It is known that smoking causes lung cancer and heart disease. Does smoking play a role in causing colorectal cancer (CRC)? While there are well known genetic causes for CRC, most CRCs in the general population are not genetically linked. Colonic adenomatous polyps are precursors to CRC; the larger the polyp, the higher the chance that it will have malignant potential. Colorectal polyps can be pedunculated or flat. Pedunculated polyps are easier to visualise and flat polyps can be missed easily during colonoscopy, especially when they are small. If adenomatous polyps are left untreated, they will turn into colon cancer with time. Recently, the American College of Gastroenterology published guidelines suggesting that smokers with a history of > 20 pack years may need screening for CRC earlier than their non-smoking counterparts. Are smokers at higher risk of developing colon polyps?

Researchers from Seoul National University Hospital studied 5254 asymptomatic subjects undergoing screening colonoscopy (J Gastroenterol Hepatol 2010; 25: 519 – 525). They were split into 3 groups aged 30 – 39 years, 40 – 49 years and 50 – 59 years. The prevalence of overall adenomas was 10.4% in the 30- 39 years age group, 22.2% in the 40 – 49 years age group and 32.8% in the 50 – 59 years age group. The prevalence of advanced adenoma was 0.7%, 2.7% and 4.1%, respectively. Male sex, current smoker and family history of CRC were independent predictors of advanced adenoma in the 40 - 49 years group. The risk of developing advanced adenoma in smokers is increased by 58%.

In another study from the University of Connecticut, 600 asymptomatic patients presenting for CRC screening were studied with high-definition colonoscope to detect flat adenomas (Gastrointest Endosc 2010; 71: 1234 – 1240). Of these 600 patients, 313 were non-smokers, 115 were heavy smokers (10 or more pack years and still smoking or had quit within 10 years) and 172 were low-exposure smokers (< 10 pack years or had quit more than 10 years ago). Heavy smoking increased the risk for flat adenomas of any size by 153%. The risk for flat adenomas of 6 mm or more was increased 284% in heavy smokers. Heavy smoking increased the risk of advanced flat adenomas by 181%. How heavy you smoke also increased the risk of developing flat adenomas. The risk was increased 128 % in those with > 30 pack years of smoking compared to those with < 30 pack years.

Smoking is known to cause many health problems. It is also considered to be an anti-social behaviour by many. Yet the number of smokers worldwide is increasing, especially in developing and under-developed countries. The mind boggles!

Recently, a lady from Malaysia consulted me for a second opinion as she had been diagnosed with stage IV pancreatic cancer. Apart from a history of epigastric discomfort, early satiety and slight loss of weight, she felt fine. The CT scan showed a locally advanced pancreatic cancer with metastases to the liver. The family wanted to know why she developed the cancer. Was it something she had eaten, drunk or something she had come into contact with?

Researchers from the National Cancer Institute, USA, studied the link between 5 lifestyle factors and the risk of pancreatic cancer in 450,416 participants in the National Institutes of Health-AARP Diet and Health Study (Arch Intern Med 2009; 169: 764 – 770). During 1995 – 1996, these participants completed a baseline frequency questionnaire eliciting diet and lifestyle information and were followed up through 31^st December 2003. The participants were scored on 5 modifiable lifestyle factors as unhealthy (0 points) or healthy (1 point), receiving 1 point each for non-smoking, limited alcohol use, adherence to the Mediterranean dietary pattern, body mass index (BMI, ≥ 18 and < 25) and regular physical activity. A combined score of 5 meant most healthy and a score of 0 meant least healthy.

The distribution of lifestyle scores was 1.5%, 10.7%, 27.8%, 31.3%, 21.1% and 7.6% for scores of 0, 1, 2, 3, 4 and 5, respectively. Those with higher scores tended to be older, were less likely to be African-American and had a higher educational level. Having a combined lifestyle score of 5 was associated with a 58% risk reduction for pancreatic cancer. Non-smoking and normal BMI were associated with a statistically significant reduction of pancreatic cancer risk. Among the 5 risk factors, non-smoking had the higher population-attributable risk of 14%; that is 14% of cases would have been prevented if all participants were non-smokers.

Among cancers, pancreatic cancer incidence among men and women is 9^th and 10^th respectively. However, the mortality rate is worse compared to other more common cancers and it ranks 4^th among men and women. It carries a much poorer prognosis because the pancreas lies deep at the back of the abdominal cavity. It tends to grow to a more advanced stage before giving symptoms. In order to reduce the burden of this disease we should think more in terms of prevention. The simplest preventative measures should start with what we do and what we eat / drink. We need to modify our lifestyle habits in order to reduce our risk for pancreatic cancer.

As the saying goes - you reap what you sow!

Physical inactivity is associated with increased incidence of obesity, diabetes mellitus, cardiovascular diseases, osteoporosis and cancer. Consequently, the American Heart Association, the American College of Sports Medicine and the US Department of Health and Human Services recommended that adults engage in at least 30 minutes of moderate physical activity preferably on all days of the week. In a study, published in 2007, by the National Institute of Health, involving 252, 925 individuals, adherence to the above physical activity guidelines resulted in a 50% reduction in the overall mortality risk (Arch Intern Med 2007; 167: 2453 – 2460). Having been stuck in a sedentary lifestyle in one’s younger days, will increased exercise level later in life reduce one’s mortality rate?

Researchers from Uppsala University and Karolinska Institutet studied 2322 men aged 49 – 51 years at baseline and followed them up for more than 35 years (BMJ 2009; 338: b688). These men were studied again at ages 60, 70, 77 and 82 years. At baseline almost half of the men reported a high level of physical activity (at least 3 hours of recreational sports or heavy gardening a week), 36% reported medium activity (walk or cycle for pleasure) and 15% were sedentary (spending most of the time reading, watching TV and going to the cinema). The study found that the relative mortality rates were highest among sedentary men and lowest among the most active men. When converted into differences in remaining life expectancies from age 50, high physical activity men were expected to live 3.8 years longer than sedentary men and 1.8 years longer than medium physical activity men. Men who increased their physical activity to a high level at 50 and maintained it till age 60 had the same mortality rate as the men who had been at high physical activity before entering the trial. In other words, if you adopt a high physical activity lifestyle at 50, by the time you reach 60 you will have ‘caught up’ and have the same mortality rate as someone who has embraced a high physical activity lifestyle before 50 years of age. After > 10 years of follow-up, the mortality rate in men who had increased their physical activity to a high level both from a medium or low level had halved. After > 10 years of follow-up, compared to current smokers, smoking cessation was associated with a 40% reduction of mortality rate. Men who never smoked had a 60% lower mortality rate than current smokers.

To those middle aged men who smokes and exercise little, the excuse that ‘The damage is done. It is too late for me to stop smoking and start exercising.’ may seem a bit flimsy now. You might wish to heed the saying ‘It is never too late to try’.