We defined "ultracentral" lung tumors as centrally located non-small cell lung cancers with planning target volumes overlapping the trachea or main bronchi. Increased toxicity has been reported after both conventional and stereotactic radiotherapy for such lesions. We studied outcomes after 12 fractions of 5 Gy (BED10 = 90 Gy, heterogeneous dose distribution) to ultracentral tumors in patients unfit for surgery or conventional chemoradiotherapy.

Clinical outcomes and dosimetric details were analyzed in 47 consecutive patients with single primary or recurrent ultracentral non-small cell lung cancer treated between 2010 and 2015. Those irradiated previously or with metastasis to sites other than the brain and adrenal glands were excluded. Treatments were delivered using volumetric modulated arc therapy.

The median age was 77.5 years, 49% of patients had a World Health Organization performance score of 2 or higher, and the median planning target volume was 104.5cm(3) (range 17.7-508.5). At a median follow-up of 29.3 months, median overall survival was 15.9 months, and 3-year survival was 20.1%. No isolated local recurrences were observed. Grade 3 or higher toxicity was recorded in 38% of patients, with 21% scored as having a "possible" (n = 2) or "likely" (n = 8) treatment-related death between 5.2 and 18.2 months after treatment. Fatal pulmonary hemorrhage was observed in 15% of patients.

Unfit patients with ultracentral tumors who were treated using this scheme had a high local control and a median survival of 15.9 months. Despite manifestation of rates of a fatal lung bleeding comparable to those seen with conventional radiotherapy for endobronchial tumors, the overall rate of G5 toxicity is of potential concern. Additional work is needed to identify tumor and treatment factors related to hemorrhage.