Faculty Bibliography

OBJECTIVE: The aims of this study were to use a comprehensive whole-mount pathologic analysis to characterize microscopic patterns of residual disease, as well as circumferential and distal resection margins, in rectal cancer treated with preoperative CMT; and to identify clinicopathologic factors associated with residual disease. SUMMARY BACKGROUND DATA: Recent studies have shown that preoperative combined modality therapy (CMT) for rectal cancer enhances rates of sphincter preservation. However, the efficacy of preoperative CMT in conjunction with a total mesorectal excision (TME)-based resection, in terms of resection margins using whole-mount sections, has not been reported. Furthermore, since patterns of residual disease and extent of distal spread following preoperative CMT are largely unknown, intraoperative determination of distal rectal transection remains a surgical challenge. METHODS: We prospectively accrued 109 patients with endorectal ultrasound (ERUS)-staged, locally advanced rectal cancer (T2-T4 and/or N1), located a median distance of 7 cm from the anal verge, requiring preoperative CMT, and undergoing a TME-based resection. Comprehensive whole-mount pathologic analysis was performed, with particular emphasis on extent of residual disease, margin status, and intramural tumor extension. Clinicopathologic factors associated with residual disease were identified. RESULTS: A sphincter-preserving resection was feasible in 87 patients (80%), and in all 109 patients, distal margins were negative (median, 2.1 cm; range, 0.4-10 cm). Intramural extension beyond the gross mucosal edge of residual tumor was observed in only 2 patients (1.8%), both < or =0.95 cm. There were no positive circumferential margins (median, 10 mm; range, 1-28 mm), although 6 were less than or equal to 1 mm. On multivariate analysis, residual disease was observed more frequently in distally located tumors (distance from anal verge <5 cm) (P = 0.03). CONCLUSION: Our comprehensive pathologic analysis suggests that, following preoperative CMT and a TME-based resection, distal margins of 1 cm may provide for complete removal of locally advanced rectal cancer. Although residual cancer following preoperative CMT was more likely in the setting of distally located tumors, occult tumor beneath the mucosal edge was rare and, when present, limited to less than 1 cm. Our results extend the indications for sphincter preservation, as distal resection margins of only 1 cm may be acceptable for rectal cancer treated with preoperative CMT

Familial adenomatous polyposis, caused by mutations in the adenomatous polyposis coli gene located at chromosome 5q21, is an autosomal dominant syndrome characterized by polyposis of the colon and rectum and nearly 100 percent progression to colorectal cancer. We report a case of familial adenomatous polyposis and mental retardation caused by a chromosomal deletion at 5q15-q22. Chromosomal analysis is considered part of the evaluation of children with mental retardation and developmental delay. The resulting karyotypes from high-resolution chromosomal analysis can help characterize large deletions, some of which involve known tumor suppressor genes. Because familial adenomatous polyposis may arise from de novo chromosomal deletions involving the adenomatous polyposis coli gene locus, individuals with chromosomal deletions involving 5q21 should be considered at-risk for familial adenomatous polyposis and offered standard screening with flexible sigmoidoscopy by 10 to 12 years of age

PURPOSE: Clinical assessment of rectal cancer response to preoperative combined-modality therapy (CMT) using digital rectal examination (DRE) has been proposed as a means of assessing efficacy of therapy. However, because the accuracy of this approach has not been established, we conducted a prospective analysis to determine the operating surgeon's ability to assess response using DRE. PATIENTS AND METHODS: Ninety-four prospectively accrued patients with locally advanced rectal cancer (T3/4 or N1) were evaluated with DRE and sigmoidoscopy in order to determine the following tumor characteristics: size, location, mobility, morphology, and circumference. Following preoperative CMT (50.40 Gy with fluorouracil-based chemotherapy) and under general anesthesia, the same surgeon estimated tumor response based on changes in these tumor characteristics, assessed via DRE. Percent pathologic tumor response was determined prospectively by a single pathologist using whole mount sections of the resected cancer. RESULTS: Clinical assessment using DRE underestimated pathologic response in 73 cases (78%). In addition, DRE was able to identify only 3 of 14 cases (21%) with a pathologic complete response. There were no clinical overestimates of response. None of the clinicopathologic tumor characteristics examined had a significant impact on DRE estimation of response. CONCLUSION: Clinical examination underestimates the extent of rectal cancer response to preoperative CMT. Given the inaccuracy of DRE following preoperative CMT, it should not be used as a sole means of assessing efficacy of therapy nor for selecting patients following CMT for local surgical therapies