Deck 1 Flashcards
What are Prevalence estimates in unscreened individuals aged 50 years or older for invasive CRC, in situ carcinoma, adenoma of any size ?
Prevalence estimates reveal that in unscreened individuals aged 50 years or older, there is:
a 0.5% to 2.0% chance of harboring an invasive CRC.
a 1.0% to 1.6% chance of an in situ carcinoma,
a 25% to 40% chance of an adenoma of any size.
what is the most influential demographic factor on incidence?
Age impacts CRC incidence greater than any other demographic factor.
In what population the incidence incease dramatically? What showed a Surveillance, Epidemiology, and End Results (SEER) program based study?
There has been a dramatic increase in younger patients.
A study using data from the Surveillance, Epidemiology, and End Results (SEER) program found a rising incidence of CRC over the last 20 years in patients aged 20 to 49 years. The most pronounced growth was in the age group 40 to 44 years, where colon and rectal cancer increased 56% and 94%, respectively.
What studies reveal the importance of environmental exposure in CRC incidence?
Seminal studies have revealed that migrants from low-incident areas to high-incident areas assume the incidence of the host country within one generation.
What changed in the anatomic position for CRC?
Classically, colon cancer was believed to be a disease of the left or distal colon. However, the incidence of right-sided or proximal colon cancer has been increasing in North America and Europe.
Give 3 possible explanation to the anotomical shift in CRC?
This anatomic shift is likely multifactorial: (1) due to increased longevity; (2) as a response to luminal procarcinogens and carcinogens, which can vary between different sites of the colon and rectum; and (3) because of genetic factors, which can preferentially involve defects in mismatch repair genes with resulting microsatellite instability (MSI) in proximal colon cancers and chromosomal instability pathway predominant in left-sided colon and rectal cancers.
What is the relative risk (RR) for parents and siblings of patients with adenomas compared to spousal controls?
What increase this RR?
The relative risk (RR) for parents and siblings of patients with adenomas compared to spousal controls was 1.8, which increased to 2.6 if the proband was younger than age 60 years at adenoma detection.
Is there connection to BRCA1/2 mutations?
A new prospective study of 7,105 women followed for a mean of 5.5 years also found an association with the BRCA1 mutation, which conferred increased risk in women younger than 50 years (standardized incidence ratio 3.81). There was no discernible impact of BRCA2 or either mutation in older women.
Whatr is known about obesity and risk of CRC? Is there a gender difference?
Increased body mass may result in a twofold increase in CRC risk, with a strong association in men with colon but not rectal cancer. Weight gains during early to middle adulthood have also recently been linked with increased risk of colon but not rectal cancer. This relationship too seems more prominent in men than women in a large prospective study.
Is there a connection between ingestion of meat and risk of CRC? Give non supportive data?
Ingestion of red meat but not white meat is associated with an increased CRC risk.
Whether the total abstinence from red meat leads to a decreased CRC incidence has not been clarified, as there are studies with opposing results.Also unclear is whether the type of red meat or the degree of processing or cooking method make any difference.
Is there a connection between coffee consumption and CRC?
Caffeinated and decaffeinated coffee drinkers had a decreased risk of colon cancer, particularly of proximal tumors (hazard ratio [HR] for more than six cups a day = 0.62), and decaffeinated coffee drinkers also had a decreased risk of rectal cancer.
Coffee contains numerous bioactive compounds that may modulate cancer risk but previous epidemiologic studies investigating its role in CRC have yielded ambiguous results.
What mechanisms are belived to connect high fiber diet and low incidence of CRC?
A high-fiber diet was believed to dilute fecal carcinogens, decrease colon transit time, and generate a favorable luminal environment.
What is one of the most influential study that connect high fiber diet and low incidence of CRC? What this study shows?
The European Prospective Investigation into Cancer and Nutrition is an ongoing multicenter prospective cohort study, which was one of the largest and most influential studies to initially report an inverse association between dietary fiber and CRC. More long-term data, with a mean follow-up of 11 years and a near threefold increase in CRC cases, further supports this claim while providing a more precise estimation by fiber food source as well. After multivariable adjustments, total dietary fiber was found to be inversely associated with both colon and rectal cancers (HR per 10 g per day increased in fiber, 0.87), and this did not differ by age, sex, lifestyle, or other dietary factors.
What is non supportive data for the connection between high fiber diet and low incidence of CRC?
Other large, well-controlled studies show no inverse
In a study of nearly 90,000 women from ages 34 to 59 years who were followed for 16 years, no protective effect was noted between fiber and incidence of either adenomatous polyp or CRC. This was further corroborated by two large randomized controlled trials that evaluated high-fiber diets.
Is there a connection between Physical inactivity and CRC risk? What is the mechanism? Is there a procective recommendation for physical activity after diagnosis?
A sedentary lifestyle may account for an increased CRC risk more for colon then rectal cancer, although the mechanism is unclear.
Data suggest that physical activity after the diagnosis of stages I to III colon cancer may reduce the risk of cancer-related and overall mortality and that the amount of aerobic exercise correlates with a reduced risk of recurrence following resection of stage III colon cancer.
