PV QA 1 - Poster Viewing Q&A 1
Purpose/Objective(s):A three-grade system is standardly used to describe the total mesorectal excision quality (TMEq). TMEq is well known independent prognostic factor associated with local tumor recurrence and disease progression. On the contrary, neoadjuvant chemoradiotherapy (NCRT) reduces the risk of tumor recurrence in rectal adenocarcinoma, but may influence TMEq. A time to surgery (TTS) after finishing NCRT and its influence on TMEq and tumor control was subject of our evaluation.
Materials/Methods:In prospective registry, 236 patients with complete records after NCRT and TME were analyzed. NCRT involved radiotherapy with 45 Gy in 25 fractions to the pelvic area (rectum, pararectal, presacral, and internal iliac lymph nodes); a supplementary boost dose was applied to the tumor itself (5.4 Gy in 3 fractions). Continuous 5-FU infusion at a dose of 200 mg/m2/24 hours was applied concurrently for the entire duration of radiotherapy. NCRT was followed by TME after 9 weeks in average (median 9.4 +/- SD 2.5, range 3.6 – 19). TMEq was parametrically analyzed as following: I – complete TME with intact mesorectal plane; II – incomplete TME with intramesorectal plane defects > 5 mm deep; III – poor TME with defects to muscularis plane. Logrank tests, Chí-square tests, and Cox/Logistic/Linear univariate and multivariate regression analyses were used to study the purpose.
Results:With median follow-up of 47.5 months (6-97): 58 patients (24.6%) have died or were lost to follow-up; 64 patients (17.1%) had tumor recurrence, 15 of them (6.4%) with isolated local recurrence (LR). Three year overall survival (OS) was 83.8% (95%CI 78.9%-88.7%), with disease-free survival (DFS) of 77.7% (95%CI 72.1%-83.3%). Several characteristics had statistically significant impact on survival and local recurrence, however TTS was not associated with OS, DFS, nor LR. TMEq was found to be associated with LR in univariate analysis, but not in multivariate, where pathological tumor stage and resection margin status remained dominant predictors. TMEq was negatively influenced mainly by lower tumor location, longer TTS, higher tumor and nodal stage, presence of tumor perforation and perineural invasion. TMEq was also associated with close/positive resection margins. Nonetheless, TTS remained a strong predictor of TMEq after multivariate analyses.
Conclusion:Time to surgery was proved to be a strong and independent predictor of TMEq in our prospective study, taking into account all eventual confounding factors. With longer time between NCRT and surgery, less complete TME with intact mesorectal plane were observed. However, TTS was not associated with survival deterioration, or increased tumor recurrence at 3 years. These were negatively influenced by other factors interfering with TMEq, especially by pathological tumor stage and resection margin status.
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