Case Report of Well-Tolerated Post-Mastectomy Chest Wall and Regional Nodal Irradiation in a Patient with Cowden’s Syndrome

Purpose: Cowden syndrome, also known as multiple hamartoma syndrome, is an autosomal dominant condition that is part of a spectrum of disorders caused by mutations in the phosphatase and tensin homolog gene (PTEN). The PTEN gene is considered a tumor suppressor, and its expression is normally upregulated in response to irradiation. There is thus concern that Cowden syndrome may confer increased risk of normal tissue toxicity as well as risk of second malignancy in patients treated with radiotherapy. Data regarding the safety of irradiation in patients with Cowden’s syndrome is limited, with only a few case reports published in the literature. Of those, case reports involving breast or chest wall irradiation have described unexpected adverse effects including one case of numerous cutaneous fibromas over treated skin, and one case of unexpected breast toxicity requiring early termination of radiation. Here, we present our treatment approach for postmastectomy radiation in a patient with Cowden syndrome, demonstrating potential to reduce toxicity in this patient population.

Methodology: This is a case of a 29-year-old woman with Cowden syndrome diagnosed with left-sided invasive ductal carcinoma (IDC), clinical stage IIB (cT2 cN3b M0), estrogen and progesterone receptor positive, human epidermal growth factor receptor 2 (HER2) negative. She received neoadjuvant chemotherapy with Adriamycin/Cytoxan and Paclitaxel with partial response followed by left-sided total mastectomy and axillary nodal dissection, ypT2 N1a. She was treated with moderately hypofractionated chest wall and regional nodal irradiation to 42.56 Gray in 16 fractions at 2.66 Gy per fraction to the left chest wall using Volumetric Modulated Arc Therapy (VMAT) approach and no bolus.

Results: She tolerated radiotherapy with expected side effects of grade 1 dermatitis in the acute setting. One-year post-radiotherapy, she is well-healed from radiation, stable from a breast cancer standpoint, and has plans for a right skin-sparing mastectomy followed by bilateral breast reconstruction.

Conclusions: There is a paucity of data regarding radiation in patients with Cowden syndrome, and case reports therefore add substantial value to the body of literature surrounding this issue. Here, we report well-tolerated post-mastectomy chest wall and nodal irradiation in a young patient with Cowden syndrome, presenting a treatment approach that has potential to reduce toxicity in this patient population.

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