The 2002 Willmar Cancer Center report is focused on colorectal cancer (CRC). Adenocarcinoma of the colon and rectum combined is the most common cancer of the gastrointestinal tract and third most frequent site of cancer and cause of death in the United States. With more than 570,000 new cases each year, it is also a worldwide health problem of great importance, particularly in Western countries. Approximately 148,300 new cases of cancer and 56,600 deaths from cancer of the colon and rectum are estimated in 2002. Five-year survival is about 60 percent overall.

In an individual lifetime, the risk of colorectal cancer is about 6 percent in the US (Table 1). More than 90 percent of the cases develop after the age of 50 (Figure 1). Comparing the incidence by gender in the United States to those at Rice Memorial Hospital (RMH) between 1992-1999, 64.6 percent were male versus 49 percent at RMH. The incidence rate for women nationwide was 46.7 percent versus 51 percent at RMH (Figure 2). The mortality rate for men in the United States between 1992-1999 was 27.1 versus 26 percent at RMH and the mortality rate for women in the United States was 18.9 percent compared to 26 percent at RMH (Figure 3). Because women live longer than men, the total number of cases and deaths may be higher in women than men.

Incidence and mortality from colorectal cancer vary by ethnicity and race: African Americans, 50.1 and 22.8 percent; Caucasians, 42.9 and 16.8 percent; Asian/Pacific Islander, 38.2 and 10.7 percent; American Indian/Alaska Native, 28.6 and 10.3 percent; Hispanics 28.4 and 10.2 percent, respectively (Table 2). Adenocarcinoma of the colon and rectum varies widely in frequency in different parts of the world. The incidence varies from 3.5 per 100,000 in India to 32.3 per 100,000 in Connecticut. In the United States, rectal cancer incidence has declined during the past 50 years.

The most frequent tumors that occur in the large intestine are benign polyps. Population studies have demonstrated a twofold or threefold increased risk of colon cancer in first-degree relatives of individuals with colon cancer (Table 1). Approximately 75 percent of new cases occur in individuals at average risk. About 20 percent of CRC cases develop in patients with family history. The Familial Adenomatous Polyposis syndromes (FAP) account for approximately 1 percent of colorectal cancer, whereas the Hereditary Non-Polyposis Colorectal Cancer (HNPCC) inherited conditions may be responsible for up to 5 percent (Figure 4). Fewer than 5 percent of adenomas develop into carcinomas. Several important factors in this transformation can be identified, especially size, histology type, and epithelial dysplasia. The frequency of cancer in adenomas less than 1 cm is one to 3%; in those between 1-2 cm, 10%; and in those more than 2 cm, more than 40%. The highest malignancy rate is associated with a villous growth pattern. Invasive neoplasm has been found in 40 percent of the villous tumors, in fewer than 5 percent of the tubular adenomas, and in 23 percent of the tubulovillous variety. With severe dysplasia, the rate of malignant transformation rises to 27 percent.

Colorectal cancer is a preventable disease. Current CRC screening guidelines for average risk patients by American College of Gastroenterology, American Cancer Society and Agency for Health Care Policy and Research include preferably colonoscopy once every 10 years. Alternative strategies include testing for fecal occult blood annually combined with flexible sigmoidoscopy every five years, both beginning at age 50 years. Patients with abnormal findings, e.g., a positive fecal occult blood test or distal adenomas, should be referred for colonoscopic evaluation or another option, a double contrast barium enema every 5-10 years.

Adenocarcinoma of the colon and rectum (colorectal carcinoma) is the most common malignancy of colon and rectum. The other malignant tumors of the colon include anal carcinoma (squamous or transitional cell types), lymphoma, leiomyosarcoma, malignant carcinoid tumor, and Kaposi's sarcoma.

Despite continuing advances in diagnosis and therapy, long-term survival has not improved significantly over the last four decades, and almost 50 percent of CRC patients will eventually die of their disease. Survival is related to stage at diagnosis. The most recent five-year survival rates for SEER and RMH are presented in Table 3. An overall survival rate for all stages is 61.1 percent for SEER and slightly higher, 63.4 percent, at RMH. Between 1996-2001, 266 colon cancers were diagnosed. Of those 266 cases, 22.9 percent of the cases were diagnosed at Stage I, 32 percent at Stage II, 24.1 percent at Stage III, followed by 12.8 percent at Stage IV (Figure 5).
The modern approach to management is multidisciplinary. The most important goal of treatment for primary malignancies of the colon and rectum is complete removal of the tumor mass including lymph nodes and omentum. Cancer of the right and left colon are treated by hemicolectomy. Distal rectal cancers are resected by abdominoperineal approach. Radiation therapy plays an important role in the management of rectal cancer. Preoperative radiation therapy is often combined with fluorouracil and leucovorin in an effort to decrease local recurrence and distant spread. Patients with resected colonic cancer with lymph node spread have improved survival if treated with adjuvant therapy, combination of fluorouracil and leucovorin for six months. New drugs, such as topoisomerase I inhibitors (camptothecins) and oxaliplatin, have therapeutic activity for palliation in patients with metastatic spread.

The role new diagnostic preventive therapies are being actively evaluated including Virtual CT and MRI scans, EUS for staging of rectal cancer, and stool studies for DNA markers. The role of high fiber diet, folic acid, calcium, Ursodiol and COX-2 inhibitors are being actively investigated as chemoprevention of polyps and CRC.

(Table 1.)

(Figure 1.)

2001 COLON CANCER - AGE AT DIAGNOSIS

(Figure 2.)

1992 - 1999 COLON CANCER INCIDENCE

(Figure 3.)

1992 - 1999 COLON CANCER MORTALITY

(Table 2.)

*Source: American Cancer Society Cancer Facts & Figures 2002

(Figure 4.)

(Table 3.)

*SEER: The Surveillance, Epidemiology and End Results Program established by the National Cancer Institute. This program has selected certain geographic areas submitting data which represent the country as a whole.

(Figure 5.)

COLON CANCER - STAGE AT DIAGNOSIS, 1996 - 2001
Chart Represents 266 Cases

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