Intrathoracic radiotherapy shows potential in extensive-stage SCLC

By Afsaneh Gray, medwireNews Reporter

A phase III randomised controlled trial shows that intrathoracic radiotherapy after chemotherapy significantly reduces the chances of disease progression in patients with extensive-stage small-cell lung cancer (ES-SCLC).

The trial researchers therefore believe that “[t]horacic radiotherapy in addition to prophylactic cranial irradiation should be considered for all patients with ES-SCLC who respond to chemotherapy.”

Survival remains poor for patients with ES-SCLC, and intrathoracic tumour control is a major challenge. However, there is some evidence that thoracic radiotherapy may improve local control and survival, although the level of evidence has, until now, been low.

Lead author Ben Slotman (VU University Medical Center, Amsterdam, the Netherlands) and colleagues enrolled a total of 498 patients from across 42 hospitals in Europe and randomly assigned them to receive prophylactic cranial irradiation plus thoracic radiotherapy (up to a dose of 30 Gy in 10 fractions) or cranial irradiation alone. Three patients subsequently withdrew consent, leaving 247 patients in the thoracic radiotherapy group and 248 controls.

All participants had confirmed ES-SCLC that responded to chemotherapy with platinum-based agents and World Health Organization performance scores of 0 to 2. The primary endpoint was overall survival at 1 year; secondary endpoints included progression-free survival.

The mean interval between diagnosis and randomisation was 17 weeks, and median follow-up was 24 months.

At 1 year, overall survival was 33% for the thoracic radiotherapy group and 28% for the control group, a nonsignificant difference. However, a secondary analysis revealed that at 2 years the difference in overall survival between the two groups was significant and in favour of thoracic radiotherapy, at 13% versus 3%.

Furthermore, disease progression was significantly less likely in the thoracic radiotherapy group compared with controls (hazard ratio=0.73). At 6 months, progression-free survival in those who had received thoracic radiotherapy was 24% compared with 7% in the control group.

Writing in The Lancet, the authors point out that “[t]horacic radiotherapy was well tolerated and we recorded no severe acute or late toxic effects.” Given this, they suggest that further studies could assess higher doses of radiation.

For the present, they recommend that this treatment be considered in ES-SCLC patients who have responded to chemotherapy.

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