SABR the treatment of choice for inoperable stage 1 NSCLC

Lung cancer

By Mardi Chapman

4 Mar 2019

Prof David Ball

Stereotactic ablative radiotherapy (SABR) should be the treatment of choice for patients with inoperable peripherally located stage 1 non-small cell lung cancer (NSCLC), say the Australian authors of a phase 3 trial published in Lancet Oncology.

The randomised CHISEL trial conducted across 14 hospitals in Australia and New Zealand randomly assigned 101 patients with peripherally located stage 1 NSCLC who were either unfit for surgery or refused surgery to either conventional radiotherapy (n=35; 66 Gy in 33 fractions of 2 Gy or 50 Gy in 20 fractions of 2·5 Gy) or SABR (n=66; 54 Gy in three 18 Gy fractions or 48 Gy in four 12 Gy fractions).

SABR achieved improvements in freedom from local failure, the primary endpoint (hazard ratio for SABR vs standard radiotherapy 0·32 [95% CI 0·13–0·77], p=0·008).

The secondary endpoint of 2-year overall survival was achieved by 77% (95% CI 67–88) of the SABR group compared to  59% of the standard radiotherapy group.

Treatment was generally well tolerated in both treatment groups.

According to the study authors led by Professor David Ball from the Peter MacCallum Cancer Centre in Melbourne, the study is the first randomised trial to compare SABR with standard radiotherapy in patients who had pathologically proven non-small cell lung cancer at stage T1–T2aN0M0, determined by FDG-PET scanning.

It is also the first trial to take into account tumour motion, either with 4D CT (for patients randomly assigned to SABR) or FDG-PET scanning (for patients randomly assigned to standard radiotherapy).

“The improvement of both local control and overall survival with SABR shown in this prospective randomised trial provides, to our knowledge for the first time, evidence supporting stereotactic ablative radiotherapy as the standard of care for the treatment of inoperable peripherally located stage 1 (T1N0M0 and T2aN0M0) NSCLC,” they concluded.

In an accompanying editorial Faiez AlShafa and David Palma from the Division of Radiation Oncology, London Health Sciences Centre, Canada, described the trial as a “major step forward” and one that we could learn a number of lessons from – including that the benefits of new technologies can be proven in randomised controlled trials.

“As a speciality…we should recognise that although we ourselves might believe that our new technologies are beneficial, if we do not complete randomised controlled trials, other important stakeholders might not believe in these benefits.

Colleagues might not refer patients for the new treatment and payers might not fund it. The best way for us to advance our speciality is to complete more trials such as CHISEL,” they wrote.

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