Breast Cancer News (8/18): Survival and Vitamin D, Exercise and CYP2D6 Variations

Recent studies suggest a worse prognosis for breast cancer patients with low blood levels of vitamin D. Do vitamin D supplements improve prognosis? A recent review asked that very question. Today, we'll also share the latest research on how CYP2D6 variations and exercise affect survival. As always, links to the studies below may be found on the treatment pages of the LATESTBreastCancer.com website.

Vitamin D supplementation for cancer patients

Should breast cancer patients take vitamin D supplements to improve prognosis? An August 11 review in The Oncologist evaluated 25 studies involving several cancers. For breast cancer, the two studies reviewed reached opposite conclusions about the prognostic importance of vitamin D. Three prostate cancer trials showed no survival benefit of vitamin D supplementation. The authors concluded that even though low vitamin D was associated with worse prognosis in some cancers, the "currently available evidence is insufficient to recommend vitD supplementation in cancer patients in clinical practice."

Does this mean that breast cancer patients should not take vitamin D? Not necessarily.

First, The Oncologist study reviewed only two breast cancer studies. Recent studies suggest that low serum vitamin D at diagnosis may be associated with a worse prognosis. An April 29 University of Rochester Medical Center study (under the News tab) linked low vitamin D with more aggressive tumors and a worse prognosis. A July 27 Breast Cancer Research study found that low serum vitamin D "may be associated with poorer overall survival and distant disease-free survival in postmenopausal breast cancer patients." These recent studies were likely not considered in The Oncologist review. (The Breast Cancer Research study also noted that the only two previous studies were inconclusive.)

Also, even though vitamin D supplementation is not yet proven to improve prognosis, recent studies suggest it may be beneficial for breast cancer patients to preserve bone mineral density (Annals of Oncology, April 2 and Breast Cancer Research and Treatment, March 8) and to reduce bone and joint pain associated with aromatase inhibitors (Breast Cancer Research and Treatment, June 21).

The bottom line is that breast cancer patients with low serum vitamin D should discuss vitamin D supplementation with their doctors.

CYP2D6 variations do not affect risk of recurrence

Variations in CYP2D6 genes affect how tamoxifen is metabolized. Some women metabolize tamoxifen well. Some do not. Do variations in CYP2D6 affect the risk of recurrence? According to a August 5 study in Cancer, no. Researchers from MD Anderson found that variations in CYP2D6 genes "had no significant effect" on the risk of recurrence in women with early breast cancer treated with adjuvant tamoxifen.

Exercise after breast cancer diagnosis may improve survival

Studies have associated exercise with improved quality of life, but can exercise affect breast cancer survival? An August 12 study in Breast Cancer Research and Treatment revealed that exercise after a breast cancer diagnosis may affect the regulation of tumor suppressor genes, which have "favorable impacts on survival outcomes of breast cancer patients."

Please check back tomorrow for more breast cancer research news from LATESTBreastCancer.com.