What To Do With Suspected Nodal Regrowth on Magnetic Resonance Imaging During Follow-up in an Organ Preservation Approach for Rectal Cancer?

Background: For nodal regrowth in patients with rectal cancer following watch-and-wait standardized protocols on diagnostic procedures and subsequent treatment are lacking.

Objective: Evaluate the diagnosis and treatment of suspected nodal regrowth following an organ preservation approach.

Settings: Patients were included from national and institutional watch-and-wait -databases.

Design: Thirty-five rectal cancer patients with suspected nodal regrowth on magnetic resonance imaging were retrospectively identified during watch-and-wait follow-up.

Patients: Twenty-seven of 35 patients followed watch-and-wait after neoadjuvant (chemo)radiotherapy and 8/35 followed watch-and-wait schedule after local excision for early rectal cancer.

Main Outcome Measures: Diagnostic procedures, treatment and histopathological outcome.

Results: Median follow-up was 34 months. Median time from end of (chemo)radiotherapy or local excision to first detection of suspected nodal regrowth on magnetic resonance imaging following watch-and-wait was 9 and 10 months. After first detection, 17 of 35 patients underwent immediate treatment without further diagnostics, of whom 7 also had luminal regrowth. In 18 of 35 patients, additional diagnostic procedures were performed. In 4 of 18 patients, positron emission tomography-computed tomography or endorectal ultrasound-guided biopsy was performed and treatment was initiated based on increased nodal regrowth suspicion. In 14 of 18 patients, MRI was repeated after 8-12 weeks: growth of suspected lymph nodes was the most decisive factor to proceed to treatment. In 8 patients, repeated magnetic resonance imaging was combined with positron emission tomography-computed tomography and/or endorectal ultrasound-guided biopsy: in half of them it contributed to treatment initiation. In total, 34/35 patients were treated: 9 received (re-)irradiation and 33 underwent total mesorectal excision. In 27 of 33 patients, nodal regrowth was pathologically confirmed in the total mesorectal excision-resection specimen; 5 of 6 patients without nodal involvement had pathologically confirmed luminal regrowth.

Limitations: Highly selected study population.

Conclusions: During watch-and-wait follow-up of patients with rectal cancer in an organ preservation strategy, magnetic resonance imaging plays an important role in diagnosis of nodal regrowth. Repeated magnetic resonance imaging after an interval can be helpful in making treatment decisions, and the role of positron emission tomography-computed tomography and endorectal ultrasound-guided biopsy appears limited. See Video Abstract.