SAN FRANCISCO – Patients with triple-negative breast cancer had no higher risk for metastases in the lymph nodes as compared with patients whose breast cancer was not triple-negative, a review of 2,957 cases found.
The study included patients with invasive breast cancer treated surgically between January 2000 and May 2012. Immunohistochemical identification of markers showed that 2,201 (74%) had luminal A subtype breast cancer (estrogen receptor– and progesterone receptor–positive and HER2 negative), 344 (12%) had luminal B subtype (all three markers positive), 144 (5%) were HER2 positive but estrogen and progesterone receptors–negative, and 278 (9%) were negative for all three markers (the triple-negative group). The study excluded men, patients treated with neoadjuvant therapy, patients with distant metastases, and those who did not undergo nodal sampling.
At least one positive lymph node was found in 35% of patients, and four or more positive nodes were found in 10% of patients.
Patients in the triple-negative group were significantly younger at diagnosis and significantly more likely to have higher-grade tumors, compared with patients with other subtypes of breast cancer. Grade 3 cancer was seen in 87% of the triple-negative group and in 27% of the luminal A group, 51% of the luminal B group, and 80% of the HER2-positive group, Dr. Alexandra Gangi and her associates reported at a breast cancer symposium sponsored by the American Society of Clinical Oncology.
In multivariant analyses, younger age, higher tumor grade, larger tumor size, and lymphovascular invasion predicted increased likelihood of lymph node metastases. The triple-negative phenotype predicted neither a higher risk for lymph node positivity nor a greater likelihood of having four or more positive lymph nodes, which was found in 9% of the triple-negative group, 9% of the luminal A group, 14% of the luminal B group, and 19% of the HER2-positive group, reported Dr. Gangi of Cedars-Sinai Hospital, Los Angeles.
The likelihood of lymph node metastases was 50% higher in patients younger than 50 years as compared with older patients, 70% higher with grade 2 cancer as compared with grade 1 cancer, and 90% higher with grade 3 cancer as compared with grade 1 cancer. Lymphovascular invasion increased the likelihood of lymph node involvement four-fold. The risk of lymph node metastases was three times higher in patients with stage T2 breast cancer and 11 times higher in patients with stage T3 disease as compared with those with stage T1 breast cancer. All of these differences were statistically significant.
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. Gangi reported having no financial disclosures.
On Twitter @sherryboschert