The following factors increase the risk of bowel cancer

Modifiable Bowel Cancer Australia Risk Factors
Red and Processed Meat 
Eating too much red meat (e.g. beef, lamb, pork, goat) has been linked with an increased risk of bowel cancer.
Eating processed meats such as bacon, ham, salami and some sausages has been strongly linked with an increased risk of bowel cancer.
Starting step: If you choose to eat red meat, limit the amount to 500 grams cooked per week and avoid processed meatWhen barbecuing, partly cook meat in the oven first to reduce cooking times on open flames or grills.  Keep temperatures low and use marinades to protect meat from burning.
Modifiable Bowel Cancer Australia red meat
Australians consume an estimated average of 565 grams of red meat per week.  

Bowel cancer risk increases significantly when two or more alcoholic drinks are consumed per day.
Starting step: If you choose to drink alcohol, limit the amount.  
Modifiable Bowel Cancer Australia alcohol
Almost 1 in 5 Australian adults (18%) consume more than 2 standard drinks per day.

Body Fatness
Bowel cancer risk rises with increased body fatness, as marked by body mass index (BMI), waist circumference or waist-hip ratio.
During childhood and adolescence, be as lean as possible within the normal range of body weight.
From age 21, maintain body weight within the normal body mass index (BMI) range.
Starting step: Throughout adulthood, avoid weight gain and increases in waist circumference.
Modifiable Bowel Cancer Australia body fatness
Nearly 2 in 3 Australian adults (63%) are overweight or obese.

Smoking 40 cigarettes (two packs) per day increases the risk of bowel cancer by around 40% and nearly doubles the risk of bowel cancer death.
Starting step: Quit smoking and avoid exposure to tobacco smoke.

Modifiable Bowel Cancer Australia smoking
Almost 1 in 8 Australian adults (13%) smoke daily.