A major new analysis has entered the lifestyle vs. luck fray via JAMA Oncology, its authors having concluded that changes in lifestyle can ward off most cancers and that primary prevention ought to remain a priority for cancer control.
Citing and, in effect, challenging a recent study suggesting that most cancer is caused by random mutations in cell divisions, Mingyang Song, MD, ScD, and Edward Giovannucci, MD, ScD, both affiliated with the Harvard T.H. Chan School of Public Health, describe how they designed their analysis to estimate the proportion of cancer incidence and mortality among white U.S. patients that can be potentially prevented by lifestyle modification.
They looked at all cancers except skin, brain, lymphatic, hematologic and nonfatal prostate malignancies, conducting a prospective-cohort study of data on more than 135,000 individuals in the Nurses’ Health Study, the Health Professionals Follow-up Study and national cancer registries.
Song and Giovannucci defined a healthy lifestyle pattern as nonsmoking or smoking cessation with a history of less than five pack years; no or moderate alcohol drinking (no more than one drink per day for women, no more than two drinks per day for men); body-mass index of at least 18.5 but lower than 27.5; and weekly aerobic physical activity of at least 75 vigorous-intensity or 150 moderate-intensity minutes.
Subjects meeting all four of these criteria made up the low-risk group, and all others went into the high-risk group.
Comparing the incidence and mortality of total and major individual cancers between the two groups, Song and Giovannucci calculated population-attributable risk (PAR).
A total of 16,531 women and 11,731 men had a healthy lifestyle pattern, placing them in the low-risk cohort, and the remaining 73,040 women and 34,608 men made up the high-risk cohort.
The study’s key findings:
- Total cancers per 100,000 women occurred at the rate of 463 in low-risk women vs. 618 in high-risk women.
- Total cancers per 100,000 men occurred at the rate of 283 in low-risk men vs. 425 in high-risk men.
- With a few exceptions, PARs for mortality were similar to PARs for incidence.
Among their study’s limitations, the authors acknowledge the inclusion of only white patients in their PAR estimates.
“However, all of the considered factors have been established as risk factors in diverse ethnic groups, although there could be differences in the magnitudes of the associations,” they write.
In their discussion, Song and Giovannucci conclude that “a substantial proportion of cancer cases and even more deaths among U.S. white individuals might be prevented by quitting smoking, avoiding heavy alcohol consumption, maintaining a BMI between 18.5 and 27.5, and exercising at a moderate intensity for at least 150 minutes or at a vigorous intensity for at least 75 minutes every week. These findings reinforce the predominant importance of lifestyle factors in determining cancer risk.”