What happened, in summary

A 45-year-old premenopausal woman was diagnosed with neuroendocrine breast cancer, an uncommon breast cancer subtype. She had no family history of breast cancer. The tumor measured 2.0 cm and was grade 3. Six sentinel lymph nodes were examined, and all were free of cancer.

Pathology showed strong chromogranin and synaptophysin expression, supporting the neuroendocrine diagnosis. The cancer was strongly hormone receptor-positive and HER2-negative. Its estrogen receptor score was 300, progesterone receptor score was 270 and Ki-67 was 40%, a relatively high measure of tumor-cell growth.

Although the tumor was not large and had not reached the sampled lymph nodes, the high grade and Ki-67 created concern about distant recurrence. Her care team used the Oncotype DX multigene test to add information beyond tumor size and node status. The Recurrence Score was 32, above the threshold of 25 used in this case series.

The genomic result supported recommending chemotherapy. It showed that a node-negative tumor could still carry a higher-risk biological profile. The result shifted the treatment discussion toward adding chemotherapy despite the clear sentinel nodes. It gave the care team a more individualized basis for planning treatment than the pathology findings alone.