Friday, March 21, 2014

Does Surviving Breast Cancer Lead to Obesity?

sharma-obesity-mammographyWe have long recognised obesity as significant risk factor for post-menopausal breast cancer  but emerging data suggests that surviving cancer may in itself promote weight gain.

Thus, a study by Rebecca Sedjo and colleagues, in a paper published in the Journal of Cancer Survivorship, notes significant weight gain in 665 overweight and obese women within five years of surviving breast cancer.

The average weight gain over five years was 4.5% with almost half the participants gaining significantly more weight.

Younger women and those with lower BMIs were more likely to gain significant amounts of weight over time.

Pharmacological treatment was also an important predictor of weight gain, with women treated with selective estrogen-receptor modulators twice as likely to gain weight compared to women prescribed aromatase inhibitors.

Clearly, post-diagnosis weight gain is common in breast cancer survivors and is influenced by a complex set of factors including age, ethnicity, weight, smoking status, time elapsed since diagnosis, and endocrine-modulating therapy.

It appears that exploration of effective strategies to prevent this weight gain or provide obesity management strategies to breast cancer survivors are long overdue.

Edmonton, AB

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Thursday, July 25, 2013

Clinical Management of Obese Patients With Cancer

Metastasizing Cancer Cell

Metastasizing Cancer Cell

Obesity is a risk factor for many cancers. But even if this were not the case, the increase in the number of people living with obesity means that more obese people will be diagnosed with cancer than ever before.

The many complex issues facing oncologists in managing their obese cancer patients are nicely summarized and reviewed in a paper by Wenjing Tao and Jesper Lagergren from the Karolinska Institute, Stockholm, Sweden, in a paper published in Nature Reviews Clinical Oncology.

As the authors point out, not only does a large body of epidemiological evidence link obesity to increased cancer incidence, but there is also evidence suggesting poorer survival in obese patients with cancer.

There are also a number of important challenges related to diagnosis including reduced participation of obese individuals in cancer screening programs, lower tumour-marker expression and problems with medical imaging among obese individuals.

Excess body weight also alters pharmacokinetics of chemotherapy and hormone therapy and precision of radiotherapy might be adversely affected by greater skin motility and increased motion of internal organs.

Obese patients can also face higher risks of complications with surgery and recovery times may be affected.

Finally, the authors discuss the importance of sarcopenic obesity and  the problem of excess weight gain associated with cancer survival, both of which can affect long-term outcomes.

But, as the authors conclude,

“Although the number of obese patients with cancer is rapidly growing, there is a lack of evidence-based clinical guidelines specifically addressing diagnosis and treatment for these patients.”

Kananaskis, AB
ResearchBlogging.orgTao W, & Lagergren J (2013). Clinical management of obese patients with cancer. Nature reviews. Clinical oncology PMID: 23856746



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Friday, April 5, 2013

Muscle Loss Predicts Outcomes in Cancer

scaleRegular readers will be quite familiar with the limited utility of BMI in predicting health status. The same appears to be true regarding the use of BMI in patients with cancer cachexia.

In a paper just published in the Journal of Clinical Oncology, Lisa Martin and colleagues from the University of Alberta studied around 1,500 patients with various stages of lung or gastrointestinal cancer presenting with a wide range of BMI (17% obese, 35% overweight, 36% normal weight, and 12% underweight).

Patients in all BMI categories varied widely in weight loss, muscle index, and muscle attenuation (measured by CT).

Irrespective of BMI, high weight loss, low muscle index, and low muscle attenuation were independently prognostic of survival.

Compared to a survival model containing conventional covariates (cancer diagnosis, stage, age, performance status), a model ignoring these variables but including only BMI, weight loss, muscle index, and muscle attenuation proved a far better predictor of patient survival.

Patients who had higher weight loss and lower muscle indicators survived 8.4 months, regardless of whether they presented as obese, overweight, normal weight, or underweight, in contrast to patients who had none of these features, who survived 28.4 months.

From these finding the authors conclude that, regardless of BMI, cancer patients presenting with involuntary weight loss, muscle depletion and muscle attenuation share the poorest prognosis.

Thus, the authors note that,

“Our findings provide evidence in support of the proposed international consensus definition of cancer cachexia as a multifactorial syndrome defined by an ongoing loss of skeletal muscle mass with or without loss of fat mass.”

Once again, simply stepping on a scale appears to be a rather limited measure of health.

Edmonton, Alberta

ResearchBlogging.orgMartin L, Birdsell L, Macdonald N, Reiman T, Clandinin MT, McCargar LJ, Murphy R, Ghosh S, Sawyer MB, & Baracos VE (2013). Cancer Cachexia in the Age of Obesity: Skeletal Muscle Depletion Is a Powerful Prognostic Factor, Independent of Body Mass Index. Journal of clinical oncology : official journal of the American Society of Clinical Oncology PMID: 23530101


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Monday, September 17, 2012

Obesity Does Not Increase Mortality in Gastric Cancer

One of the consistent findings in the medical literature is the fact that although excess weight is associated with an increased risk for a wide range of medical problems (including the earlier onset of such complications), once people have these problems, excess weight appears to be either ‘protective’ (the so-called obesity ‘paradox’) or have little influence on long-term outcomes.

