With two-thirds of Americans now overweight, we can probably expect more obesity-related cancers. But on the brighter side, weight problems are extremely treatable, even preventable. So to the extent overweight is contributing to cancer, this is one risk factor we may actually have some real control over.

Just how we go about getting that control appears to be critical, though. Even among the most motivated of people, we see that very few are successful in independent efforts to lose weight, even if their life depends on it. And among cancer patients, it clearly does.

Consider some of the numbers: breast cancer in women increased by 52 percent from 1973 to 1998. Part of that increase can be accounted for by better detection, because mammography is much more available than it was 30 years ago. But use of post-menopausal estrogen supplements has also become routine, and these have been clearly linked to cancer in women.

But in that same period, incidence of breast cancer among men increased by 26 percent, and that's without the ingested estrogen and without the extra detection offered by mammography, since men typically don't pursue that procedure.

So what else is going on? Experts say the increase in breast cancer in both sexes seems to closely track the increase in American obesity, giving rise to the theory that the obesity crisis may actually be to blame for the boom in breast cancer.

Obesity has been shown to have a clear relationship with some cancers, but not with others. For instance, there does not appear to be any correlation between overweight and prostate cancer in men. Or sometimes, the relation is clear, but the reasons aren't. Hence, researchers are looking at whether acid reflux in overweight people might account for their greater incidence of esophogeal cancer.

But with breast cancer, there is at least one known culprit: all that excess estrogen. Fatty tissue produces estrogen, in both men and women.

Studies of menopausal women make the case most clearly. Before menopause, the ovaries are the primary source of estrogen. But after menopause, when the ovaries have retired from that duty, fatty tissues are the main estrogen source.

Among postmenopausal women, estrogen levels are 50 to 100 percent higher in heavy women, compared to those of healthy weight. Similar ratios are found among men.

And when estrogen-sensitive tissues get more estrogen exposure, that leads to more growth of estrogen-responsive breast tumors.

Researchers figure that between 11,000 and 18,000 breast cancer deaths per year could be avoided in American women over age 50, if they could maintain a healthy body weight throughout their adult lives. There are no similar guesstimates for men, because while breast cancer is a growing problem for men, there is little research on mortality rates among males, and it is still less of a concern than heart disease or prostate and colon cancer.

But obesity puts men at higher risk for these diseases, as well, so the imperative is to drop that excess weight, or at least some of it. There's abundant evidence that even a minor weight loss reaps huge rewards for health. So how do you do it?

It's tough, especially if you're an older person, and the average age of diagnosis for breast cancer is 62 among women, and 67 among men.

Motivation counts, but the research shows that it's not enough. People need help. For instance, who would be more motivated to lose weight than a heavy person who had already survived cancer?

An overweight survivor has a double whammy when it comes to risk of recurrence, but a study published earlier this year in Obesity Research said that even among that motivated group, people left to their own devices, or those who only had a group program did not achieve much weight loss.

This is no surprise to those of us who have treated obesity for years. We see people who have tried diet after diet, joined gym and club and fellowship alike, all to no avail. But when they are treated with a comprehensive diet and lifestyle modification program that has been designed specifically for them, things change.

In this latest study, the researchers were pretty unequivocal, concluding that "for breast cancer survivors to lose weight to reduce risk factors, intervention is necessary. Of the different intervention regimens, individualized counseling combined with attending weekly ... meetings was most effective...."

When you're facing a chocolate eclair, death is perhaps too abstract an idea, even if you've only narrowly escaped it. Without some real retraining, it's hard to equate even the greasiest burger with a lethal tumor. But professional support makes all the difference.

For instance, I've been tracking insulin levels in weight management patients for years, because we know that high insulin levels indicate a metabolic abnormality that leads to diabetes and weight gain. Now recent research shows that elevated insulin levels are also a risk factor for breast cancer recurrence.

Yet very specific changes in lifestyle and diet can significantly reduce insulin levels in days to weeks, immediately reducing those disease risks. The disembodied threat of disease is sometimes hard for people to get their arms around, but when patients can look at their lab results and see how their behavioral changes directly affect their blood chemistry, it hits home.

What happens to patients' bodies on the inside as they lose weight is more important than the changes they get on the outside, but even at the best health clubs or peer support groups, they won't have an opportunity to see that.

It's inspiring to see how people embrace a fitness and weight-loss program when they have more than just a bathroom scale to tell them that it's working. Consistent and reliable guidance is essential because nobody goes from obese to healthy overnight. It takes time.

But cancer takes time, too, so the race is on. With the proper help, this is a race both men and women have great odds of winning.

THROUGH THICK & THIN

Breast cancer is a growing risk for both men and women, and it's a cancer for which the obesity link has been clearly established. Fat produces excess estrogen; excess estrogen produces breast cancer. And in the reverse, weight loss reduces cancer risk. The data are clear, but it doesn't make the task any easier. What does make it easier, and more successful, is professional help---and the sooner the better.

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Caroline J. Cederquist, M.D. is a board certified Family Physician and a board certified Bariatric Physicians (the medical specialty of weight management). Dr. Cederquist is the founder of formerly Diet To Your Door, a home diet delivery program that specializes in low calorie gourmet food that is delivered to your home or office. Bistro MD serves as culmination of Dr. Cederquist's expertise and experience in the world of medical weight loss.