This has been a tough week for breast cancer survivors. On the medical front, the benefits of taking extra vitamin D has come under question and the ability of the bone-strengthening drug Zometa to prevent a cancer recurrence may not be as great as we thought. On the personal front, the death of Elizabeth Edwards was a true, heartfelt blow to all cancer survivors and most people. Still, there are messages of hope in all of these events.
Vitamin D is an essential vitamin for strong bones. Adequate levels in the body are needed to prevent thin bones and osteoporosis. It is unique among vitamins in that the human body can make it upon exposure of the skin to sunlight. Beyond these established facts, however, lies a large body of suggestive medical studies that link the vitamin to the prevention of cancer and health of the immune system. In the past few years, a medical bandwagon has arisen that doctors and patients have jumped onto. Many patients have vitamin D levels checked by their doctors and many are told they are deficient. Many more individuals who are not deficient believe that extra vitamin D can improve their health, even prevent cancer, and take thousands of units of extra vitamin D daily.
But how much proof is there that extra vitamin D can prevent cancer? What levels in the blood define vitamin deficiency? Can a person take too much vitamin D and do themselves harm? These questions were the topic of an important new report from the Institute of Medicine, entitled "Dietary Reference Intakes for Calcium and Vitamin D." The researchers who wrote this report reviewed all of the available evidence about calcium and vitamin D and answered the questions posed above. I obtained a copy of this report and reviewed its 300+ pages. It should give us all pause. Essentially, the committee concluded:
- There is not solid evidence demonstrating that taking extra vitamin D can prevent cancer.
- Doctors and laboratories are over-estimating deficiency by setting normal levels too high; deficiency should be defined as serum 25OHD (25 hydroxyvitamin D) levels less than 30 nmol/L (12 ng/mL).
- The recommended dietary allowance (RDA) of vitamin D for adults is 600 IU; the maximum amount is 4,000 IU daily.
- Too much vitamin D can be harmful.
I recommend that everyone check out the weblink above and read more about the recommended intake of calcium and vitamin D. Future studies may be able prove a stronger link between supplemental vitamin D and the prevention of cancer; in the mean time, don't overdo it.
Zoledronic Acid to Prevent a Cancer Recurrence
In 2009, a study of 1803 premenopausal women with early stage breast cancer who were treated with endocrine therapy (such as Tamoxifen) after surgery were randomized to receive (or not receive) infusions of the bone-strengthening drug zoledronic acid (Zometa). Zometa is commonly used to treat patients whose cancer has already spread to the bones. The aim of the study was to determine if the drug could prevent a cancer relapse if used early in the course of the disease. Indeed, Zometa did show a statistically significant (3.2% absolue, 36% relative) reduction in the cancer relapse rate. But this was just one study. Still, there was great enthusiasm for it and many oncologists awaited confirmatory studies. Unfortunately, a study just presented and reported on in The New York Times did not support the above study. At this time, the role of zoledronic acid in the prevention of breast cancer remains unproven; most oncologists will likely reserve its use for postmenopausal women. Further studies underway will clarify the best way to use Zometa and a newer bone-strengthening drug called denosumab.
Regarding Elizabeth Edwards, I can only extend my sincere condolences to her family and many friends. She was an extraordinary, highly gifted woman who faced incredible challenges in her life with which we can all empathize. As the son of a single mother who raised three children on her own, I am sensitive to the struggles of such women. I listened to the audio version of her book Resilience, in which her poignant, searching voice brought the listener just a little closer to the tragic events in her life, such as the loss of her son and private/public betrayal by her husband. Cancer, in comparison, seemed to be something she was just going to deal with. She did so with incredible dignity and resilience. Cancer survivors can honor her memory by trying to do the same, as hard as that may be at times. Appreciate each day of life, it is the greatest gift.