The Diabetes-Cancer Connection: Breast Cancer

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In September 2010, AICR published “The Diabetes-Cancer Connection” paper discussing the research on the link between these two diseases and how health professionals can counsel patients on lifestyle changes to lower risk of both.

Now several studies in the Journal of Clinical Oncology show how both type 2 diabetes and insulin resistance negatively impact prognosis in breast cancer patients. Those with type 2 diabetes or insulin resistance do not fare as well as breast cancer patients who did not have those conditions.

An accompanying editorial discusses two simple procedures that health care providers should do for patients with breast cancer to improve outcomes.

1.            Measure waist circumference. This simple measure may point to metabolic syndrome associated with type 2 diabetes and related risk factors.

2.            Measure HOMA index (indicator of insulin resistance).

The authors of the editorial explain that with these measures, health care providers would be able to individualize a patient’s treatment to include diet and physical activity programs that are known to improve survival for many.

The editors give a call to action to integrate care of these two diseases:

“The time has come to overcome the conventional tunnel vision that results in two diseases being treated by separate clinicians, and to move towards a comprehensive approach that ideally integrates oncologists, internists, nutritionists, and other health care professionals in an attempt to improve breast cancer prognosis in a significant proportion of patients.” Read more… “The Diabetes-Cancer Connection: Breast Cancer”

Weight Lifting May Help Breast Cancer Survivors

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First, there was the news that weightlifting may help breast cancer survivors who already have the common – and painful – condition called lymphedema. Now the same team of researchers has found that weightlifting may play a key role in preventing the condition.

The research is a big deal because traditionally, breast cancer survivors at risk of lymphedema were advised to avoid weight-bearing exercises or even carrying children or heavy bags in the fear they would get the condition. But avoiding weightlifting means women can not reap the many benefits of weight-lifting exercises and it may keep them from exercise in general, which research suggests can prevent recurrence and improve survival.

The study was published online in the Journal of the American Medical Association. Here is the abstract.

The lead researcher of the study was Kathryn H. Schmitz, PhD, MPH of the University of Pennsylvania, who was one of the presenters at AICR’s Annual Research Conference in 2009. At the conference Dr. Schmitz spoke about strategies to promote physical activity among cancer survivors.

In this brief video clip from the AICR conference, Dr. Schmitz offers direction and resources for survivors at risk of lymphedema or women who already have it.

For the JAMA study, Dr. Schmitz and her colleagues randomly split 154 breast cancer survivors without lymphedema into two groups: one group lifted weights and the other did not. The weight lifters were supervised for the first 13 weeks of the study. At the end of one year, fewer women in the weightlifting regimen developed the condition compared to the non-weight lifters (11% and 17%, respectively).

Among women who had five or more lymph nodes removed during surgery, the impact of the weightlifting intervention was even more.

Lymphedema occurs when the normal flow of lymph fluid becomes blocked and causes limbs to swell. During treatment for breast cancer, the lymph nodes (which carry the fluid) are harmed or removed. You can find out more about lymphedema at the the National Lymphedema Network.

Vitamin D and Breast Cancer

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Dr. Pam Goodwin, oncologist at Mt. Sinai Hospital in Toronto, CA  presented Thursday afternoon on breast cancer and vitamin D, a very hot topic.

There’s lots of interest in this connection because there are studies showing an association between vitamin D blood levels and breast cancer risk:  Lower levels show increased risk.

However, Dr. Goodwin pointed out that this association is only observed when blood was drawn after diagnosis.  When data was analyzed looking at blood drawn before diagnosis, there was no association.  She reported that the strongest studies do not show an association vitamin D and breast cancer risk.

What about for survivors?

For women with diagnosed breast cancer, many studies show low levels of vitamin D status at diagnosis.  However, two very recent studies show vitamin D deficiency to be more uncommon, though  present in 10-20% of these women.  This may be because more women are taking vitamin D supplements.

Some data show an association between vitamin D deficiency and shorter survival, but a randomized clinica trial did not show any association.

With all these conflicting results, what is the take-away message?

Dr. Goodwin’s take:

  1.  The evidence thus far is not convincing that there is a causal association between vitamin D status and breast cancer risk or for prognosis.
  2. Regardless of the vitamin D and breast cancer association, there are other health problems associated with D deficiency, so it is reasonable to use vitamin D supplementation to obtain sufficient blood levels.
  3. It will also be important to study, using preclinical studies, what the effects are of higher levels (above sufficient levels) of nutrients, such as vitamin D. 

 

Finally, Dr. Goodwin advises breast cancer patients on chemotherapy to use the standard dose of vitamin D supplement until we know more about chemotherapy and vitamin D.