Integrated prognostic model of perineural invasion and lymph node ratio for survival prediction in stage III rectal cancer.

BACKGROUND

Stage III rectal cancer prognosis remains challenging despite therapeutic advances. This study investigates the combined prognostic value of perineural invasion and lymph node ratio, 2 established markers that have not been studied synergistically.

METHODS

Retrospective analysis of 3,881 patients from the Surveillance, Epidemiology, and End Results database (training cohort) and 498 patients from 2 Chinese hospitals (validation cohort). Cox regression identified prognostic factors, and a subsequent nomogram was developed for 3-/5-year cancer-specific survival.

RESULTS

Perineural invasion-positive patients showed significantly lower 3-year (74.7% vs 86.7%) and 5-year cancer-specific survival (61.7% vs 76.0%) than perineural invasion-negative counterparts (P < .0001). Lymph node ratio stratification revealed that perineural invasion had a stronger prognostic impact in the lymph node ratio ≤0.5 subgroups. The integrated nomogram incorporating perineural invasion, lymph node ratio, tumor grade, carcinoembryonic antigen status, and treatment parameters demonstrated high accuracy (area under the curve, 0.764-0.839) with excellent calibration.

CONCLUSION

Perineural invasion and lymph node ratio synergistically predict survival in stage III rectal cancer. The validated nomogram provides a practical tool for individualized prognosis assessment and therapeutic decision-making, addressing current gaps in risk stratification.