ATLANTA — Cancer can be the unfortunate end result of numerous dietary and lifestyle choices, but a new study has identified the two most influential factors. Researchers at the American Cancer Society say aging and smoking are the two most important risk factors when determining a person’s relative and five-year risk of developing any type of cancer.
Besides the big two, the study also notes doctors should consider excess body fatness, familial history of cancer, and a number of other factors when determining if patients may benefit from enhanced cancer screening or prevention interventions.
“Single cancer type-specific screening recommendations are based on risk factors for that specific type of cancer,” says lead study author Dr. Alpa Patel, senior vice president, population science at the American Cancer Society, in a media release. “Our findings are encouraging as we are working to define subgroups in the general population who could benefit from enhanced cancer screening and prevention.”
These findings are based on two ACS prospective studies: Cancer Prevention Study-II Nutrition Cohort and Cancer Prevention Study-3. Researchers analyzed those earlier projects in an attempt to identify any risk factors with a link to a greater than two-percent absolute risk of any cancer within five years.
Cancer risk increases after age 50
In total, researchers examined 429,991 U.S. participants, all with no prior personal history of cancer. The team tracked each person for up to five years. Study authors made use of Multivariable Cox proportional hazards models to estimate hazard ratios (HR) and 95-percent confidence intervals for association. Utilizing the HRs, researchers used individualized Coherent Absolute Risk Estimation to calculate absolute risks by age.
Results show 15,226 invasive cancers were diagnosed within five years of enrollment. The multivariable-adjusted relative risk of any cancer was strongest among current smokers in comparison with “never-smokers.”
For men specifically, alcohol habits, family history of cancer, red meat consumption, and physical inactivity also displayed a link to cancer risk. Among women, the team named body mass index (BMI), type 2 diabetes, hysterectomy, parity, family history of cancer, hypertension, tubal ligation, and physical inactivity as cancer risk factors.
As for aging, the absolute five-year risk exceeded two percent among nearly every participant older than 50. This was also true for some participants younger than 50 who were current or former smokers, had a BMI greater than 25, or had a first-degree family history of cancer. Absolute five-year risk levels reached as high as 29 percent in men and 25 percent in women.
“As we consider the possibility that future tests may be able to identify several types of cancer, we need to begin understanding who is most at risk for developing any type of cancer,” Dr. Patel concludes. “These types of data are not widely available, but necessary to inform future screening options, such as blood-based multi-cancer early detection tests that could help save lives.”
The study is published in the journal Cancer.