Stereotactic body radiation therapy for stage I non-small-cell lung cancer: a historical overview of clinical studies

Abstract

Because of difficulties with stabilization, breathing motion and dosimetry, stereotactic body radiotherapy for lung cancer has only been practiced for the past 15 years. However, a large amount of case data has rapidly been accumulated in recent years. Stereotactic body radiotherapy for Stage I non-small-cell lung cancer has been actively investigated in inoperable patients since around 1995, and a number of clinical trials have been undertaken. Early studies from 2001 presented a 3-year local control rate of 94% and a 3-year overall survival rate of 66% for patients receiving 50-60 Gy in 10 fractions. Another study in 2005, using 48 Gy in four fractions, presented a 3-year local control rate of 98% and 3-year overall survival rates of 83% for Stage IA patients and 72% for Stage IB patients. A multi-institutional study showed favorable local control and survival rates in a group receiving a biologically effective dose of 100 Gy. A dose-escalation study in the USA suggested a maximum tolerated dose of 60 Gy in three fractions. A Phase II clinical trial (RTOG0236) followed, with a reported 3-year local control rate of 98% and a 3-year overall survival rate of 56% for patients who received 60 Gy in three fractions. A Japanese Phase II clinical trial (JCOG0403) investigated a dose of 48 Gy in four fractions among 165 Stage IA patients, showing a 3-year survival rate of 76% and a 3-year locally progression-free survival rate of 69% for the operable group. An overview of past clinical trials in stereotactic body radiotherapy for Stage I non-small-cell lung cancer and current issues is presented and discussed.