"The effect of secondhand smoke exposure on the association between active cigarette smoking and colorectal cancer."

Peppone LJ, Reid ME, Moysich KB, Morrow GR, Jean-Pierre P, Mohile SG, Darling TV, Hyland A.
Department of Radiation Oncology, University of Rochester Medical Center

Introduction

A 2010 article studies how second-hand smoke (SHS) from active cigarette smoking impacts colorectal cancer. Past studies have failed to find a link between smoking and colorectal cancer. Therefore, this study is significant because researchers determine an association between SHS and colorectal cancer, finding that long-term cigarette smoking is linked with increased colorectal cancer risk in males, but not in females. Although other studies may report an increased risk in individuals with long-term smoking exposure, not all support an association between smoking and colorectal cancer.

Methods

Subjects included 1,203 males and females, from 40 to 88 years of age. All subjects were patients with colorectal cancer, at Roswell Park Cancer Institute between 1982 and 1998. The control group included 2,406 individuals free of any neoplasm ranging in age from 40 to 86. SHS exposure was determined by comparing the odds ratios for each smoking variable in the sample and for those who said they had no SHS exposure (Peppone et al., 2010).

Results

Please click the following graphs for a clearer view.

Table 1 displays sociodemographic, lifestyle, and dietary variables of the controls. Cases and controls are alike in age, gender, education, income, alcohol consumption, fruit consumption, and vegetable consumption. Conversely, they are much more likely to have a higher BMI, live outside Western New York (WNY), be non-Caucasian, have a relative previously diagnosed with CRC, consume less cruciferous vegetables, consume more meat, and take less aspirin (Peppone et al., 2010).

Interestingly, Table 2 shows odds ratios which illustrate that there was no increase in colorectal cancer odds for females with the highest exposures of SHS.

Table 3 shows odds ratios which illustrate an increase in colorectal cancer odds for males who smoked more than 1 pack a day, smoked 46 or more pack-years, and smoked 20 or more pack-years before the age of 30. Colorectal cancer odds are more than doubled when compared to non-smokers with no secondhand smoke exposure. But the significant increase in colorectal cancer odds was noted for heavy, long-term smoking males when not accounting for SHS exposure (Peppone et al., 2010).

Discussion

The results show no increased risk of colorectal cancer in non-smoking females with exposure to seven or more hours a day of SHS. However, there seems to be a 58% increased risk in odds for non-smoking males exposed to seven or more hours of SHS everyday (Peppone et al., 2010). This may be because there were less females in the study, with a heavy smoking history. Limitations of this study include dishonesty in the questionnaires about SHS exposure. However, SHS exposure was assessed solely for the current frame in time, and not throughout adulthood (Peppone et al., 2010). Therefore, assessments may underestimate SHS exposure. Overall, further research will determine a direct association between SHS and colorectal cancer risk.

Conclusion

In this study, SHS exposure leads to an increased risk of colorectal cancer for all smoking variables. This is significant because this study proves that future studies must account for SHS exposure when determining a link between smoking and colorectal cancer.




References


Peppone L.J., Reid, M.E., Moysich, K.B., Morrow, G.R., Jean-Pierre, P., Mohile, S.G., Darling, T.V., Hyland, A. (2010). The effect of secondhand smoke exposure on the association between active cigarette smoking and colorectal cancer. Cancer Causes and Control, 21(8), 1247-1255.

How Fitness Relates to the Prevention of Chronic Diseases

Don’t they look so happy together? Wouldn’t you want to be able to bike with your significant other at their age? Well, you’ll be happy to know that physical activity promotes a longer life! In fact, inactivity increases all causes of mortality around the world. 

Physical activity is an important topic in Contemporary Health that relates well to chronic diseases. The ability to respond to regular physical demands with enough reserve energy to cope with sudden challenge, sums up physical fitness (Hales & Lauzon, 2009). Active living protects against many chronic diseases, such as heart disease, cancer, osteoporosis, and diabetes.

For example, cardiovascular disease (CVD) continues on as the first and foremost cause of premature death in Canada. Regularly active people are two times as likely to avoid CVD (Hales & Lauzon, 2009) – which means that something as simple as daily brisk walking for an hour, can greatly reduce the risk of CVD! Activity keeps the blood flowing, making blood clots less likely, thereby reducing chances of strokes or heart attacks (Harvard University, 2002). Other benefits include stronger heart muscles, effective blood pumping, lower hypertension, decreased heart rate, and increased high-density lipoproteins (HDL).

Studies have also shown that physical activity reduces the risk of colon cancer by 50% (Lee, Paffenberger, & Hseih, 1991). This is an astounding finding! Furthermore, physically fit men reduce risks of prostate and colon cancer, while fit women reduce risks of breast cancer. For postmenopausal women, more exercise lowers blood levels of estrogen (Women’s Health Weekly, 2002). Exercise has also been proven to lower risk of endometrial cancers.

In addition, as people age, their bones become denser. Peak bone mass is around 30 years of age. Weak bones are more common for those who don’t exercise (Hales & Lauzon, 2009). When bones lose mineral density, they become more prone to injury. Women especially, have less dense bones to begin with, and bone loss increases after menopause.

 Another chronic disease whose risk increases as people age, is diabetes. About one in 18 Canadians has been diagnosed with diabetes (Hales & Lauzon, 2009). Physical activity improves insulin sensitivity and reduces weight, thereby lowering the risk of diabetes.


As you can see, there are numerous benefits to regular physical activity – many of which can help in preventing chronic diseases. Most people exercise to look good for others, but health can be another great incentive to go for a run on the treadmill, or enjoy a sunny day outside cycling. As with many things (such as learning languages), starting young will provide much more benefit than starting later. Exercise today, keep your body fit, and you’ll be rewarded a long, healthy life!







References

Exercise lowers levels of blood estrogen. (2002, August 8). Women’s Health Weekly, 10.

Hales, D., & Lauzon, L. (2009). An Invitation to Health. Toronto: Nelson Education Ltd.

Harvard University. (2002). Heart beat – Activity keeps the blood flowing. Harvard Heart Letter, 12(11).

Lee, I.-M., Paffenberger, R.S. Jr., & Hseih, C.-C. (1991). Physical activity and risk of developing colorectal cancer 
          among college alumni. Journal of the National Cancer Institute, 83, 1324-29.