Title

Response Assessment and Surveillance

Timing

Response assessment timing depends on stage and treatment modality. For LS-SCLC receiving adjuvant systemic therapy ± RT, assessment is recommended only after completion of adjuvant therapy. For LS-SCLC receiving systemic therapy + concurrent RT, assessment after completion of initial therapy. Repeating scans during adjuvant or initial treatment is not recommended in the absence of new symptoms [92]. For systemic therapy alone or sequential therapy, assessment after every 2 cycles of systemic therapy and at completion [92]. For ES-SCLC during systemic therapy, assessment after every 2–3 cycles and at completion. For known brain metastases, brain MRI every 3–4 months or per clinical indication; if systemic therapy given before brain RT, brain imaging repeated every 2 cycles until RT [92].

Response Logic

• For LS-SCLC: after completion of primary treatment, if complete response (CR) or partial response (PR) or stable disease (SD): proceed to surveillance for limited stage. For good PS, consider durvalumab consolidation (category 1) and PCI or MRI brain surveillance. For poor PS, durvalumab alone without PCI recommended. For extensive stage with CR/PR/SD: continue maintenance immunotherapy if started on chemoimmunotherapy; consider MRI brain surveillance ± PCI; consider thoracic RT for selected patients [92].

• For primary progressive disease (PPD): proceed to subsequent therapy/palliative therapy pathway [24].

• For subsequent therapy: continue until progression or unacceptable toxicity. For CNS progression only, continue systemic therapy and treat brain metastases with RT [24].

Imaging Recommendations

• Response assessment imaging: For limited stage, C/A/P CT with contrast and brain MRI (preferred) or brain CT with contrast after completion of adjuvant therapy or initial therapy [92].

• For extensive stage, C/A/P CT with contrast after every 2–3 cycles of systemic therapy and at completion. Brain MRI or CT with contrast every 3–4 months for known brain metastases [92].

• Surveillance after completion of initial therapy: For limited stage, oncology follow-up visits every 3 months during years 1–2, every 6 months during year 3, then annually. For extensive stage, every 2 months during year 1, every 3–4 months during years 2–3, every 6 months during years 4–5, then annually [92].

• Surveillance imaging: CT chest ± abdomen/pelvis every 2–6 months (more frequently in years 1–2, less frequently thereafter). Brain MRI or CT with contrast every 3–4 months during year 1, then every 6 months in year 2, then as clinically indicated, regardless of PCI status [92].

• New pulmonary nodule should initiate workup for potential new primary lung cancer [92].

• FDG-PET/CT is not recommended for routine follow-up unless contrast CT or MRI is contraindicated [92].

• Blood work (CBC, electrolytes, LFTs, BUN, creatinine) as clinically indicated [92].

Biopsy Or Salvage Logic

• For progressive disease, consider biomarker testing if not previously done to determine clinical trial eligibility [24].

• For CNS progression only, continue systemic therapy and treat brain metastases with RT; do not discontinue systemic therapy unless extracranial progression also [24].

• Salvage therapy options: subsequent systemic therapy as per algorithm for PS 0–2; palliative symptom management for PS 3–4. Consider re-treatment with platinum-based regimen if prolonged disease-free time. Tarlatamab-dlle is a category 1 preferred option for subsequent therapy after platinum-based chemotherapy [24,29].

• For transformed SCLC from NSCLC, consider referral to a center with expertise; use SCLC-type chemotherapy; avoid ICIs if TKI is continued [31].