Evaluation of the prognostic impact of intraoperative cytology results according to tumor sidedness in stage II/III resectable colorectal cancer.

Authors

Akihiro Usui, Hirotoshi Kobayashi, Kenjiro Kotake, Kotaro Maeda, Takeshi Shuto, Masayasu Kawasaki, Koji Komori, Heita Ozawa, Chihiro Kosugi, Masayuki Ohue, Kimihiko Funahashi, Ichiro Takemasa, Hideyuki Ishida, Shinsuke Kazama, Yoshifumi Shimada, Hajime Motohashi, Yusuke Kinugasa, Yukihide Kanemitsu, Hiroki Ochiai, Soichiro Ishihara, Michio Itabashi, Kenichi Sugihara, Hideki Ueno

Published in

International journal of colorectal disease. Jun 15, 2026. Epub Jun 15, 2026.

Abstract

To investigate whether colorectal cancer (CRC) sidedness is associated with intraoperative lavage cytology results, tumor recurrence, and prognosis.
Using data from a multicenter prospective observational study conducted by the Japanese Society for Cancer of the Colon and Rectum (JSCCR), we retrospectively analyzed prognosis and recurrence patterns in pathological stage II/III right-sided and left-sided CRC, stratified by positive versus negative lavage cytology results.
A total of 1500 patients met the inclusion criteria and were enrolled. Of these, 534 had right-sided CRC and 966 had left-sided CRC. Fifty-nine patients (3.9%) had positive lavage cytology. Among patients with recurrence, pT4, positive lavage cytology, and right-sided tumor location were independently associated with peritoneal recurrence. Among cytology-negative patients, the 5-year relapse-free survival (RFS) rate was significantly higher in right-sided than in left-sided CRC (79.6% vs. 73.4%, p = 0.01), whereas the 5-year overall survival (OS) rate did not differ significantly (89.2% vs. 87.7%, p = 0.52). Among cytology-positive patients, no statistically significant differences in RFS or OS were observed between tumor locations. However, among cytology-positive patients who developed recurrence, post-recurrence survival was significantly worse in right-sided CRC than in left-sided CRC (p = 0.04).
Among cytology-negative patients, left-sided CRC was associated with poorer RFS than right-sided CRC, although OS did not differ. Right-sided tumor location and positive lavage cytology were independently associated with peritoneal recurrence among patients who developed recurrence. Among cytology-positive patients, right-sided CRC was associated with poorer post-recurrence survival.

PMID:
42298064
Bibliographic data and abstract were imported from PubMed on 16 Jun 2026.

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