Stage II and III rectal adenocarcinoma outcomes related to lymphovascular invasion.

Abstract

698 Background: Lymphovascular invasion (LVI) has been shown to be associated with nodal involvement and higher rates of local recurrence in rectal cancer. In some studies, the presence of LVI has also been associated with worse overall survival; however, these have been mostly smaller, single institution studies or incomplete data sets. Our goal was to examine the effect of LVI on prognosis in a large and inclusive database. Methods: Outcomes of patients with clinical stage II and stage III rectal adenocarcinoma in the National Cancer Data Base (NCDB) from 2011 to 2015, in whom LVI data was available, were included. Exclusion criteria incorporated patients who did not receive neoadjuvant radiation and chemotherapy, neoadjuvant or adjuvant. Overall survival was compared in patients with and without LVI, controlling for age, sex, race, comorbidities, socioeconomic factors, and T and N stages using Kaplan-Meier survival curves and Cox proportional hazards regression analysis. Median overall survival and hazard ratios with 95% confidence intervals are reported where available. Results: The dataset included 9206 patients with stage II and 12640 patients with stage III rectal adenocarcinoma for which LVI data were available and who received the study’s previously defined standard of care. The proportion of patients with LVI was 11% in stage II and 16% in stage III rectal cancer. After adjusting for age, sex, race, T or N stage, and other clinical and demographic variables, LVI was associated with worse overall survival in stage II HR 1.87 (1.62-2.16, p < 0.001) and in stage III HR 1.8 (1.61-2.02, p < 0.001) rectal cancer. The median overall survival was not reached in stage II rectal cancer patients without LVI versus 5.73 years with LVI. In stage III rectal cancer, the median overall survival was 6.91 years without LVI versus 6.21 years with LVI. Conclusions: Lymphovascular invasion is an independent risk factor of mortality in stage II and III rectal cancer. Stage II rectal cancer patients without LVI have comparatively good survival of the groups studied, potentially identifying a group of patients that may benefit from de-escalated therapy. Further studies will be guided at identifying if benefits with chemotherapy are associated with LVI status.