(RxWiki News) A person's weight may influence how accurate various medical tests are. When the test is looking for whether breast cancer has spread, it's important to know if weight makes a difference.
A recent study found that ultrasounds were just as effective at looking for breast cancer in underarm lymph nodes in overweight or obese women as in women with a normal weight.
In fact, when it came to negative findings — determining there was no cancer — ultrasounds were actually more accurate among overweight and obese women compared to normal-weight women.
Although using ultrasounds to look at lymph nodes is not the only way to see if breast cancer has spread, this method can be particularly helpful for doctors.
"Ask your doctor about breast cancer screening."
The study, led by senior author Tina Hieken, MD, of the Mayo Clinic, looked at whether ultrasounds could effectively detect breast caner in obese women's underarm lymph nodes.
It was possible that using ultrasound to look for for breast cancer would be more difficult in obese women since obesity can change the way the lymph nodes appear in imaging tests.
The researchers compared the cases of 1,331 breast cancer patients who had all received ultrasounds of the lymph nodes under their armpits.
About one third of these patients had a normal weight (33 percent), about one third were overweight (31 percent), and about one third were obese (36 percent).
The obese patients all had a body mass index (BMI) of 30 or higher. BMI is a ratio of a person's height to weight and is used to determine whether a person's weight is healthy.
However, the researchers found that ultrasound imaging was just as effective in looking at overweight and obese women's lymph nodes as in those of women with a normal weight.
For ultrasound images that showed no evidence of cancer growth, those results were actually more often accurate in overweight and obese women than in other women.
The researchers suspect that greater experience among doctors in knowing what lymph nodes look like in obese women may partly explain the results.
Another reason may be that the lymph nodes are too close to the surface of a thinner woman's skin for the ultrasound to produce as good an image as may be produced in heavier women's tests.
Dr. Hieken plans to continue studying the use of ultrasounds for lymph nodes to see if it can become accurate enough to prevent the need for axillary lymph node surgery in some patients.
Currently, a woman with invasive breast cancer still usually receives a sentinel lymph node biopsy when she has her breast surgery to be sure the cancer has not spread, even if the ultrasound was negative.
A sentinel lymph node is the lymph node that cancer cells are most likely to travel to first in a person's body, and a biopsy involves taking out a small piece of tissue from these to look for cancer.
This study was presented at the American Society of Breast Surgeons annual meeting from April 30 through May 4 in Las Vegas. The funding source and possible conflicts of interest were not reported.