V22: Conditional Survival After Total Neoadjuvant vs Standard Neoadjuvant Chemoradiation in Patients with Locally Advanced Rectal Cancer

Conditional survival (CS) is the probability of surviving additional years after a given interval from curative treatment. According to NCCN guidelines, both neoadjuvant chemoradiation (nCRT) with multi-agent adjuvant chemotherapy and total neoadjuvant chemoradiation (TNT) are acceptable regimens for the treatment of locally advanced rectal cancer (LARC). Nonetheless, a perceived advantage of TNT is that early treatment of micrometastases could theoretically decrease the risk of subsequent distant disease. However, there is a paucity of long-term data on the comparative effectiveness of nCRT and TNT on overall survival (OS). Since prognosis 3 years post treatment is likely related to metastatic disease, we hypothesized that TNT would be associated with higher rates of CS.

 


Methods: The National Cancer Database (2010-2017) was queried for adult patients with stage II-III rectal cancer who underwent proctectomy with negative margins and received neoadjuvant chemoradiation. CS was investigated at 3 years.


Results:

Of the initial cohort of 10,777 patients, 8020 survived at least 3 years after the diagnosis. The majority of patients were Caucasian, had no comorbidities, and were aged < 70 years; 37% had stage II disease, while 63% had stage III disease. The 5-year OS was 84% for the initial cohort, while for those with a CS of 3 years, OS was 91%. Sixty-five percent of patients underwent nCRT, while 35% received TNT. Rates of sphincter preserving surgeries did not differ for both groups. After adjustment for available confounders, age ≥70, male sex, public health insurance, Chalson-Deyo score, and abdominoperineal resection (APR) were associated with worse overall survival (p< 0.01). Increasing doses of radiation and perioperative treatment (TNT vs nCRT) did not have an impact on CS (Figure 1).


Conclusions:

In this national cohort of LARC patients , we confirmed known clinicodemographic factors, including older age, male gender, comorbidities, and undergoing APR, to be associated with lower survival. However, neoadjuvant regimen was not associated with 3-year CS, suggesting that TNT might not impact the subsequent development of distant disease.