Breast cancer linked to a rare kidney condition believed to be cancer-related

What happened, in summary

A 55-year-old woman was being evaluated for persistent blood and protein in her urine when she noticed a lump in her right breast. Imaging found a breast lesion without suspicious distant disease. Biopsy showed grade 1 invasive ductal carcinoma that was estrogen receptor-positive, progesterone receptor-positive, HER2 1+, and had a low Ki-67 level of about 5-10%. The cancer was classified as Stage IIA, T2N0M0.

Because surgery was not immediate, she began tamoxifen as preoperative hormone therapy. Seventy-five days later, she underwent right partial mastectomy and sentinel-node biopsy. The surgical specimen showed carcinoma in situ with clear margins, and the sentinel node contained no cancer. She then received breast radiation. Tamoxifen was later changed to letrozole, 13 months after treatment began.

Her kidney work-up showed an unusual IgA-dominant inflammatory pattern that was considered possibly related to the breast cancer. Prednisolone was used for the kidney condition. As the cancer was treated, the urinary findings also improved.

About 15 months after hormone therapy began, blood in the urine had resolved and the amount of protein in the urine had fallen substantially. At the latest follow-up, she had excellent daily functioning and no evidence of local or distant breast-cancer recurrence. She remained on follow-up for both the breast cancer and the kidney condition.

The breast and kidney problems were managed together because the urinary findings improved after both cancer treatment and immune suppression. She continued endocrine therapy to reduce breast-cancer recurrence risk. No cancer was found in the sentinel lymph node at surgery.