The course of lung oligometastatic colorectal cancer may be a reflection of selection for treatment rather than an effect of stereotactic body radiotherapy

Excerpt

Nicosia et al. have provided a detailed report of their retrospective observational study of use of stereotactic radiotherapy (SBRT) in patients with ‘oligometastatic’ colorectal cancer (CRC) [1]. Unfortunately, the results presented make it hard to justify their optimistic conclusion that it ‘combines high local control rates with a favourable impact on survival outcomes’. The primary outcome of the study—‘time to polymetastatic disease’—has neither biological meaning nor clinical relevance. The distribution of the number of metastases in patients with stage IV CRC is almost certainly continuous and so their choice of greater than five metastases as the definition of ‘polymetastatic’ disease is entirely arbitrary. ‘Oligometastatic’ disease has no agreed definition and is a condition determined by therapeutic opportunity rather than tumour biology [2]. …