EP366 - Real-world Survival Outcomes in Locally Recurrent Rectal Cancer: A Japanese Multicenter Study of 2,266 Cases

Sunday, May 10, 2026

1:02 PM - 1:07 PM ET

ePoster Presenter(s)

Kay UEHARA, MD, PhD

Associate Professor
Nippon Medical School Hospital
Nippon Medical School Hospital
Tokyo, Tokyo, Japan

Disclosure information not submitted.

Author(s)

MS

Masanori Sando, MD, PhD

Staff Surgeon, Department of Colorectal Surgery
Department of Colorectal Surgery, National Cancer Center Hospital East, Kashiwa, Japan
Kashiwa, Chiba, Japan

Disclosure information not submitted.
HT

Hirotoshi Takiyama, n/a

Radiation Oncologist
QST Hospital
Chiba, Chiba, Japan

Disclosure information not submitted.
MU

Mamoru Uemura, MD, PhD

Associate Professor
Osaka University
Suita City, Osaka, Japan

Disclosure information not submitted.
YT

Yuichiro Tsukada, MD, PhD

Assistant Chief
National Cancer Center Hospital East
Kashiwa, Chiba, Japan

Disclosure information not submitted.
TM

Toshiki Mukai, Ph.D.

Head surgeon
Dept. colorectal surgery, Cancer Institute Hospital
Koto-Ku, Tokyo, Japan

Disclosure information not submitted.
GT

Goro Takahashi, MD, PhD

Associate Professor
Nippon Medical School
Bunkyo-ku, Tokyo, Japan

Disclosure information not submitted.
KK

Kazushige Kawai, Doctor

Chief
Department of Colorectal Surgery
Bunkyo-ku, Tokyo, Japan

Disclosure information not submitted.
AO

Atsushi Ogura, MD, PhD

Lecture
Nagoya University hosipital
Nagoya, Aichi, Japan

Disclosure information not submitted.
SI

Soichiro Ishihara, Colorectal Surgery

Professor
The University of Tokyo
Bunkyo-ku, Tokyo, Japan

Disclosure information not submitted.
YT

Yuichi Takayama, Board Certified Surgeon in Gastroenterology

Chief Surgeon
Surgery
Ogaki, Gifu, Japan

Disclosure information not submitted.
SM

Shuichiro Matoba, phD

head of colorectal surfery
Toranomon Hospital
Minato-ku, Tokyo, Japan

Disclosure information not submitted.
YS

Yasumitsu Saiki, M.D

Assistant Director
Coloproctology Center Takano Hospital
Kumamoto, Kumamoto, Japan

Disclosure information not submitted.
GO

Gaku Ohira, Gastrointestinal surgeon

assistant professor
Chiba University Graduate School of Medicine
Chiba, Chiba, Japan

Disclosure information not submitted.
RI

Ryo Inada, n/a

medical director
Kochi Health Sciences Center
Kochi, Kochi, Japan

Disclosure information not submitted.
TH

Takahisa Hirokawa, MD, PhD　Board Certified Surgeon (Japan Surgical Society)

Director of Gastroenterological Surgery
Kariya Toyota General Hospital, Aichi, Japan
Kariya, Aichi, Japan

Disclosure information not submitted.
TM

Toshiki Masuishi, MD, PhD

Medical Oncologist, Department of Clinical Oncology
Aichi Cancer Center Hospital
Nagoya, Aichi, Japan

Disclosure information not submitted.
MI

Masataka Ikeda, Japanese Board of Colon and Rectal Surgeons

Professot
Hyogo Medical University
Nishinomiya, Hyogo, Japan

Disclosure information not submitted.
YK

Yukihide Kanemitsu, MD

Chief, Department of Colorectal Surgery
National Cancer Center, Japan
Tokyo, Tokyo, Japan

Disclosure information not submitted.
FK

Fumikazu Koyama, M.D., Ph.D.

Professor
Department of Surgery, Nara Medical University
Kashihara, Nara, Japan

Disclosure information not submitted.
HU

Hideki Ueno, MD, PhD

Professor and Chairman
National Defense Medical College
Tokorozawa, Saitama, Japan

Disclosure information not submitted.
YK

Yoshiki Kajiwara, M.D., Ph.D

Assorciate Professor
National Defense Medical College
Tokorozawa, Saitama, Japan

Disclosure information not submitted.
KH

Koya Hida, Board Certified Surgeon

Associate professor
Kyoto University
Kyoto, Kyoto, Japan

Disclosure information not submitted.
AS

Akio Shiomi, Coloreactal surgeon

Chief
Division of Colon and Rectal Surgery
Nagaizumi, Shizuoka, Japan

Disclosure information not submitted.
TN

Takeshi Naitoh, MD, PhD

Chairman
Department of lower GI surgery, Kitasato University School of Medicine
Yamato, Kanagawa, Japan

Disclosure information not submitted.
MY

Masayoshi Yasui, MD, PhD

Director of Gastroenterological Surgery
Osaka International Cancer Institute
Osaka, Osaka, Japan

Disclosure information not submitted.
FF

Fumihiko Fujita, MD, PhD, FACS

Professor
Department of Surgery, Kurume University
Kurume, Fukuoka, Japan

Disclosure information not submitted.
TM

Takuya Miura, M.D., Ph.D.

