The Role of Colonoscopy and Flexible Sigmoidoscopy in Screening for Colorectal Carcinoma

MARY JANE WARDEN, M.D., NICHOLAS J. PETRELLI, M.D., LEMUEL HERRERA, M.D., ARNOLD MITTELMAN, M.D.

Warden M J, Petrelli N J, Herrera L, Mittelman A. The role of colonos- copy and flexible sigmoidoscopy in screening for colorectal carcinoma. Dis Colon Rectum 1986;30:52-54.

Six hundred thirty-two patients were referred to the Colorectal Clinic from February 1983 to February 1986 for screening with the Pentax 65 cm flexible sigmoidoscope. Forty-nine of these patients (8 percent) had adenomatons polyps. There were 27 males and 22 females. The mean distance examined by the 65 cm flexible sigmoidoscope was 55 can. Five patients were excluded from analysis, leaving 44 patients who under- went colonoscopy to the cecum. At the time of colonoscopy, 15 of the 44 patients (34 percent) had one or more adenomatous polyps beyond reach of the 65 cm flexible sigmoidoscope. The remaining 29 patients who underwent colonoscopy had no polyps beyond reach of the 65 cm flexible sigmoidoscope. Thirty adenomatous polyps, one invasive car- cinoma of the ascending colon, and one hyperplastic polyp were found in these 15 patients. In summary, 34 percent of patients found to have adenomatons polyps within reach of the 65 cm flexible sigmoidoscope harbored one or more adenomatous polyps in the proximal colon at the time of colonoscopy. A positive 65 cm flexible sigmoidoscope examination requires colonoscopy to identify and remove proximal premalignant lesions, thereby aborting the polyp-cancer sequence. [Key words: Colonoscopy; Sigmoidoscopy; Screening; Colorectal; Car- cinoma]

COLORECTAL CANCER IS THE second leading cause of carcinoma-related deaths in the United States, with 140,000 new cases estimated to occur in 1986.a Survival is correlated closely with the stage of disease at diagnosis. While the overall five-year survival rate of all patients with colorectal malignancy is 40 percent, in patients with early lesions the survival rate is greater than 90 percent, z, 3 Screening programs have been developed to detect colt- rectal lesions early in their natural history when the pos- sibility of cure is greatest. 4 The optimum screening

Received for publication July 28, 1986. Address reprint requests to Dr. Petrelli: Department of Surgical

Oncology, Roswell Park Memorial Institute, 666 Elm Street, Buffalo, New York 14263.

From the Department o] Surgical Oncology, Roswell Park Memorial Institute,

Bu]falo, New York

program would not only detect early carcinomas, but also those patients harboring premalignant polyps. This report examines the colonoscopic findings following the discovery of polyps by the Pentax 65 cm flexible sigmoido- scope in a screening program for colorectal neoplasms at Roswell Park Memorial Institute.

M a t e r i a l s a n d M e t h o d s

Patients with a positive stool guaiac test, history of hematochezia, change in bowel habits, or a family history of colorectal carcinoma were referred from the Screening Clinic to the Colorectal Clinic for further investigation. All patients underwent a history and physical examina- tion followed by sigmoidoscopy with the 65 cm Pentax flexible sigmoidoscope. Patients with a normal flexible sigmoidoscopy underwent a double contrast barium enema. These results have been reported previously. 5 Patients who had polyps (adenomatous or hyperplastic) within reach of the 65 cm flexible sigrnoidoscope were referred for colonoscopy three to six weeks later. During flexible sigmoidoscopy, biopsy of the polyp was per- formed; however, no attempt was made to totally excise the polyp until colonoscopy. Following a two-day bowel preparation consisting of a liquid diet, cathartics, and enemas, colonoscopy and polypectomies with a 160 cm Olympus colonoscope were performed under intrave- nous sedation consisting of Demerol| and Valium|

R e s u l t s

There were 632 patients referred to the Colorectal Clinic from February 1983 to February 1986 who under-

52

Volume 30 Number 1 C O L O R E C T A L CARCINOMA SCREENING 5 3

TABLE 1. Colonoscopy Following ,4 Positive 65 cm Flexible Sigmoidoscopy

632 Screening Patients

49 patients--adenomatous polyps found on

flexible sigmoidoscopy

5 patients 15 patients 29 patients excluded polyps beyond flexible negative colonoscopy

scope at colonoscopy beyond 65 cm

1 patient 30 No villous invasive cancer adenomatous polyps adenomas

11 patients--hyperplastic polyps found on flexible sigmoidoscopy ~ negative colonoscopy

went endoscopy with the 65 cm flexible sigrnoidoscope. Of these, 49 patients (8 percent) who had adenomatous polyps form the basis of this study. There were 27 males and 22 females. The mean age was 60 years. The mean distance examined by the 65 cm flexible sigmoidoscope was 55 cm. Four patients refused colonoscopy and in a fifth patient colonoscopy was unsuccessful in negotiating a redundant sigmoid colon. These five patients were excluded from analysis. The remaining 44 patients underwent colonoscopy to the cecum. Of 11 additional patients found to have hyperplastic polyps in the recto- sigmoid during flexible sigmoidoscopy, none had addi- tional polyps in the remainder of the colon via co- lonoscopy.

