Impact of the SIRFLOX Study on CRC Management

The phase III SIRFLOX study evaluated whether the addition of selective internal radiation therapy (SIRT) to standard chemotherapy in patients with liver metastatic colorectal cancer (CRC) is more effective than chemotherapy alone. The primary endpoint of progression-free survival (PFS) was not improved with the addition of SIRT, states Dirk Arnold, MD. However, liver-specific PFS was markedly improved from 12.6 months with chemotherapy alone to 20.5 months with SIRT (HR = 0.69; P = .002).

The clinical meaningfulness of these findings is still unknown, says Arnold, and it is too early for these analyses to be considered for everyday practice at this time. However, Arnold is optimistic that longer follow up will translate to a larger overall survival (OS) benefit, which is a more relevant endpoint. OS with the addition of SIRT will be assessed from a combined analysis of SIRFLOX and the phase III FOXFIRE and FOXFIRE Global trials.

The SIRFLOX results have strengthened the notion that patients who have a response to the best systemic treatment should then be treated with the best ablative strategy, says Arnold. However, the time point for SIRT use in SIRFLOX is too early, Arnold suggests. This approach could be more effective as a consolidation therapy for patients with widespread, liver limited disease.