: 201px; width: 300px; border-width: 0px; border-style: solid; margin: 1px; float: right;","title":" ","typeof":"foaf:Image"}}]]

Median BMI of the patients was 27.4. Of the total number of patients, 36 percent were classified as obese (having a BMI of 30 or higher); 33 percent were of normal weight and 31 percent were overweight, but not obese.

The results showed that most of the tumors (71 percent) were T1 and estrogen receptor-positive (87 percent). “AUS was suspicious in 401 (29 percent) of whom 374 had US-guided lymph node fine needle aspiration (FNI),” the authors wrote. Of these, “124 patients (33.2 percent) were FNA-positive. FNA identified disease preoperatively in 35.8 percent of node-positive obese patients.”

The AUS was predictive of pathological nodal status for all women, regardless of BMI, and AUS sensitivity was the same as well. Specificity and accuracy were found to be better for women in the overweight and obese groups than for normal BMI patients.

“I think we were surprised at these results,” Tina Hieken, MD, senior author and breast cancer surgeon at the Mayo Clinic, said in a release. “It should be very reassuring that regardless of the weight of the patient, axillary ultrasound is helpful.”

Ultrasounds are not the only tool physicians use to determine if cancer has progressed. “For most patients with invasive cancer, if the axillary ultrasound is negative, we perform a sentinel lymph node biopsy at the time of the breast operation to make sure cancer has not spread,” Hieken explained.