Brachial plexopathy from stereotactic body radiotherapy in early-stage NSCLC: dose-limiting toxicity in apical tumor sites.

BACKGROUND AND PURPOSE: We report frequency of brachial plexopathy in early-stage non-small cell lung cancer treated with stereotactic body radiotherapy.

MATERIALS AND METHODS: 276 T1-T2, N0 or peripheral T3, N0 lesions were treated in 253 patients with stereotactic radiotherapy at Indiana University and Richard L. Roudebush VAMC from 1998 to 2007. Thirty-seven lesions in 36 patients were identified as apical lesions, defined as epicenter of lesion superior to aortic arch. Brachial plexus toxicity was scored for these apical lesions according to CTCAE v. 3.0 for ipsilateral shoulder/arm neuropathic pain, motor weakness, or sensory alteration.

RESULTS: The 37 apical lesions (19 Stage IA, 16 IB, and 2 IIB) were treated with stereotactic body radiotherapy to a median total dose of 57 Gy (30-72). The associated brachial plexus of 7/37 apical lesions developed grade 2-4 plexopathy (4 pts--grade 2, 2 pts--grade 3, 1 pt--grade 4). Five patients had ipsilateral shoulder/arm neuropathic pain alone, one had pain and upper extremity weakness, and one had pain progressing to numbness of the upper extremity and paralysis of hand and wrist. The median of the maximum brachial plexus doses of patients developing brachial plexopathy was 30 Gy (18-82). Two-year Kaplan-Meier risk of brachial plexopathy for maximum brachial plexus dose >26 Gy was 46% vs 8% for doses 26 Gy (p=0.04 for likelihood ratio test).

CONCLUSIONS: Stereotactic body radiotherapy for apical lesions carries a risk of brachial plexopathy. Brachial plexus maximum dose should be kept <26 Gy in 3 or 4 fractions.