Thus, a study by Kai Bickenback and colleagues from the Memorial Sloan-Kettering Cancer Center, New York, NY, published in the Annals of Surgical Oncology, failed to find an impact of obesity on long-term survival of patients with gastric (stomach) cancer.

In their study, the researchers examined dat from about 1,800 patients who underwent curative intent resection for gastric carcinoma from 1985 to 2007.

Overall, there was no difference in survival between overweight or obese and normal weight patients.

However, overweight patients did have more proximal tumors and a lower tumor (T) stage at surgery.

Overweight and obese patients also had about twice the rate of wound infections and anastomic leaks than normal weight patients.

In multivariate logistic regression analyses, higher BMI, total gastrectomy, and use of neoadjuvant chemotherapy were all associated with increased wound infection and anastomotic leaks.

Thus, the authors note that although peri-operative complications may be more common in overweight and obese patients undergoing surgery for gastric cancer, their survival rates are no worse than those of normal weight individuals.

Obviously, given the higher peri-operative complication rates, costs for hospital stay and doctor visits may be higher in the overweight and obese patients (not analysed in this paper) – however, this should certainly not prove a barrier to providing the same care to overweight and obese patients with gastric cancer as one would to normal-weight individuals with this unfortunate condition.

Edmonton, Alberta

photo credit: Defence Images via photo pin cc

ResearchBlogging.orgBickenbach KA, Denton B, Gonen M, Brennan MF, Coit DG, & Strong VE (2012). Impact of Obesity on Perioperative Complications and Long-term Survival of Patients with Gastric Cancer. Annals of surgical oncology PMID: 22976377

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Thursday, May 24, 2012

Calorie Restricted Diet Decreases Breast Cancer Biomarkers in Post-Menopausal Women

Although, much of the discussion around the health risks of obesity tends to focus around diabetes and heart disease, it is important not to forget that in women, excess weight is closely linked to the risk for post-menopausal breast cancer (by far the most common form of breast cancer).

Now, a team of researchers led by Kristin Campbell from the University of British Columbia, Vancouver, in a paper published in the Journal of Clinical Oncology, shows that weight loss achieved by calorie restriction and exercise can significantly reduce circulating levels of the sex-hormones implicated in the development of post-menopausal breast cancer.

The single-blind, 12-month, randomized controlled trial was conducted in 50 to 75 year-old women with a BMI greater than 25, who were assigned to one of three intervention groups: (1) reduced-calorie weight loss diet (“diet”; n = 118), (2) moderate- to vigorous-intensity aerobic exercise (“exercise”; n = 117), (3) combined reduced-calorie weight loss diet and moderate- to vigorous-intensity aerobic exercise (“diet + exercise”; n = 117), or (4) control (n = 87).

The weight loss diet intervention was a modification of the dietary component of the Diabetes Prevention Program36 and the Look AHEAD (Action for Health in Diabetes) lifestyle intervention programs, with a goal of daily energy intake of 1200 to 2000 kcal/d based on baseline weight, less than 30% daily energy intake from fat, and a 10% reduction in body weight by 6 months with maintenance to 12 months.

The exercise intervention goal was  45 minutes of moderate- to vigorous-intensity aerobic exercise, 5 days per week (225 minutes/wk). Each week, participants attended three monitored exercise sessions at the study facility and two at home. The program progressed to the maintenance target of 70% to 85% maximal heart rate for 45 minutes by week. Activities with four or more metabolic equivalents,38 such as brisk walking, were counted toward the prescribed exercise target.

These interventions resulted in significant weight loss at 12 months: diet alone and diet + exercise resulted in about 11-12 Kg weight loss, exercise alone resulted in about 3.5 Kg weight loss, the control group lost no weight.

Compared with controls, estrone decreased 9.6% with diet, 5.5% with exercise, and 11.1% with diet + exercise.

Estradiol decreased 16.2% with diet, 4.9% with exercise, and 20.3% with diet + exercise.

Sex hormone-binding globulin (SHBG) increased 22.4% with diet and 25.8% with diet + exercise.

Free estradiol decreased 21.4% with diet and 26.0% with diet + exercise.

Free testosterone decreased 10.0% with diet and 15.6% with diet + exercise.

Thus, weight loss significantly lowered serum estrogens and free testosterone, findings that support the notion that weight loss can likely reduce risk for breast caner by lowering the exposure to breast cancer biomarkers.

It may be worth recalling, that surgical weight loss studies have shown a remarkable 60% decrease in cancer mortality, including a reduction in breast cancers.

Thus, the potential of obesity treatment as a means to reducing breast cancer risk should not be underestimated.

Philadelphia, PA

ResearchBlogging.orgCampbell KL, Foster-Schubert KE, Alfano CM, Wang CC, Wang CY, Duggan CR, Mason C, Imayama I, Kong A, Xiao L, Bain CE, Blackburn GL, Stanczyk FZ, & McTiernan A (2012). Reduced-Calorie Dietary Weight Loss, Exercise, and Sex Hormones in Postmenopausal Women: Randomized Controlled Trial. Journal of clinical oncology : official journal of the American Society of Clinical Oncology PMID: 22614972


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In The News

Diabetics in most need of bariatric surgery, university study finds

Oct. 18, 2013 – Ottawa Citizen: "Encouraging more men to consider bariatric surgery is also important, since it's the best treatment and can stop diabetic patients from needing insulin, said Dr. Arya Sharma, chair in obesity research and management at the University of Alberta." Read article

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