Associate Professor
Hirosaki University Graduate School of Medicine
Hirosaki, Aomori, Japan

Disclosure information not submitted.
TK

Takeshi Kato, MD, PhD

Head, Department of Surgery
National Hospital Organization Osaka National Hospital
Osaka, Osaka, Japan

Disclosure information not submitted.
NT

Naoyuki Toyota, n/a

Surgeon-in-chief
Department of Colorectal Surgery, Tochigi Cancer Center
Utsunomiya, Tochigi, Japan

Disclosure information not submitted.
HY

Hideaki YANO, MD, PhD, FRCS

Consultant Colorectal Surgeon
University Hospital Southampton
WINCHESTER, England, United Kingdom

Disclosure information not submitted.
KS

Kenichi Sugihara, Surgeon

Professor
Institute of Science of Tokyo
Kita-ku, Tokyo, Japan

Disclosure information not submitted.
YA

Youichi Ajioka, Ph., MD.

Professor
Division of Molecular and Diagnostic Pathology, Graduate School of Medical and Dental Sciences, Niigata University
Niigata, Niigata, Japan

Disclosure information not submitted.

Purpose/Background: Locally recurrent rectal cancer (LRRC) develops in approximately 5-10% of patients following curative resection and continues to present a significant clinical challenge, with limited high-quality evidence available to guide treatment selection.

Methods/Interventions: This study aimed to evaluate long-term survival outcomes across different treatment modalities for LRRC, using data from the world's largest LRRC database. The study was conducted as a project of the Japanese Society for Cancer of the Colon and Rectum (JSCCR) and included 2,266 patients diagnosed with LRRC between 2011 and 2023 at 76 institutions across Japan. Clinical and pathological data were retrospectively collected from institutional databases and medical records. Patients were categorized based on the initial treatment received: surgery (1,143 cases, 50.4%), particle therapy - of which the vast majority (98.7%) was carbon-ion therapy - 391 cases, 17.3%), radiotherapy (250 cases, 11.0%), chemotherapy alone (367 cases, 16.2%), and palliative care (115 cases, 5.1%). The median follow-up duration was 5.1 years.

Results/Outcomes: The 3-year overall survival (OS) rates were 82.1% for surgery, 83.8% for particle therapy, 53.1% for radiotherapy, 37.8% for chemotherapy alone, and 6.3% for palliative care. No significant difference in OS was observed between surgery and particle therapy (P = 0.873), while all other comparisons revealed statistically significant differences (P < 0.01), indicating that both surgery and particle therapy offered superior survival outcomes. A subgroup analysis was performed for patients with LRRC without distant metastasis, in whom 950 underwent surgery and 379 received particle therapy, nearly all of which (99.5%) was carbon-ion therapy. Among the surgical cases, R0 resection (no residual tumor) was achieved in 81.9%, R1 (microscopic residual tumor) in 15.4%, and R2 (macroscopic residual tumor) in 2.7%. The 3-year and 5-year OS rates were 87.9% and 71.9% for R0 resections, 74.5% and 48.6% for R1 resections, and 84.6% and 60.7% for particle therapy, respectively. All intergroup comparisons showed statistically significant differences (P < 0.01).

Conclusion/Discussion: Both surgery and particle therapy demonstrated favorable long-term outcomes for LRRC, significantly outperforming radiotherapy, chemotherapy alone, and palliative care. Radiotherapy also conferred better survival than chemotherapy alone. Notably, R0 resection was associated with the best prognosis, reinforcing its role as the primary objective of surgical treatment. Importantly, in cases where R0 resection is not feasible, particle therapy appears to offer a promising alternative, achieving outcomes comparable to surgical resection. These findings may inform treatment decision-making and multidisciplinary strategies in the management of LRRC.

OS by treatment modality in patients with LRRC

This figure compares overall survival across five treatment groups: surgical resection, particle therapy, radiotherapy, chemotherapy alone, and palliative care. Surgical resection and particle therapy showed comparable outcomes (P = 0.873), while all other comparisons were statistically significant (P < 0.001).
OS in patients with LRRC without distant metastasis: R0 surgical resection vs. particle therapy

R0 resection was associated with significantly better survival than particle therapy (P = 0.003). All other comparisons also demonstrated significant differences (P < 0.001).