Factors Associated with Nodal Involvement of Rectal Adenocarcinomas

Sphincter-saving surgery with and without pre-operative radiation therapy as treatment for adenocarcinoma of the mid-rectum

AIMS

To determine if pre-operative radiation therapy induces a local response in patients with complete tumour penetration into the rectal wall and allows for anal sphincter preservation, we compared the results from pathological specimens and local recurrences as measurable end-points in patients treated with pre-operative radiation therapy plus low anterior resection vs. those only treated with low anterior resection.

METHODS

From January 1986 to December 1992, we treated 62 patients with mid-rectal adenocarcinoma (5-10 cm from the anal verge as determined by rigid proctosigmoidoscopy with the patient in the jackknife position). Pre-operative evaluation included: complete blood cell count, chemistry profile and the determination of carcinoembryonic antigen, chest X-ray, barium enema or colonoscopy and CT scan of the abdomen and pelvis. Only tumours potentially curative by resection in patients with performance status 0-2 (ECOG) were included. Twenty-one patients received pre-operative radiation therapy at a dose of 45 Gy delivered to the pelvis; 4-8 weeks later a low anterior resection was performed. Forty-one patients were treated with low anterior resection alone. Surgical specimens were classified according to the Astler-Coller modification of Dukes' classification.

RESULTS

There were 36 males and 26 females, with a mean age of 56 years. The surgical specimens of those treated only with surgery were classified as: A, 5; B1, 4; B2, 15; C1, 2; and C2, 15. Postirradiated specimens: no residual tumour, 3; A, 4; B1, 4; B2, 7; C2, 3. One surgical death occurred in the group who underwent surgery alone. The median follow-up was 50 months in patients treated with surgery alone vs. 62 months in the combined approach group. Local recurrences occurred in 15/40 patients treated with surgery alone and in 2/21 of those treated with the combined approach (P = 0.043). Anal sphincter continence was classified as excellent by 24/40 patients treated with surgery only and by 18/21 patients treated with the combined approach. The 5-year survival period was 58% in the surgery only group and 82% in the group with combined treatment (P = 0.08).

CONCLUSIONS

The use of pre-operative radiation therapy plus low anterior resection was associated with a lower rate of local recurrence and with a higher number of surgical specimens with no lymph node metastases. Thus, this combined treatment modality should be further evaluated as a possible treatment of mid-rectal cancers in good surgical candidates selected for sphincter-saving procedures.

Local surgical treatment of rectal cancer

Patients with cancer of the lower third of the rectum can avoid both the morbidity of an APR and the need for a permanent colostomy by having the cancer removed by local excision. If the surgeon clinically suspects that a patient has an early cancer, the first step should be local excision of the tumor. The pathological features of the cancer specimen will then indicate the next step in treatment. This can range from no further therapy to proctectomy with or without an anastomosis (Table 2). Patients with a low risk of local failure can be treated by excision alone. Those with a higher risk of local failure should undergo APR or LAR or enter a protocol to determine the role of local excision and adjuvant chemoradiation.

Prognostic profile in rectal cancer

PURPOSE

The purpose of this article was to review the prognostic factors of significance in rectal cancer.

METHODS

This is a retrospective review of various reports and an examination of our data.

RESULTS

Current imaging techniques with endorectal ultrasound, magnetic resonance imaging with a rectal probe, and possibly tagged monoclonal antibodies allow for presurgical assessment of the invasion of the rectal wall and detection of lymph node involvement.

CONCLUSIONS

Tumor penetration of the rectal wall and lymph node metastases are the most important prognostic indicators in rectal cancer and predict local and distant recurrences. When lymph node metastases occur, they are more common in small lymph nodes (< 5 mm). Patients with lymph node metastases always need to be considered for multimodality therapy. Tumors larger than or equal to T3 or with associated lymph node metastases should not be treated with sphincter-saving surgical procedures alone.

Incidence of metastases from rectal adenocarcinoma in small lymph nodes detected by a clearing technique

The incidence of metastases from primary adenocarcinoma of the rectum in lymph nodes smaller than 5 mm is not known. Lymph nodes measuring less than or equal to 5 mm usually are not detected by manual techniques of examination of the surgical specimen. This retrospective analysis describes the results when a lymph node clearing technique that identifies lymph nodes as small as 1 mm was used to treat surgical specimens from 27 consecutive patients with rectal adenocarcinoma who underwent abdominoperineal resection with a curative intent and for whom all pathologic data were retrievable. Nine hundred thirty lymph nodes were found, with an average of 34 lymph nodes per specimen (range 0-88). Seventy-two of the 345 lymph nodes found in patients with Dukes C tumors were found to have metastases. Fifty-six (78 percent) of these 72 lymph node metastases occurred in lymph nodes measuring less than or equal to 5 mm. Three lymph node metastases were found in the perianal zone, 53 in the perirectal zone, and 16 in the pericolonic zone. Lymph node metastases from rectal adenocarcinomas often will occur in lymph nodes smaller than 5 mm. We concluded that the use of lymph node clearing techniques discovers these metastases, thereby offering the potential for enhanced staging of primary rectal adenocarcinomas.