Patterns of failure and implications for clinical target volume definition of locally advanced T4b rectal cancer identified with magnetic resonance imaging and treated using neoadjuvant chemoradiotherapy and surgery.

BACKGROUND AND PURPOSE: Elective irradiation of the external iliac lymph nodes (EIN) has always been advocated for T4b rectal cancer with anterior organ invasion without convincing evidence. This study aimed to explore the patterns of treatment failure for locally advanced T4b rectal cancer treated using neoadjuvant chemoradiotherapy (NCRT) and surgery. This information may help to clarify whether the current definition of the clinical target volume (CTV) is still appropriate. MATERIALS AND METHODS: We retrospectively analyzed data from 126 patients with locally advanced T4b rectal cancer who received NCRT, without elective EIN irradiation, followed by surgery between January 2010 and October 2018. Pretreatment magnetic resonance imaging was used to identify the T4b disease in all cases. The locoregional recurrence (LRR) rate and EIN failure rate were evaluated, and the LRR locations were identified using a three-dimensional model. RESULTS: After a median follow-up of 53.9 months, LRR occurred in 11.1% of patients (14/126). All LRRs were located in the previously irradiated fields and below the S2-S3 junction. The EIN failure rate was 0.8% (1/126) among all patients and 1.8% (1/56) in the group with anterior genitourinary organ invasion. The estimated 4-year distant relapse-free survival, disease-free survival and overall survival were 79.3%, 73.2% and 86.9%, respectively. CONCLUSIONS: It may be feasible to exclude the external iliac region from the CTV during NCRT for locally advanced T4b rectal cancer. However, further studies are needed to clarify whether the cranial border of the CTV can be lowered.

National postoperative and oncologic outcomes after pelvic exenteration for T4b rectal cancer.

BACKGROUND AND OBJECTIVES: Studies reporting outcomes after pelvic exenteration for rectal cancer are limited. The objective of this study was to evaluate early postoperative and oncologic outcomes in a national multi-institutional cohort. METHODS: Using the National Cancer Database (NCDB), which collects data from over 1500 commission on cancer (CoC)-accredited hospitals, we analyzed patients undergoing pelvic exenteration for T4b rectal adenocarcinoma. RESULTS: There were 1367 pelvic exenterations performed in 552 hospitals. Median age was 60 years, the majority of patients (n = 831; 60.8%) were female. Neoadjuvant radiation was used only in 57%; 24.3% of resections had positive margins. Following exenteration, 30-day mortality rate, 90-day mortality rate, and readmission rates were: 1.8%, 4.4%, and 7.4%. Age ≥ 60 years and higher Charlson-Deyo comorbidity index were independently associated with increased 90-day mortality (P < .001). Overall survival (OS) was 50 months. After adjustment of significant covariates, negative margin status (adjusted HR, 0.6, 95% CI, 0.5-0.8; P < .001) and receipt of perioperative radiation or chemoradiation (adjusted HR, 0.5; 95% CI, 0.4-0.6; P < .001) were significantly associated with decreased risk of death. Only 71% of the patients received perioperative radiation. CONCLUSIONS: Pelvic exenterations are being performed safely in Coc-accredited hospitals. However, up to one fourth of patients undergo resections with positive margins or are subject to underutilization of perioperative radiation therapy. Increased use of radiation may increase negative margin resections and improve patient outcomes.