Radiation Toxicity in MDA5+ and PL7-Positive Dermatomyositis: Heightened Risk in Autoimmune Subtypes.

Purpose: To increase awareness of peri-radiation therapy (RT) intervention that may unduly heighten the risk of toxicity in lung cancer patients and encourage molecular testing and pretreatment consultation with rheumatology for patients with active autoimmune conditions. Materials and Methods: A 42-year-old male with an autoimmune disease was diagnosed with non-small cell lung cancer. He received 4 cycles of pemetrexed/cisplatin with proton therapy (PT) delivered halfway through for a bronchial stump positive margin. After completing the first cycle of adjuvant chemotherapy, he was given 61.6 Gy in 28 fractionations of PT. Before restarting chemotherapy, he experienced a dry cough and later shortness of breath (SOB), which resolved with an aggressive steroid taper. After completing his third cycle of cisplatin/pemetrexed, his SOB and cough worsened. He was admitted for an urgent bronchoscopy with debridement of the distal trachea and proximal left main bronchus. He received high-dose steroids again and another bronchoscopy, revealing a tracheoesophageal fistula. Rheumatology identified an MDA5+ and PL7-positive dermatomyositis subtype at this time, known to be associated with rare ulcerative symptoms. Results: A rare MDA5+ and PL7-positive dermatomyositis subtype, discovered post treatment, most likely contributed to SOB and cough following chemotherapy and PT, resulting in bronchoscopy of the irradiated field. A combination of these factors may have contributed to the tracheoesophageal fistula. Conclusion: Patients with autoimmune disease should be carefully evaluated for rare underlying subtypes that could pose a danger to treatment. Oncologists should continue to be vigilant about underlying genetic predisposing factors that lead to exacerbated toxicity. Immunosuppressive agents given with RT may be considered for patients with autoimmune disease. Avoidance of biopsy, tissue manipulation, debridement, or any form of soft-tissue or hard-tissue violation needs to be discussed across the multidisciplinary spectrum to avoid nonhealing lesions shortly after RT.