Case series of radiation pneumonitis in breast cancer

Radiation pneumonitis (RP) is a potentially severe inflammatory reaction that occurs in approximately 1-16% of breast cancer patients treated with radiation (RT).

Case histories and patient demographics were collected from 4 patients who received either hypofractionated (42.56 Gy in 16 fractions) or conventionally fractionated (50 Gy in 25 fractions) RT for breast cancer at a cancer centre from 2018-2020 and experienced clinically symptomatic RP. Lung dose parameters including mean lung dose, V5, and V20 were collected from institutional planning software and compared to institutional guidelines.

The 4 cases were all female, aged 42-73 years old and received 2- or 4-field RT with wide or high tangent techniques. The most common symptoms in patients who developed RP were exertional dyspnea and dry cough. Corticosteroid doses in the daily range of 40-60 mg were the primary treatment followed by a highly variable tapering schedule. Two patients experienced a recurrence of symptoms after initial treatment and were restarted on corticosteroids. Patients had several predisposing risk factors including administration of wide tangents, chemotherapy with cyclophosphamide and/or taxanes, age>65 years, and comorbidities such as diabetes.

Identification of RP is difficult as evidenced by the large gap in time between the appearance of RP symptoms to treatment with corticosteroids in several patients. Irregular tapering schedules may contribute to symptom recurrence. Three of the four patients treated with 4-field wide tangents exceeded the 35% dose constraint for ipsilateral lung V20 or V17.5.

Careful radiation planning and review of lung dose constraints is essential to reduce risk of RP. Greater standardization of steroid tapering practices is recommended.