Stereotactic body radiotherapy of central lung malignancies using a simultaneous integrated protection approach :...

It is recognized that stereotactic body radiotherapy (SBRT) for centrally located lung metastases is affected by higher rates of severe toxicity. In the present study, we report the clinical outcomes following a novel intensity-modulated radiotherapy prescription dose, termed simultaneous integrated protection (SIP), for nearby organs at risk (OARs).

The prescribed total doses of SBRT were 70 Gy in 10 fractions and 60 Gy in 8 fractions. For ultra-centrally located lesions, a dose of 60 Gy in 10 fractions was delivered. The main planning instructions were: (1) to remain within the limits of the given dose constraints for an OAR; (2) to make use of the maximum possible dose to the OARs to minimize dose inhomogeneity for the Planning Target Volume (PTV). SBRT-related toxicity was prospectively assessed according to the Common Terminology Criteria for Adverse Events (CTCAE) v4.0. The primary clinical endpoint was the SBRT-related toxicity. Secondary endpoint was local control.

Forty patients affected by a single central malignancy were analyzed. The median follow-up was 20 months (range, 6-58 months). Acute and late clinical pulmonary toxicity ≥grade 2 was recorded in 2 out of 40 patients (5%) and 3 out of 40 patients (7%), respectively. No patient experienced cardiac toxicity. No narrowing or stenosis of any airway or vessel was registered. One-year local control rate was 91%. The median time to local progression was 13 months (range, 6-46 months).

SBRT using a PTV-SIP approach for single central lung metastases achieved low SBRT-related toxicity with acceptable local control.