Colorectal Cancer: A Review

Sarah Popek, MD, and Vassiliki Liana Tsikitis, MD
Published: Thursday, Nov 10, 2011

Abstract

Colorectal cancer is the third most common type of cancer diagnosed in the United States and is the third most common cause of cancer-related death. The majority of cases are sporadic, with hereditary colon cancer contributing up to 15% of all colon cancer diagnoses. Treatment consists of surgery for early-stage disease and the combination of surgery and adjuvant chemotherapy for advanced-stage disease. Management of metastatic disease has evolved from primary chemotherapeutic treatment to include resection of single liver and lung metastases in addition to resection of the primary disease and chemotherapy.

In the United States, colorectal cancer (CRC) is the third most common type of cancer diagnosed and the third most common cause of cancer-related death in men and women. In 2010, an estimated 102,900 new cases of colon cancer were diagnosed (49,470 male, 53,430 female) and 51,370 patients (26,580 male, 24,790 female) died from CRC.1 The death rate from colon cancer decreased over the preceding decade, from 30.77 per 100,000 people to 20.51 per 100,000 people.1 The lifetime risk of developing colon cancer in industrialized nations is 5% and is stable or decreasing.2 In contrast, the incidence in developing countries continues to rise, hypothesized to be due to increased exposure to risk factors.3 It has been estimated that 1.5 million people in the United States will be living with CRC by 2020.4 The financial burden of caring for this population is significant: $4.5 to $9.6 billion per year.5 Disparities among different racial and ethnic groups are well known and attributed to a variety of factors, including environmental exposures, tumor biology, lack of access to preventive health services, and inequities in treatment.6 Both incidence and mortality rates are higher in black patients than in white patients.7

Table 1. Risk Factors for Sporadic Colorectal Cancer34

Older age
Male sex
Cholecystectomy
Ureterocolic anastomosis
Hormonal factors: nulliparity, early menopause
Obesity
Diabetes mellitus
Environmental factors3
Diet (rich in meat, poor in fiber)
Sedentary lifestyle
Tobacco use
Prior irradiation
Occupational exposure (asbestos)
High alcohol intake
Personal history of sporadic tumors
History of colorectal polyps
History of colorectal cancer

Hereditary Colon Cancer

The majority of CRC cases are sporadic, with hereditary syndromes contributing approximately 5% to 15% of the incidence. There are many known risk factors for sporadic CRC, including nonmodifiable and modifiable variables (Table 1). Preventive measures should be targeted at tobacco use, dietary habits, and weight control.8 The inflammatory bowel disease (IBD) population is the second major category of patients at increased risk of CRC.9

The 2 main syndromes accounting for 5% of the inherited cases are hereditary nonpolyposis colon cancer (HNPCC) and familial adenomatous polyposis (FAP)10 The remaining 15% to 20% of inherited CRC cases do not have a clearly defined mechanism and likely result from a combination of gene polymorphisms, alterations in multiple susceptibility loci, and environmental influences.11 These cases are grouped into familial X CRC syndrome.


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