- Perineural invasion (PNI) is an indicator of better distant failure-free survival (DFFS) with adjuvant chemotherapy (ACT) among patients with stage II-III rectal cancer who have undergone long-course preoperative chemoradiotherapy (CRT) followed by total mesorectal excision (TME).
- There was no significant DFFS benefit for ACT among patients with lymphovascular invasion (LVI).
Why this matters
- ACT is routinely used after TME, but previous studies have failed to establish a benefit, leading to uncertainties about patient selection.
- Retrospective analysis of 1232 patients treated at 6 tertiary institutions in Korea (median age, 62 years; 31.8% women; 75.6% clinical N stage positive).
- Funding: None.
- 15.0% of patients had LVI, 17.1% had PNI, 6.5% had both, and 74.3% had neither.
- 5-year OS, recurrence-free survival, and DFFS were highest in the group with no PNI or LVI (89.1%, 78.7%, and 84.6%, respectively), followed by LVI only (77.9%, 58.7%, 61.4%), PNI only (67.6%, 44.6%, 54.2%), and both (56.2%, 38.6%, 48.6%; P<.001 for all>
- Adjuvant chemotherapy was associated with improved 5-year DFFS in patients with PNI (44.9% vs 54.6%; P=.048), but not patients with LVI.
- Retrospective analysis.
- Korean cohort.