California Teachers Study

Smoking​

• Smoking may play a role in the development of breast cancer among CTS participants. Postmenopausal participants who were exposed to high levels of sidestream smoke (smoke from others’ tobacco products) had a small increased risk of breast cancer. Read more here.
   

• Compared with CTS participants who had never smoked, participants who smoked at the time of one CTS study (2013) had an approximately 30% increased risk of developing colorectal cancer. Participants who were former smokers appeared to have an elevated risk of colorectal cancer for up to 20 years after they ceased smoking.  Read more here.
   

• CTS participants who were smokers had an elevated risk of non-Hodgkin lymphoma. Participants who had never smoked but had been exposed to passive smoking (inhaling smoke from others’ tobacco products) also had an increased risk of developing non-Hodgkin lymphoma.  Read more here.​​

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• A number of reproductive and dietary factors correlate with different smoking exposures. For instance, both current and former smokers were more likely to experience menarche at an earlier age (<12 years) and bear no children compared with never smokers, and current smokers were also more likely to have their first child at a later age. Similarly, never smokers exposed to passive smoking were more likely to experience menarche at an earlier age, bear no children, or bear their first child at a later age compared with never smokers. Read more here.
   

• The incidence of breast cancer among current smokers was found to be higher than that of non-smokers. There was also no evidence found that non-smokers with household passive smoking exposure had a greater risk than non-smokers without the exposure. Read more here.
   

• Polycyclic aromatic hydrocarbons (PAH) are a class of chemicals released when coal, oil, wood, garbage, gas, and tobacco are burned. Several PAHs are suspected to be linked to cancer. Researchers used urine samples to measure 1-OPHG, a metabolite of the common PAH pyrene. They found that participants who self-reported long durations on the road (>=3 hours) compared with those with shorter times, participants who ate grilled, roasted, or broiled meat compared with those who ate meat cooked by other methods, and participants who smoked compared with those who didn’t had greater 1-OPHG levels. Furthermore, increased hours of exposure to secondhand smoking was found to be associated with greater 1-OPHG levels. Read more here.
   

• By pooling together data from 19 studies, researchers affirmed the association between both firsthand and secondhand smoking and increased risk of premenopausal breast cancer. Read more here.
   

• A 2019 study found second-hand smoking (SHS) exposure to be associated with a higher risk of type II diabetes among non-smoking California teachers. Greater SHS exposure has been previously suspected to be associated with increased waist circumference and BMI, which could explain much of the relationship between SHS and type II diabetes. Read more here.

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• Ovarian cancer subtypes have different risk factors. A 2018 study examined various subtypes and whether risk factors affected tumor aggressiveness. A first/single pregnancy was associated with a lower risk of highly aggressive disease compared with nulliparity (never having completed a pregnancy beyond 20 weeks), but no association was observed for subsequent pregnancies. For less aggressive disease, first and subsequent pregnancies were both associated with lower risk. Family history of ovarian cancer was only associated with the risk of less aggressive disease, while current smoking was found to be associated with increased risk of highly aggressive disease. Results were similar within the ranges of tissue types affected.  Read more here.
   

• Researchers found a higher rate of surgically diagnosed fibroids in African-American women than non-Latina white woman. The rate was also higher among premenopausal women, women who used postmenopausal therapy, and women who were overweight, drank alcohol or had a family history of fibroids. However, smoking and diabetes were found to be associated with a decreased risk of fibroids.  Read more here.