Luminal A breast cancer growing over 1 year in a 76-year-old woman

What happened, in summary

A 76-year-old woman presented with a vague axillary lump, although examination found no palpable breast or axillary mass. Ultrasound showed a small, benign-appearing right-breast lesion, so it was followed rather than immediately biopsied.

At 6 months the lesion measured 1.0 × 1.0 × 0.6 cm. She chose another short follow-up instead of biopsy. About 9.5 months after the first scan, it had enlarged to 1.7 × 1.5 × 1.0 cm with an irregular outline, and biopsy confirmed invasive ductal carcinoma. Staging scans showed no distant metastasis.

About 1 year after the initial imaging, she underwent right wide local excision and sentinel lymph-node biopsy. Pathology showed a 30 mm grade II invasive ductal carcinoma with associated intermediate-grade ductal carcinoma in situ, for a combined tumour extent of 40 mm. The cancer was estrogen-receptor positive, progesterone-receptor negative and HER2 negative, with Ki-67 of 20%, consistent with a luminal A profile. The sentinel node was negative. With a 30 mm tumour, a negative sentinel node and no distant metastasis, the cancer was Stage II.

A close DCIS margin prompted re-excision, which found no further carcinoma. She recovered well and completed radiotherapy. At about 4 months after surgery, adjuvant hormonal therapy was planned but had not yet started.