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Radiotherapy to the chest after chemotherapy for widespread small-cell lung cancer missed its main target but tripled two-year survival, which is why it is still offered.
Most patients with extensive-stage small-cell lung cancer who respond to chemotherapy still have disease in the chest, and it is usually where they relapse. CREST randomised 495 such patients at 42 hospitals in the Netherlands, the United Kingdom, Norway and Belgium between February 2009 and December 2012 to thoracic radiotherapy, 30 Gy in ten fractions, or to none; all received prophylactic cranial irradiation. The mean interval from diagnosis to randomisation was 17 weeks.
The primary endpoint, one-year overall survival, was not met: 33 percent (95 percent confidence interval 27 to 39) with thoracic radiotherapy against 28 percent (22 to 34), hazard ratio 0.84 (0.69 to 1.01, p=0.066). In a secondary analysis, two-year overall survival was 13 percent against 3 percent (p=0.004), and progression was less likely with radiotherapy (hazard ratio 0.73, 0.61 to 0.87, p=0.001), with six-month progression-free survival 24 against 7 percent. No severe toxic effects were recorded; the commonest grade 3 or worse events were fatigue and breathlessness, in single figures.
CREST is the reason consolidation thoracic radiotherapy is offered to patients with residual thoracic disease after chemotherapy, and the reason it is offered as a discussion rather than as a rule: the trial predates the addition of atezolizumab and durvalumab to first-line chemotherapy, and whether the benefit survives alongside immunotherapy is being tested now.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
495 analysed.
Shares EORTC 08993 (Slotman): prophylactic cranial irradiation in extensive-stage small-cell lung cancer, Extensive-stage small-cell lung cancer, Lung cancer (all types), IMRT / IGRT (modern external beam).
Shares Palliative, Hypofractionated radiotherapy, Lung cancer (all types).
Shares EORTC 08993 (Slotman): prophylactic cranial irradiation in extensive-stage small-cell lung cancer, Lung cancer (all types).
Shares IMpower133, Lung cancer (all types).
Shares IMpower133, CASPIAN, Extensive-stage small-cell lung cancer, Lung cancer (all types).
Shares Palliative, Extensive-stage small-cell lung cancer, Lung cancer (all types).
Shares IMpower133, CASPIAN, Extensive-stage small-cell lung cancer, Lung cancer (all types).
Shares IMpower133, CASPIAN.