Though everyone is at risk of developing colon cancer, certain factors put some at a greater risk than others. The most important risk factor is increasing age. Individuals age 65 and older make up 73% of all newly diagnosed colorectal cancer cases. Other important risk factors include a family history of colorectal cancer, personal medical history of polyps or inflammatory bowel disease, and a diet high in animal fats. Men and African Americans have a higher incidence and mortality rate as compared with women and other ethnic groups. Factors that may decrease the risk of colorectal cancer include a diet high in fruits and vegetables, regular physical activity, hormone replacement therapy in postmenopausal women, and regular aspirin use.
Modern technology has increased the opportunity to prevent and control invasive disease. These modern techniques have reduced the incidence and mortality possibly due to increased screening and subsequent polyp removal. Screening is recommended beginning at age 50 for both men and women of average risk and before age 50 for individuals with a strong family or personal history of colorectal cancer. The American Cancer Society recommends three basic screening options. One option is the combination of Fecal Occult Blood Test (FOBT), Digital Rectal Exam (DRE), and sigmoidoscopy. Normal test results require an annual repeat FOBT and a sigmoidoscopy every 5 years. Another option is the colonoscopy and DRE. Normal results require a repeat test every 10 years. Finally, there is the doublecontrast barium enema and sigmoidoscopy combination. Normal results require a repeat exam every 5-10 years.
Of the 295 U.S. astronauts, 5 individuals (1.7%) were diagnosed with benign neoplasms at selection and 44 individuals (14.9%) were diagnosed after selection. The average time between selection and diagnosis was 18.4 years. Of the 899 comparisons in the database, 39 (4.3%) were diagnosed with benign neoplasms or a history of malignant neoplasms with an average time of 20.6 years between selection and diagnosis. The higher number of diagnoses for the astronaut group compared to the comparison participants corresponds to the higher intensity of medical care available to the astronauts. However, the average time between selection and diagnosis does not differ much between the two groups.
Technological advances have given us the tools necessary to detect and prevent this possibly fatal disease. Detection in its earliest stage has shown a 5 year survival rate of 91%; however, a regional cancer spread has a survival rate of 63%, and metastases to distant parts of the body has only a 7% survival rate. All LSAH participants are encouraged to comply with American Cancer Society screening recommendations to help reduce the incidence and mortality of colorectal cancer.
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