Can a novel MRI staging system for low rectal cancer aid surgical planning?

BACKGROUND: Low rectal cancers are associated with worse outcomes in comparison with mid and upper rectal tumors. OBJECTIVE: This study aimed to assess the predictive accuracy of MRI in identifying the correct surgical approach based on the mesorectal and extralevator planes. DESIGN: This study involved the retrospective analysis of MRI and histopathology data of 33 patients with low rectal cancer, with the use of an anatomically based staging system. Three radiologists reported on the available surgical planes of excision based on the predicted relationship of tumor to key anatomical features. MRI-predicted planes of excision were then compared with the histopathological planes actually required, with the use of the same staging criteria. SETTINGS: The study was conducted at 4 English district general hospitals. PATIENTS: Unselected patients with low rectal cancer, all of whom were participants in a multicenter study, were eligible for this study. MAIN OUTCOME MEASURES: : The main outcome measured was the accuracy of operative plane prediction on MRI. RESULTS: : On pathological analysis, the mesorectal plane would have been sufficient to achieve a clear margin in 28 of 33 (84.9%) of cases. The extralevator plane was required in 5 of 33 (15.1%). Planes were correctly predicted by MRI in 29 of 33 cases by radiologist 1 and 24 of 33 cases by radiologists 2 and 3 with an accuracy of 87.9% and 72.7%. Overstaging (extralevator plane predicted when a mesorectal plane would have sufficed) occurred in 3 of 33 and 7 of 33 cases. Understaging (mesorectal plane predicted when an extralevator plane was required) occurred in 1 of 33 and 2 of 33 cases. The positive and negative predictive values of MRI in determining the histopathological plane of excision required were 57% and 96% for radiologist 1 and 30% and 91% for radiologists 2 and 3. LIMITATIONS: This study was limited by its retrospective nature and its relatively small patient numbers. No account was taken of postoperative function when recommending the surgical plane. CONCLUSIONS: This supports an anatomically based MRI staging system for low rectal cancer to predict the planes of surgical excision. This may help to reduce margin positivity and to improve outcome in patients with low rectal cancer.

Reduced genomic tumor heterogeneity after neoadjuvant chemotherapy is related to favorable outcome in patients with esophageal adenocarcinoma.

Neoadjuvant chemo(radio)therapy followed by surgery is the standard of care for patients with locally advanced resectable esophageal adenocarcinoma (EAC). There is increasing evidence that drug resistance might be related to genomic heterogeneity. We investigated whether genomic tumor heterogeneity is different after cytotoxic chemotherapy and is associated with EAC patient survival. We used arrayCGH and a quantitative assessment of the whole genome DNA copy number aberration patterns ('DNA copy number entropy') to establish the level of genomic tumor heterogeneity in 80 EAC treated with neoadjuvant chemotherapy followed by surgery (CS group) or surgery alone (S group). The association between DNA copy number entropy, clinicopathological variables and survival was investigated.DNA copy number entropy was reduced after chemotherapy, even if there was no morphological evidence of response to therapy (p<0.001). Low DNA copy number entropy was associated with improved survival in the CS group (p=0.011) but not in the S group (p=0.396).Our results suggest that cytotoxic chemotherapy reduces DNA copy number entropy, which might be a more sensitive tumor response marker than changes in the morphological tumor phenotype. The use of DNA copy number entropy in clinical practice will require validation of our results in a prospective study.