Cancer: Why did you get cancer and not someone else?

On August 3, 2022, the Population Science Division of the American Cancer Society (ACS) published a research study entitled "Key risk factors for the relative and absolute 5-year risk of cancer to enhance cancer screening and prevention" in Cancer.
Results (Figure 1) [1]
.
The findings indicated that older age and smoking were the two most important risk factors associated with the 5-year relative and absolute risk of developing any cancer
.

Figure 1 Research results (source: [1])

The study included participants in two prospective observational cohort studies of ACS: the Cancer Prevention Study-II Nutrition Cohort (CPS-IINC, n=184183) and the Cancer Prevention Study-3 (CPS-3, n=303682), These studies were conducted between 1992-2006 and 1993-2013, respectively
.
Two cohorts were used to identify risk factors associated with an absolute risk of >2% for any cancer over 5 years
.
In total, 429,991 participants with no personal history of cancer were followed up for up to 5 years of cancer
.
Multivariate Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals for the association
.
Using these hazard ratios, individualized coherent absolute risk estimates were used to calculate absolute risk by age
.

turn out: 

Most commonly diagnosed cancer in 5 years: breast cancer in women and prostate cancer in men

A total of 15,226 invasive cancers (7730 males; 7496 females) were reported within 5 years of enrollment
.
Of these cancers, 57% of men and 50% of women were cancer types with established screening paradigms, with the most commonly diagnosed cancers: breast cancer in women and prostate cancer in men
.
Among the cancers not screened for at the time of enrollment in both cohorts, the most frequently diagnosed cancers were uterine cancer in women and lung cancer in men
.

Smoking is the strongest factor associated with cancer risk

Current smoking had the strongest association of all potential risk factors with cancer risk (HR, 1.
63; 95% CI, 1.
51-1.
77 for men; HR, 1.
55; 95% CI, 1.
43-1.
68 for women)
.
In men, statistically significant associations were also observed with family history of cancer, alcohol intake, red meat intake, and physical activity; in women, BMI (Body mass index), type 2 diabetes, cancer family History, current estrogen and progesterone use of exogenous postmenopausal hormones, hypertension, hysterectomy, parity, and tubal ligation were statistically significant
.

5-year cancer risk among smokers: 29% for men aged 50 or older, 25% for women

Regardless of risk factor, nearly all men and women aged 50 years or older have an absolute risk of ≥2% for developing any cancer over a 5-year period, up to 29% for men and 25% for women for certain risk factors
.
Furthermore, within a given age range of 5 years, the absolute rate difference was approximately 2.
5-fold for males and approximately 4-fold for females according to the risk factor profile
.
Among men younger than 50 years, the risk was 2.
7% among male current smokers between the ages of 45 and 50 who were concurrently exposed to all other risk factors (heavy drinkers with a family history of cancer, unrestricted red meat intake, and inactivity) ); in women, the absolute risk of recent smokers combined with various other risk factors was ≥2% from age 35 to 40 years
.
In addition, among some women who had recently smoked, based on other risk factors, the absolute risk was as high as 3.
8% between the ages of 40 and 45 and as high as 5.
8% between the ages of 45 and 50
.

5-year cancer risk in non-smokers: <19% for men over 50 years old, ≥2% for women aged 45-50 years

In men who have never smoked or quit smoking for ≥30 years, a family history of diabetes and cancer increases the risk of cancer
.
Among women who had never smoked or quit smoking for ≥30 years, BMI, family history of cancer, and parity were most strongly associated with cancer risk, followed by hypertension, current combined use of postmenopausal hormones, hysterectomy, and tubal ligation
.

The absolute risk did not exceed 2% for any risk factor for men under 50 who had never smoked or had chronically smoked
.
At older ages (up to 80 to 85 years), the absolute risk never exceeded 19% for men who had never smoked or had chronically smoked
.
Among women who had never smoked or quit smoking for ≥30 years, the absolute risk was ≥2% for nearly all risk factors starting at age 45 to 50 years, suggesting that nonsmokers bear the risk for other risk factors
.
At older ages (up to 80 to 85 years), the absolute risk for women who had never smoked or had been chronically smoked never exceeded 17%
.

The study found that after age 50, the most important risk factor for developing cancer within 5 years was smoking history
.
For never-smokers (or those who quit a long time ago), BMI and family history of cancer had the greatest impact on cancer development
.
In addition to age, clinicians should consider smoking history, BMI, and family history of cancer when helping patients determine whether they may benefit from cancer screening and preventive interventions
.

The strength of this study is its large scale, detailed data, and coverage of a broad range of risk factors, including those included in previous assessments of population-attributable risk
.
Limitations include a lack of data on every risk factor included in disease risk, or all factors a primary care physician might want to consider; another limitation is that there may be varying degrees of random systematic error in measuring different exposures (e.
g.
This does not significantly alter the results, as previous studies of the CPS cohort have demonstrated predictive validity for all exposures; in the end, there were only 860 cancers (5% of the total) in non-white participants, therefore, it was not possible to examine individual race/ Risk of ethnic group stratification
.

References:

[1]Patel AV, Deubler E, Teras LR, et al.
Key risk factors for the relative and absolute 5-year risk of cancer to enhance cancer screening and prevention.
Cancer.
2022 Aug 3.
doi: 10.
1002/cncr.
34396.
Epub ahead of print.
PMID: 35920750.