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Prognostic Scoring System for Pulmonary Metastasectomy in Colorectal Cancer: External Validation and Clinical Implications for Adjuvant Chemotherapy
by
, , , , ,
Hikaru Takahashi
1, 
Yoshikane Yamauchi
1,*
,
Tomoki Nishida
1,
Masahiro Yanagiya
2,
Hiroshi Hashimoto
3,
Mingyon Mun
4,
Yoko Azuma
5,
Takekazu Iwata
6,
Makoto Endo
7,
Tomohiko Iida
8,
Haruhisa Matsuguma
9,
Takahiko Oyama
10,
Takashi Ohtsuka
11 and
Yukinori Sakao
1 1
Department of Surgery, Teikyo University School of Medicine, Tokyo 173-8605, Japan
2
Department of Thoracic Surgery, The University of Tokyo Graduate School of Medicine, Tokyo 113-8655, Japan
3
Department of Thoracic Surgery, National Defense Medical College, Tokorozawa 359-8513, Japan
4
Department of Thoracic Surgical Oncology, The Cancer Institute Hospital, Tokyo 135-8550, Japan
5
Division of Chest Surgery, Department of Surgery, Toho University School of Medicine, Tokyo 143-8541, Japan
6
Division of Thoracic Surgery, Chiba Cancer Center, Chiba 260-8717, Japan
7
Department of Thoracic Surgery, Yamagata Prefectural Central Hospital, Yamagata 990-2292, Japan
8
Department of Thoracic Surgery, Kimitsu Central Hospital, Kimitsu 292-8535, Japan
9
Division of Thoracic Surgery, Tochigi Cancer Center, Utsunomiya 320-0834, Japan
10
Department of General Thoracic Surgery, National Hospital Organization Tokyo Medical Center, Tokyo 152-8902, Japan
11
Division of Thoracic Surgery, Department of Surgery, Jikei University School of Medicine, Tokyo 105-8471, Japan
*
Author to whom correspondence should be addressed.
Cancers 2026, 18(13), 2072; https://doi.org/10.3390/cancers18132072 (registering DOI)
Submission received: 26 May 2026
/
Revised: 20 June 2026
/
Accepted: 23 June 2026
/
Published: 25 June 2026
(This article belongs to the Special Issue Contemporary Thoracic Cancer Surgery: Technology and Innovation)
Simple Summary
Predicting outcomes after pulmonary metastasectomy for colorectal cancer remains challenging, as existing prognostic factors lack the precision required for optimal patient selection. This study developed and validated a novel prognostic scoring system based on a landmark meta-analysis to improve risk stratification and guide post-operative chemotherapy decisions. The resulting system effectively categorized patients into three distinct risk groups. Our retrospective analysis highlights that routine chemotherapy may not benefit low-risk patients and was associated with earlier recurrence. Additionally, survival benefits in high-risk patients were not accompanied by improved recurrence-free survival, suggesting they may be attributable to patient selection rather than a direct treatment effect. These findings provide a practical, evidence-based framework for individualized surgical decisions and may significantly influence the design of future clinical trials by addressing selection biases in treatment efficacy.
Abstract
Background: Predicting long-term outcomes after pulmonary metastasectomy for colorectal cancer remains challenging because existing prognostic methods lack precision. We developed and validated a prognostic scoring system derived from a major international meta-analysis to improve risk stratification and to evaluate the benefit of adjuvant chemotherapy across risk groups. Methods: Using a Japanese registry of 819 patients who underwent lung resection between 2010 and 2019, we constructed a 0–13-point score based on eight variables including tumor size, number, biological markers, and intrathoracic lymph node status, which may require intraoperative or pathological confirmation. Granular data on chemotherapy regimens, timing, and duration were unavailable. Patients were classified as low, intermediate, or high risk. The primary analysis used inverse probability of treatment weighting to adjust for baseline imbalances; however, only 819 of 1657 patients (49.4%) had complete prognostic data, introducing potential selection bias. Results: The score separated patients into three groups with distinct five-year survival rates: 81.1% (low), 67.8% (intermediate), and 59.1% (high). In high-risk patients, chemotherapy was associated with improved overall survival but did not delay recurrence. In low-risk patients, chemotherapy correlated with reduced recurrence-free survival, a finding that persisted after adjustment. Conclusions: This validated scoring system aids individualized surgical decision making by identifying patients unlikely to benefit from routine postoperative chemotherapy. Observed survival advantages in high-risk patients may reflect selection of fitter individuals rather than direct treatment effects, underscoring the need to address selection bias in future trials.
