Prognostic analysis and beneficiary identification of adjuvant external beam radiotherapy for stage pT4b sigmoid colon cancer

Abstract

The clinical efficacy of adjuvant radiotherapy in sigmoid colon cancer remains questioned. To evaluate the clinical efficacy of adjuvant external beam radiotherapy (EBRT) for patients with pathologic stage T4b sigmoid colon cancer. Patients with stage pT4b sigmoid colon cancer receiving adjuvant EBRT or not followed by surgery between 2004 and 2016 were extracted from the Surveillance, Epidemiology, and End Results database. Analysis of overall survival (OS) was performed using Kaplan–Meier curves and prognostic factors were identified using Cox proportional hazards regression models with 95% confidence intervals within the entire cohort. A risk-stratification system was then developed based on the β regression coefficient. Among 2073 patients, 284 (13.7%) underwent adjuvant EBRT. The median OS in the group receiving adjuvant EBRT was significantly longer than that in the non-radiotherapy group (p < 0.001). Age, serum carcinoembryonic antigen (CEA) level, perineural invasion, lymph node dissection (LND) number, and adjuvant EBRT were independent factors associated with OS. A risk‐stratification system was generated, which showed that low‐risk patients had a higher 5-year survival rate than high-risk patients (75.6% vs. 42.3%, p < 0.001). Adjuvant EBRT significantly prolonged the 5-year survival rate of high-risk patients (62.6% vs. 38.3%, p = 0.009) but showed no survival benefit among low‐risk patients (87.7% vs. 73.2%, p = 0.100). Our risk‐stratification model comprising age, serum CEA, perineural invasion, and LND number predicted the outcomes of patients with stage pT4b sigmoid colon cancer based on which subgroup of high-risk patients should receive adjuvant EBRT.

Postoperative locoregional recurrence pattern and treatment management of stage pT4 sigmoid colon cancer: a retrospective cohort study

“…These findings have also been confirmed by other studies [ 12 , 44 ]. Previously, we also found that some sigmoid colon cancer patients may benefit from postoperative RT [ 17 ], and this study once again demonstrated the positive effect of adjuvant RT on survival from the perspective of locoregional recurrence.…”

“…Using SEER*Stat 8.3.8 (IMS, Inc. USA. https://seer.cancer.gov/seerstat/ ), cases were identified based on the third edition of the International Classification of Diseases for Oncology code, as described in a previous article [ 17 ]. The screening process is illustrated in Additional file 1 .…”

“…The sigmoid colon is much lower and easier to position on the RT target area delineation system than other parts of the colon, making adjuvant RT plausible for sigmoid colon cancer [ 15 , 16 ]. Our previous study also found that adjuvant RT could prolong survival for stage pT4bN0-2M0 sigmoid colon cancer patients [ 17 ]. The National Comprehensive Cancer Network guideline of colon cancer indicates that postoperative RT can be considered for stage T4 with penetration into a fixed structure.…”

Identifying the long-term survival beneficiary of chemotherapy for stage N1c sigmoid colon cancer

“…Tumor differentiation was divided into three groups: well/moderately differentiated, poorly differentiated/undifferentiated, and unknown. Tumor size was classified into three categories: < 5 cm, ≥ 5 cm, and unknown 11 , 12 . Serum carcinoembryonic antigen (CEA) status was classified into three categories: elevated, normal, and unknown.…”