SAN FRANCISCO – The distance of a breast cancer from a woman’s nipple added to the ability of nomograms to predict sentinel lymph node positivity, based on a study of data from 401 breast cancers.
The data came from 395 patients who had clinical stage T1 (85% of the cohort) or T2 tumors and underwent prebiopsy ultrasounds at the Mayo Clinic, Rochester, Minn. The investigators performed a second review of the images to measure the tumors’ distance from the nipple.
Nomograms published online by the Memorial Sloan-Kettering Cancer Center and by the University of Texas M.D. Anderson Cancer Center do a reasonably good job of discriminating which newly diagnosed breast cancer patients who have not undergone neoadjuvant therapy are likely to have positive and negative sentinel nodes. Using those two nomograms alone on the patients in the study produced an area under the curve (AUC) of 0.71 for the Memorial Sloan-Kettering nomogram and 0.74 for the M.D. Anderson nomogram. Adding a tumor-to-nipple distance of 2 cm or less improved the AUCs to 0.73 and 0.76, respectively, Dr. Miraj Shah-Khan and her coinvestigators reported.
Sentinel lymph nodes were positive in 20% of the 401 tumors; 17 of 33 tumors within 2 cm of the nipple had positive sentinel lymph nodes (52%), compared with 17% of 368 tumors farther than 2 cm from the nipple, Dr. Shah-Khan, of the Medical College of Wisconsin, Milwaukee, and her associates reported in a poster presented at a breast cancer symposium sponsored by the American Society of Clinical Oncology.
In each subgroup of probability predicted by the nomograms, tumor-to-nipple distance helped to refine the probability of a positive node.
When the Memorial Sloan-Kettering nomogram predicted less than a 25% chance of node positivity, adding a tumor-to-nipple distance of 2 cm or less changed the probability to 35%, compared with 11% if the distance was greater than 2 cm. A probability of 25%-49% from the same nomogram changed to 62% if a tumor was within 2 cm of the nipple or 29% for tumors farther from the nipple. A probability of 50% or greater from the nomogram changed to 100% if a tumor was within 2 cm of the nipple or 32% if it was farther away.
When the M.D. Anderson nomogram predicted less than a 25% chance of node positivity, adding a tumor-to-nipple distance of 2 cm or less changed the probability to 42%, compared with 14% if the distance was greater than 2 cm. A probability of 25%-49% from the same nomogram changed to 83% if a tumor was within 2 cm of the nipple or 40% for tumors farther from the nipple. A probability of 50% or greater from the nomogram changed to 100% if a tumor was within 2 cm of the nipple or 67% if it was farther away, she reported.
The symposium was cosponsored by the American Society of Breast Disease, the American Society of Breast Surgeons, the National Consortium of Breast Centers, the Society of Surgical Oncology, and the American Society for Radiation Oncology.
Dr. Shah-Khan reported having no financial disclosures.
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