Prognostic Significance of Mucinous Histologic Subtype on Oncologic Outcomes in Patients With Colorectal Cancer

PURPOSE: Mucinous adenocarcinomas account for about 10% of all colorectal cancers. This study aimed to investigate the prognostic impact of mucinous histologic subtype on oncologic outcomes in patients with colorectal cancer. METHODS: This retrospective study was performed at two large tertiary university hospitals. We analyzed the characteristics, prognostic factors, and survival of patients with colorectal cancer who were treated and followed up between 2000 and 2013. RESULTS: Totally, 144 of 1,268 patients with a colorectal adenocarcinoma (11.4%) had mucinous histologic subtype. Statistically significant results found in this research are as follows: Mucinous histologic subtype tended to present in younger patients and to have larger tumor size, higher histologic grade, higher node stage, larger number of positive nodes, and higher rate of perineural invasion compared to nonmucinous histologic subtype. On the univariate analysis, mucinous subtype was a prognostic factor for disease-free and overall survival. On the multivariate analysis, primary tumor location, node stage and lymphatic-vascular invasion were independent prognostic factors for the local control rate. Rectal tumor location, higher disease stage, tumor grade II, and presence of lymphatic-vascular invasion had negative influences on disease-free survival, as did rectal tumor location, higher disease stage and presence of lymphatic-vascular invasion on overall survival. CONCLUSION: Mucinous histologic subtype was associated with some adverse pathologic features in patients with colorectal cancer; however, it was not an independent prognostic factor for oncologic outcome.

Efficacy and Safety of Low-Dose-Rate Endorectal Brachytherapy as a Boost to Neoadjuvant Chemoradiation in the Treatment of Locally Advanced Distal Rectal Cancer: A Phase-II Clinical Trial

PURPOSE: Despite advances in rectal cancer treatment over the last decade, local control and risk of late side effects due to external beam radiation therapy (EBRT) remain as concerns. The present study aimed to investigate the efficacy and the safety of low-dose-rate endorectal brachytherapy (LDRBT) as a boost to neoadjuvant chemoradiation for use in treating locally advanced distal rectal adenocarcinomas. METHODS: This phase-II clinical trial included 34 patients (as the study arm) with newly diagnosed, locally advanced (clinical T3-T4 and/or N1/N2, M0) lower rectal cancer. For comparative analysis, 102 matched patients (as the historical control arm) with rectal cancer were also selected. All the patients were treated with LDRBT (15 Gy in 3 fractions) and concurrent chemoradiation (45-50.4 Gy). Concurrent chemotherapy consisted of oxaliplatin 130 mg/m2 intravenously on day 1 plus oral capecitabine 825 mg/m2 twice daily during LDRBT and EBRT. RESULTS: The study results revealed a significant differences between the study arm and the control arm in terms in the pathologic tumor size (2.1 cm vs. 3.6 cm, P = 0.001), the pathologic tumor stage (35% T3-4 vs. 65% T3-4, P = 0.003), and the pathologic complete response (29.4% vs. 11.7%, P < 0.028). Moreover, a significantly higher dose of EBRT (P = 0.041) was found in the control arm, and a longer time to surgery was observed in the study arm (P < 0.001). The higher rate of treatment-related toxicities, such as mild proctitis and anemia, in the study arm was tolerable and easily manageable. CONCLUSION: A boost of LDRBT can optimize the pathologic complete response, with acceptable toxicities, in patients with distal rectal cancer.