Can Weight Gain, Smoking Make Cancer More Likely to Come Back?
Platz and Joshu: Looking for lifestyle changes that can help keep cancer
So you’re a candidate for a radical prostatectomy, or maybe you’ve just had one. There is an excellent chance that your cancer will be cured. But what if there were some pill, some dietary supplement, something extra that could help you lower your odds of recurrence even more. Would you take it? Most men would, gladly.
Well, it’s not a pill, but intriguing work led by Hopkins scientists suggests that there is something that may help tip the scale — literally — away from cancer recurrence, and it has to do with gaining weight and smoking. A recent study found that men who gained five or more pounds near the time of their radical prostatectomy were twice as likely to have their cancer come back as men who maintained their weight. Men who were still smoking a year after their surgery were also more than twice as likely, compared to men who had never smoked or who had kicked the habit, to have their cancer return.
In this retrospective study, investigators surveyed more than 1,300 men who had undergone radical prostatectomy at Johns Hopkins to treat early-stage prostate cancer.
“ Taken together, these findings
suggest that by maintaining
a healthy weight and by not
smoking, men with prostate
cancer may not only help
themselves stay cancer-free, but
they can improve their overall
health and well-being.”
Most of these men were cured of their cancer, but in 106 men, cancer returned. Could it be, the scientists wondered, that lifestyle factors might play a role here? Were the men whose cancer returned doing anything differently? The men in the study were asked to fill out questionnaires, reporting on factors like their weight, diet, and smoking, and were followed for about seven years after surgery. They were also asked to recall how much they had weighed from five years before surgery to a year afterward.
“We found that men whose weight increased by more than about five pounds during this time period had an almost twofold higher risk of prostate cancer recurrence, as compared with men whose weight remained the same,” says Corinne Joshu, Ph.D., M.P.H., a postdoctoral fellow who, with epidemiologist Elizabeth Platz, Sc.D.,M.P.H., carried out the study, in collaboration with urologists Patrick Walsh, Misop Han, and colleagues at the National Cancer Institute and Duke University. “This was true even among physically active men.”
Although exercise certainly helps people lose weight, the key in this study seemed to be the weight change itself; the risk went up as the weight increased, and decreased with weight loss. On average, the men who had gained weight during this period reported that they’d gained about 10 pounds.
When the researchers looked for links between smoking and recurrence, they found that not only did smoking increase the risk of cancer returning, but that current smokers had a 25-percent higher risk of recurrence for every 10 pack-years smoked. (A pack-year is the number of packs of cigarettes a man smokes per day, times the number of years he has smoked.) “We found that men who keep smoking after being diagnosed with prostate cancer are more likely to have a recurrence — but that men who quit are not,” says Platz. “Taken together, these findings suggest that by maintaining a healthy weight and by not smoking, men with prostate cancer may not only help themselves stay cancer-free, but they can improve their overall health and well-being.”
This is not a definitive study, and more work is needed to confirm these findings, the researchers caution. For one thing, a larger number of men should be studied; for another, there are inherent difficulties in asking men to remember how much they weighed or how many cigarettes they smoked in the past. But it does raise questions to be pursued in other studies — including, from a basic science point of view, what biochemical pathways are activated or maintained by smoking, and how do these affect prostate cancer? What happens to these pathways when a man cuts calories, or packs on a few pounds? Another complicating factor is that, for reasons no one understands, PSA levels tend to be lower in heavyset men, so it may take longer for follow-up PSA tests to detect a change.
“The important thing here is that being overweight and smoking cigarettes are major health problems in our country,” says Platz. “More than two-thirds of Americans weigh more than they should, and 20 percent of adult men smoke. Right now, we can’t say for certain that these factors influence the recurrence of prostate cancer. But because they are so widespread, because they lead to premature death — and because they can be prevented — it makes sense for men who have had prostate cancer not to gain weight, and to stop smoking.”
These results were presented in April at the annual meeting of the American Association for Cancer Research, held in Washington, D.C.
The Bottom Line:
The vast majority of men who undergo radical prostatectomy are cured. In a recent study of more than 1,300 men, cancer returned in 106 men. What made the difference? It’s not certain yet, but a recent Hopkins study suggests that weight gain and smoking may be key factors.
Men who gained five or more pounds near the time of their radical prostatectomy were twice as likely to have their cancer come back as men who maintained their weight.
Men who were still smoking a year after their surgery were also more than twice as likely, compared to men who had never smoked or who had kicked the habit, to have their cancer return.