Phrenic nerve palsy after repeated radiation for left breast cancer

What happened, in summary

A 66-year-old woman had a long history of separate cancers in the left breast. She underwent lumpectomy for lobular carcinoma in 2000, followed by another lumpectomy and brachytherapy for ductal carcinoma in 2004. Years later, a change in the contour of the breast led to ultrasound, mammography, and biopsy, which found a new stage IA, T1aN0M0 invasive ductal carcinoma.

Because of the repeated malignancies, mastectomy was offered. She declined and chose another wire-localized lumpectomy followed by radiation. The later radiation course delivered 4500 cGy using tangential fields.

Soon after radiation began, she reported shortness of breath. One month after completing treatment, her home oxygen saturation fell below 85%, with fatigue and a need for continuous supplemental oxygen. Testing did not support infection, heart failure, or an obstructive lung exacerbation. Chest imaging showed new paralysis of the right side of the diaphragm.

She received intravenous methylprednisolone in the emergency department followed by four days of prednisone. Her breathing improved, and she was discharged on room air with pulmonology follow-up. Additional imaging found no spinal metastasis or another clear structural cause of phrenic nerve injury. The clinicians considered repeated chest-wall radiation the most likely explanation for the right phrenic nerve palsy.

The case illustrates how cumulative treatment across multiple breast-cancer episodes can complicate a later care course. Her earlier cancers and radiation are included because they were central to understanding the nerve injury, while the stage fields refer specifically to the most recent invasive ductal carcinoma. The respiratory complication became the main clinical issue after completion of local treatment for the latest breast cancer.