Regrowth Predicts Metastasis in Rectal Cancer Watch and Wait

TOPLINE:

Tumor regrowth predicts distant metastases in patients with rectal cancer undergoing surveillance after complete clinical responses to neoadjuvant therapy.

METHODOLOGY:

• “Watch and wait” is generally offered to patients with rectal cancer who have a complete clinical response to neoadjuvant therapy.
• Up to 30% of tumors regrow within 3 years, and about 5% of patients develop distant metastases.
• To get a better handle on the risk factors, investigators identified 508 watch-and-wait patients from the International Watch & Wait database who had a local regrowth and underwent resection.
• The team compared them with 893 patients from a Spanish registry who had total mesorectal excisions after neoadjuvant therapy and who were found to have had a nearly complete response to neoadjuvant therapy, meaning that 90% or more of their tumor was gone.

TAKEAWAY:

• Three-year distant metastasis–free survival was 75% in the watch-and-wait/regrowth group vs 87% in the upfront surgery arm (P = .001); the results held when the two groups were stratified by pathological T stage and nodal status.
• Patients with local regrowth also had a higher risk of developing distant metastasis (22.8% vs 10.2% at 3 years).
• Local regrowth was an independent risk factor for distant metastasis, along with higher pathological T stage and positive nodal status on the resected regrowth specimen.
• Baseline clinical T stage and nodal status were not significantly associated with risk.

IN PRACTICE:

“Leaving the primary undetectable tumor in situ until development of local regrowth may result in worse oncological outcomes ... Efforts should be made to minimize the risk of local regrowth among patients undergoing watch and wait by the use of very stringent criteria for the identification of a clinical complete response.” There may be a role for ctDNA to improve patient selection for watch and wait.

SOURCE:

The study was led by Laura Melina Fernandez of the Champalimaud Foundation in Lisbon, Portugal, and presented on January 20, 2024, at the ASCO Gastrointestinal Cancers Symposium.

LIMITATIONS:

The definition of “complete clinical response” and selection of patients for watch and wait varied across International Watch & Wait database institutions. Recruitment occurred before implementation of total neoadjuvant therapy regimens.

DISCLOSURES:

There was no external funding for the work. The lead investigator didn’t have any disclosures.

A version of this article appeared on Medscape.com.