What happened, in summary

A woman who had been treated for adenoid cystic carcinoma at the base of the tongue also had a left breast calcification that had been monitored since 2018. As her head-and-neck cancer later spread to the lungs and brain, the breast finding became more suspicious.

After a course of paclitaxel given in the setting of progressive metastatic adenoid cystic carcinoma, the breast lesion was biopsied. Pathology confirmed a separate invasive breast carcinoma of no special type. The breast tumor was estrogen-receptor positive, weakly progesterone-receptor positive, and HER2-negative. It was an early-stage breast cancer.

Because the patient also had widespread progressive adenoid cystic carcinoma, doctors biopsied a lung lesion to determine which cancer was responsible for the metastases. The lung biopsy confirmed adenoid cystic carcinoma and excluded metastatic breast cancer. As her metastatic head-and-neck cancer continued to progress and her overall condition worsened, no breast-directed therapy was started. Care ultimately shifted to best supportive care for the advanced adenoid cystic carcinoma, while the separate breast cancer remained untreated.