KEY POINTS
- The report describes 2 patients with limited-stage SCLC who underwent memory-avoidance prophylactic cranial irradiation after a favorable response to definitive thoracic chemoradiotherapy.
- Rather than avoiding only the hippocampi, planning spared the bilateral hippocampi, amygdalae, fornix and corpus callosum, each incorporated into a memory-avoidance region with a 5-mm planning risk volume expansion.
- Both patients received 25 Gy in 10 fractions using VMAT, with concurrent memantine planned for 6 months. Whole-brain coverage was maintained: PTV V25 Gy was 95% in both cases, with D98% of 23.88 and 23.30 Gy.
- Dose to the combined memory-avoidance region was substantially reduced. D100% was 6.31 and 6.53 Gy, while D0.03cc was 16.37 and 15.59 Gy in the two patients. Similar sparing was achieved individually for the hippocampi, fornix, amygdalae and corpus callosum.
- Both patients completed treatment without interruption or significant acute toxicity, and PROMIS cognitive function scores remained stable during available follow-up.
- Neither patient developed intracranial recurrence during reported surveillance. One patient remained intracranially controlled at ongoing follow-up; the second died from extracranial disease progression 7 months after PCI without brain metastases.
- The evidence is extremely preliminary: there were only two patients, no standardized prospective neuropsychological testing, immature follow-up and no comparison with conventional or hippocampal-avoidance PCI. Dosimetric feasibility does not establish cognitive benefit.
CLINICAL TAKEAWAY
Sparing memory-related structures beyond the hippocampi appears technically achievable without sacrificing PCI target coverage. The concept is biologically interesting, but this is essentially a two-patient feasibility report; there is currently no evidence that memory-network avoidance preserves cognition better than hippocampal avoidance alone.