QS129 - Local Regrowths and the Risk of Distant Metastases – It Is Not a Question of Time

Sunday, June 2, 2024

1:36 PM – 1:39 PM ET, USA

Location: Room 327

Quick Shot Presenter(s)

Rodrigo O. Perez, MD, PhD

Chair Colorectal surgery division
Hospital alemão Oswaldo Cruz
Hospital Alemão Oswaldo Cruz
Sao paulo, Sao Paulo, Brazil

Disclosure information not submitted.

Author(s)

Laura Melina Fernandez, MD (she/her/hers)

Colorectal surgeon
Champalimaud Foundation
Lisbon, Lisboa, Portugal

All relevant financial disclosures have been managed and will be listed below.
This individual has no financial relationships with ineligible companies.

Author(s)

Bruna B. Vailati, MD (she/her/hers)

Colorectal Surgeon
A&J Gama Institute
Instituto Angelita & Joaquim Gama
Sao Paulo, Sao Paulo, Brazil

All relevant financial disclosures have been managed and will be listed below.
This individual has no relevant relationships with ineligible companies.

Author(s)

GS

Guilherme P. São Julião, MD, n/a

Colorectal Surgeon at Hospital Alemão Oswaldo Cruz and Hospital BP
Colorectal Surgeon at Hospital Alemão Oswaldo Cruz and Hospital BP
São Paulo, Sao Paulo, Brazil

Disclosure information not submitted.
LC

Leonardo Ervolino Corbi, n/a

Surgeon
Hospital Alemão Oswaldo Cruz
São Paulo, Sao Paulo, Brazil

Disclosure information not submitted.
AH

Angelita Habr-Gama, PhD

professor of surgery
Angelita and Joaquim Gama Institute, Sao Paulo, Brazil Colorectal Surgery Division, University of São Paulo School of Medicine, Sao Paulo, Brazil
São Paulo, Sao Paulo, Brazil

Disclosure information not submitted.
JA

Jose Azevedo, MD

Surgeon
Champalimaud Foundation
Lisboa, Lisboa, Portugal

Disclosure information not submitted.
AP

Amjad Parvaiz, MD FRCS

Chief Colorectal surgery Department Director of European Academy of robotic colorectal surgery
Champalimaud foundation Lisbon
Lisbon, Lisboa, Portugal

Disclosure information not submitted.
QD

Quentin Denost, 14CY04352

Professor MD PhD
Bordeaux Colorectal Institute, Clinique Tivoli-Ducos, Bordeaux, France.
BORDEAUX, Aquitaine, France

Disclosure information not submitted.

Purpose/Background: Local regrowths (LR) are incomplete responses to nCRT that are mistaken for “apparent” complete clinical responses. These patients are at increased risk for the subsequent development of distant metastases (DM). The presence of microscopic undetectable residual rectal cancer left in situ for a significant amount of time could have contributed to this increased risk for DM. To examine the role of time elapsed between completion of nCRT to definitive surgical resection of the primary/regrowth in development of DM, we reviewed the outcomes of patients with excellent response to nCRT managed by primary resection at different time intervals from the end of radiation.

Methods/Interventions: Consecutive patients from 3 different Institutions between September 1993 and April 2020 with non-metastatic rectal cancer located ≤7cm from the anal verge and underwent nCRT were reviewed. Excellent response was defined as: (1) complete clinical response managed by Watch and Wait followed by a LR or (2) near-complete pathological response (≤10% residual cancer cells) managed by TME at the time of reassessment of response to nCRT. Time to resection of the primary was defined as the time elapsed between the end (last day) of radiation and final surgical resection of the primary. The hypothesis is that time elapsed between completion of RT and definitive surgery of the primary/regrowth is associated with the risk of subsequent distant metastases.

Results/Outcomes: Overall, 93 patients who achieved initial cCR followed by LR were included and compared with 72 patients who underwent TME after nCRT with the finding of a near-complete pathological response in the specimen. Overall, 34 patients developed DM. Of these, 8 patients in the TME at reassessment group and 26 patients in the LR group. The mean interval for the development of DM was 11.5 and 25.4 months for TME at reassessment and LR respectively. Time to resection of the primary was similar between patients with and without DM development (7.8 wks vs 8.0 wks respectively; p=0.79). Within patients with LR, time to resection of the primary was also not significantly different between patients who did and who did not develop DM (14.4 versus 17.9 months; p=0.26). A ROC-curve was created search for a potential critical cutoff time. Curves using the entire cohort or only patients with LR showed disappointing areas under the curve (AUC=0.59 p=0.10; AUC=0.42 p=0.27, respectively) suggesting a similar decrease in specificity for every increase in sensitivity of time to resection as a predictor/risk factor of DM.

Conclusion/Discussion: In conclusion, time to resection of the primary cancer, reflecting time elapsed from RT completion until development of LR with the residual cancer in situ, is not a risk factor for subsequent development of DM. Other features may be responsible for the increased risk of DM among these patients. Longer intervals with microscopic residual cancer in situ are not the sole differences between LR and near-complete pathological responses to justify the significant differences in the development of DM.