Women with breast cancer have an increased risk of breast cancer recurrence. To reduce recurrence risk, patients receive adjuvant therapy -- treatments given after primary therapy to improve the chance of long-term survival. One side effect of adjuvant therapy is osteoporosis -- weakening or thinning of bones. Adequate intake of vitamin D, along with calcium, reduces the risk of adjuvant therapy-induced bone loss and fractures. Ongoing studies are examining additional uses of vitamin D in reducing the risk of breast cancer.
Risk Factors
The risk of breast cancer recurrence is highest if a woman is younger than 40 when she is first diagnosed, and in the first three to five years after treatment and decreases over time. Women with larger tumors, especially those larger than 5 cm , and lymph node involvement have an increased recurrence risk.
Tumors where the cells bear little or resemblance to normal breast cells signal an increased recurrence risk as do instances where the breast cells contain proteins, called hormone receptors, that bind the hormones estrogen and progesterone.
Treatments
Local recurrence may be treated surgically, by removal of the complete breast or removal of new lumps and radiation therapy. In addition, local and regional recurrences are treated by adjuvant therapy, such as chemotherapy, hormonal therapy or a combination.
Drugs such as tamoxifen and raloxifene block the growth-promoting effects of estrogen on breast cells. Aromatase inhibitors reduce estrogen in the body by inhibiting the action of a protein that converts some other hormones into estrogen. Adjuvant chemotherapy drugs, such as docetaxel and methotrexate, kill quickly growing cells, such as cancer cells.
Vitamin D Effects
Studies on lab-grown cells and animal models of human tumors show that Vitamin D can inhibit cancer cell growth and tumor angiogenesis --formation of blood vessels, promote cell differentiation -- process by which cells acquire specialized functions -- and promote apoptosis -- a kind of cell death. These properties encourage further investigation of a role for vitamin D in cancer prevention and treatment
Vitamin D in Adjuvant Therapy
Osteoporosis is one of the long-term complications of successful tumor treatment using chemotherapy and hormonal therapy. Adequate intake of vitamin D and calcium can reduce the risk of osteoporosis-induced bone loss and fractures. Doctors may also prescribe other drugs to treat osteoporosis in breast cancer patients. Consult your doctor before choosing a vitamin D regimen specific to your health concerns.
Other Potential Uses
An analytical study conducted by scientists from Denmark in 2008 indicated a trend of lower breast cancer risks in women with the highest vitamin D intake --in this case, greater than ten micrograms per day-- when compared with women with the lowest vitamin D intake.
Clinical studies are also under way to test whether vitamin D can reduce the risk of breast cancer in both healthy and high-risk women. A clinical trial led by doctors from King Faisal Specialist Hospital in Saudi Arabia is investigating the effect of a high dose of vitamin D2, given along with a chemotherapy drug, in affecting the progression of disease and survival of patients with metastatic breast cancer -- advanced cancer that has invaded other parts of the body. Wake Forest University scientists are investigating the utility of paricalcitol, an analog of an active form of vitamin D, in improving the efficacy of chemotherapy drugs in treatment of metastatic breast cancer. Data from such clinical studies is going to determine whether vitamin D and its analogs can reduce the risk of breast cancer recurrence.
References
- The GAEA initiative: Breast Cancer Recurrence Background Information
- National Cancer Institute: Vitamin D and Cancer Prevention: Strengths and Limits of the Evidence
- MayoClinic.com: Vitamin D
- US National Institute of Health Registry of Clinical Trials
- National Cancer Institute: Adjuvant and Neoadjuvant Therapy for Breast Cancer