In these 44 patients, colonoscopy revealed one or more adenomatous polyps beyond reach of the 65 cm flexible sigmoidoscope in 15 patients (34 percent) and no polyps in the remaining 29 patients (Table 1). A total of 30 adenomatous polyps, one invasive carcinoma of the ascending colon, and one hyperplastic polyp were found in these 15 patients. These lesions ranged from 3 mm to 4 cm (mean, 6 to 7 mm).

Three or more adenomatous polyps were found in five of the 15 patients with one patient having five polyps and another eight adenomatous polyps beyond 60 cm from the anal verge (Table 2). No villous adenomas were encountered. Five patients had atypia within the ade- nomatous polyp and these atypical changes were present in both small polyps and those greater than 2 cm in diameter. The invasive carcinoma of the ascending colon

was discovered in a patient who was asymptomatic and had been referred because of a family history of colorectal carcinoma. Family history was the reason for screening in eight of the 15 patients with polyps beyond reach of the 65 cm flexible sigmoidoscope.

D i s c u s s i o n

The present study investigates the chances of a patient having polyps in the proximal colon when adenomatous polyps are present in the distal 65 cm of the colorectum. Adenomatous polyps are known to be precursors to the development of adenocarcinoma. 6 Adenomas can ante- date, coexist with, or develop into carcinomas. The pres- ence of varying grades of atypia in adenomatous polyps lends credence to the polyp-cancer sequence theory, The progression of an adenomatous polyp to cancer is not

TABLE 2. Number o /Polyps per Patient

e~

e'~

z

-7

I

1 2 3 4 5

Number of Polyps 7 8

~ , , , Dis. Col. & Rect. WARDEN, ET AL. January 1987

immutable, however, since it may take five to ten years, or more, [or the malignant transformation to occur. Re- moval of these premalignant polyps should decrease the anticipated incidence of cancer. In a 25-year study of periodic proctosigmoidoscopy and polypectomy, Gil- bertsen 7 demonstrated an 85 percent reduction in the anticipated incidence of rectosigmoid cancer, while the anticipated number of malignancies did develop in the remainder of the colon not subjected to examination.

Although the evidence supports the fact that if ade- nomatous polyps are eliminated, the risk of cancer may be diminished, the problem of determining who harbors these premalignant lesions in their colon remains. To perform colonoscopy in al! patients seen in the screening environment, however, would be a formidable task in both time and expense, beyond the monetary resources available in this budget-conscious era. A way must be found to "screen the screenees." In a previous study the authors demonstrated that in a screening population, if a patient had a negative 65 cm flexible sigmoidoscopy, there was a 1.8 percent chance of encountering an ade- nomatous polyp in the remainder of the colon. 5 In the present study it was found that 34 percent of the patients harbored one or more adenomatous polyps in the prox- imal colon if one were to be found in the distal 65 cm, an 18-fold increase in probability as compared with a nega- tive sigmoidoscopic examination. In a review of 3,000 patients with polyps, Muto et al. 8 found that 20 percent of patients had multiple neoplasms, a figure which proba-

bly underestimates the prevalence since diagnosis was established by barium enema, not colonoscopy.

Since the risk of cancer rises with the number as well as the size of the adenomas, a positive flexible sigmoidos- copic examination identifies a subset of patients at increased risk for the development of colorectal carcino- ma when positive for adenomatous polyps. Colonoscopy is indicated in these patients, land ideally will identify and extirpate the premalignant lesions, aborting the polyp- cancer progression.

References

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Management and survival of adenocarcinoma of the rectum in the United States: results of a national survey by the American Col- lege of Surgeons. Oncology 1982;39:265-73.

3. Evans JT, Vana J, Aronoff BL, Baker HW, Murphy GP. Manage- ment and survival of carcinoma of the colon: results of a national survey by the American College of Surgeons. Ann Surg 1978;188: 716-20.

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5. Warden MJ, Petrelli NJ, Herrem L, Mittelman A. Endoscopy versus double contrast barium enema in a screening program for col- orectai carcinoma Am J Surg (in press).

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8. Muto T, Bussey H J, Morson BC. The evolution of cancer of the colon and rectum. Cancer 1975;36:2251-70.