Secretory breast cancer: mastectomy and radiotherapy to no evidence of disease

What happened, in summary

A 65-year-old postmenopausal woman sought care for a painless right-breast mass she had noticed during self-examination 5 months earlier. She had no personal or family history of breast cancer. Examination found a hard 3.5 cm mass at the junction of the superior external quadrant and retro-areolar area, plus a mobile right axillary lymph node measuring 1.5 cm. Mammography and ultrasound showed an irregular right-breast mass and axillary adenopathy, classified as BI-RADS 5. Tru-Cut biopsy first suggested SBR grade 2 infiltrating ductal carcinoma. CT of the chest, abdomen, and pelvis showed no distant metastases. She underwent right mastectomy with ipsilateral axillary lymphadenectomy. Final pathology refined the diagnosis to infiltrating secretory-type breast carcinoma, measuring 22 mm, SBR grade 2. There were no vascular emboli or perineural invasion. A high-grade in situ component with multifocal comedo necrosis made up 10% of the tumor, and tumor-infiltrating lymphocytes were estimated at 60%. The nipple and skin were not involved, there was no Paget disease, and all 12 removed axillary lymph nodes were non-metastatic. Immunohistochemistry was negative for estrogen receptor, progesterone receptor, and HER2, confirming a triple-negative subtype; Ki-67 was 50%. The final classification was pT2N0M0. A multidisciplinary team recommended adjuvant radiation without chemotherapy. She received hypofractionated 3D conformal radiotherapy to the right chest wall, 42 Gy in 15 fractions over 18 days, with good tolerance and no significant side effects. As of May 2024, 6-month follow-up showed no clinical or radiologic evidence of relapse, and she remained on regular clinical surveillance afterward in follow-up clinic.