*8.3. Co-Administration of Steroids*

Tumor-bearing patients often receive steroids as symptomatic treatment for worsening systemic symptoms and symptoms due to cancer progression. In general, steroids are routinely administered as antiemetics during platinum-based chemotherapy. However, steroids may reduce the effects of ICIs by suppressing immune responses induced by IL-2 and CD8-positive T cells [56,57], and increasing Tregs [58,59].

Ricciuti et al. reported that patients receiving PSL-equivalent steroids at ≥10 mg on the initiation of ICI therapy had a significantly shorter survival (PFS 2.0 mo vs. 3.4 mo, HR 1.3; OS 4.9 mo vs. 11.2 mo, HR 1.7) than those receiving ICI-equivalent steroids at ≤10 mg [60]. On the contrary, the use of steroids for therapeutic purposes to counter irAE occurring during ICI treatment does not impair the efficacy of ICI [61,62]. Thus, co-administration of steroids during ICI therapy remains a future challenge for lung cancer treatment.
