Abstract
BackgroundIn most guidelines, upper rectal cancers (URC) are not recommended to take neoadjuvant or adjuvant radiation. However, the definitions of URC vary greatly. Five definitions had been commonly used to define URC: 1) >10 cm from the anal verge by MRI; 2) >12 cm from the anal verge by MRI; 3) >10 cm from the anal verge by colonoscopy; 4) >12 cm from the anal verge by colonoscopy; 5) above the anterior peritoneal reflection (APR). We hypothesized that the fifth definition is optimal to identify patients with rectal cancer to avoid adjuvant radiation.MethodsThe data of stage II/III rectal cancer patients who underwent radical surgery without preoperative chemoradiotherapy were retrospectively reviewed. The height of the APR was measured, and compared with the tumor height measured by digital rectal examination (DRE), MRI and colonoscopy. The five definitions were compared in terms of prediction of local recurrence, survival, and percentages of patients requiring radiation.ResultsA total of 576 patients were included, with the intraoperative location of 222 and 354 tumors being above and straddle/below the APR, respectively. The median distance of the APR from anal verge (height of APR) as measured by MRI was 8.7 (range: 4.5–14.3) cm. The height of APR positively correlated with body height (r=0.862, P<0.001). The accuracy of the MRI in determining the tumor location with respect to the APR was 92.1%. Rectal cancer above the APR had a significantly lower incidence of local recurrence than those straddle/below the APR (P=0.042). For those above the APR, there was no significant difference in local recurrence between the radiation and no-radiation group. Multivariate analyses showed that tumor location regarding APR was an independent risk factor for LRFS. Tumor height as measured by DRE, MRI and colonoscopy were not related with survival outcomes. Fewer rectal cancer patients required adjuvant radiation using the definition by the APR, compared with other four definitions based on a numerical tumor height measured by MRI and colonoscopy.ConclusionsThe definition of URC as rectal tumor above the APR, might be the optimal definition to select patients with stage II/III rectal cancer to avoid postoperative adjuvant radiation.
Highlights
Preoperative chemoradiotherapy (CRT) has become an integral part of the multimodal treatment for stage II and III rectal cancer
The results demonstrated that fewer patients required radiation using the definition based on the anterior peritoneal reflection (APR) (61.5%) compared with the other four definitions using a numerical tumor height measured by MRI and colonoscopy (64.2%– 100.0%, Table 4)
Univariate and multivariate COX analyses demonstrated that tumor location relative to the APR was an independent risk factor of LRFS, while other tumor height related parameters measured by DRE, colonoscopy and MRI were not related to overall survival (OS), disease-free survival (DFS), or LRFS
Summary
Preoperative chemoradiotherapy (CRT) has become an integral part of the multimodal treatment for stage II and III rectal cancer. The benefit of radiation for upper rectal cancer (URC) is not clear. In the 2020 NCCN guidelines, URC was defined as a rectal tumor with inferior margin located between the anterior peritoneal reflection (APR) and the sacral promontory, as determined by MRI [1]. According to the 2017 ESMO guidelines, URC was defined as a tumor with inferior margin located at 10–15 cm from the anal margin, as measured by rigid sigmoidoscopy [2]. In the Chinese Society of Clinical Oncology (CSCO) 2018 guidelines, URC was defined as a tumor located 10 cm above the anal verge, as observed on the MRI [10]. Upper rectal cancers (URC) are not recommended to take neoadjuvant or adjuvant radiation. We hypothesized that the fifth definition is optimal to identify patients with rectal cancer to avoid adjuvant radiation
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