Recurrence Risk After Resection of Typical and Atypical Pulmonary Carcinoids: A Systematic Review and Meta-Analysis

Pulmonary carcinoids generally have favorable outcomes after surgery, but postoperative recurrence differs substantially by histological subtype. Existing guidance recognizes atypical histology and nodal involvement as adverse features, yet a focused quantitative synthesis of the magnitude and consistency of this association remains limited.

MEDLINE/PubMed, Scopus, and Embase were searched from inception to July 12, 2026 for surgical cohorts reporting postoperative recurrence. Two reviewers independently screened titles and abstracts and assessed full-text eligibility, with disagreements resolved by consensus. The primary meta-analysis emphasized the risk ratio (RR) of observed recurrence in atypical versus typical carcinoids using random-effects models with restricted maximum likelihood and modified Hartung-Knapp intervals; odds ratios (ORs) and risk differences were complementary measures. Time-defined recurrence, adjusted prognostic factors, and anatomical patterns were synthesized separately because of incompatible outcome definitions and effect measures.

Eighteen reports were included in the review, 11 contributed structured quantitative evidence, and 7 independent comparative cohorts entered the primary meta-analysis. Among 1074 resected tumors, recurrence occurred in 24 of 816 typical carcinoids and 51 of 258 atypical carcinoids. The pooled RR of observed recurrence was 6.57 (95% CI, 3.65-11.84), with a complementary OR of 8.08 (95% CI, 4.20-15.53). No statistical heterogeneity was detected (I² = 0%), but this result was interpreted cautiously because only seven studies were available and clinically important differences in follow-up, staging, pathological review, and surveillance remained. Leave-one-out RR estimates ranged from 5.77 to 7.48. Time-defined evidence suggested recurrence of approximately 18%-25% by 5 years and 29%-32% by 10 years in atypical tumors, whereas node-negative typical tumors generally remained below 5% at 10 years, although late events occurred. Nodal involvement, advanced pT category, and larger tumor size were adverse prognostic features.

Observed recurrence after resection was substantially more frequent in atypical than in typical pulmonary carcinoids. Histology and nodal status provide a clinically useful basis for postoperative risk stratification, but the available evidence does not establish the optimal surveillance modality, interval, or duration.