Two characteristics of cancer cells are lack of differentiation (specialization) and rapid growth or proliferation. Many malignant tumors have been found to contain vitamin D receptors (VDR), including breast, lung, skin (melanoma), colon, and bone. Biologically active forms of vitamin D, such as 1,25(OH)2D and its analogs, have been found to induce cell differentiation and/or inhibit proliferation of a number of cancerous and noncancerous cell types maintained in cell culture. Results of some, but not all, human epidemiological studies suggest that vitamin D may protect against various cancers. However, it is important to note that epidemiological studies cannot prove such associations.
Previously it was thought that the active form of vitamin D - calcitriol, which is a potent anti-cancer agent, was only made in the kidney. The researchers think having a local cancer-fighting 'factory' is part of the breast's natural immune response to a tumour. Laboratory studies have also shown that vitamin D stops cancer cells from dividing and that it enhances cell death. And the epidemiological evidence points to a link between rates of, and deaths from, breast cancer and exposure to sunlight.
Dietary calcium and vitamin D were found to lower breast cancer risk in a cancer prevention study reported by researchers from the American Cancer Society (ACS). ACS nutritional epidemiologist Marji McCullough, ScD, RD, who reported the findings, tells WebMD that more study is needed to understand how vitamin D and calcium influence breast cancer risk. "The evidence of a modest protective benefit [for dietary vitamin D and calcium] is fairly consistent, but we still don't know if premenopausal and postmenopausal women benefit equally," she says after a study found similar.
Vitamin D is found in many dietary sources such as fish, eggs, fortified milk, and cod liver oil. The sun also contributes significantly to the daily production of vitamin D, and as little as 10 minutes of exposure is thought to be enough to prevent deficiencies. This is the reason why the vitamin is also called the “sunshine vitamin.” Women who get lots of vitamin D are less likely to develop breast cancer, suggests a pair of studies that add to the already strong evidence that the “sunshine vitamin” helps prevent many types of cancer.
Presenting one study at a meeting of the American Association for Cancer Research found that high levels of vitamin D translated to a 50 percent lower risk of breast cancer. Even modestly higher levels resulted in 10 percent less risk, which would translate to 20,000 fewer cases a year if it were true of all American women.
It's always possible that the cancer reduces vitamin levels, rather than lower vitamin levels promoting cancer. But taken with the earlier studies, the circumstantial case for maintaining vitamin D to stave off, and now to slow the progress of beast cancer, is even stronger.
Vitamin D is a steroid hormone precursor that has recently been found to play a role in a wide variety of diseases. Current research indicates vitamin D deficiency plays a role in causing seventeen varieties of cancer as well as heart disease, stroke, hypertension, autoimmune diseases, diabetes, depression, chronic pain, osteoarthritis, osteoporosis, muscle weakness, muscle wasting, birth defects and periodontal disease.
A new study made by researchers from Toronto comes to support the idea that vitamin D is essential to our health, especially women’s health. According to their findings, breast cancer patients with low levels of vitamin D are nearly twice as likely to have the disease spread to other parts of their bodies and are 73 percent more likely to die from it.
The findings are the first to link lack of vitamin D to the progression of breast cancer and the fate of those with the disease.
The study, sponsored by the Breast Cancer Research Foundation, especially involved Canadian women because the country’s weak winter sunlight is not strong enough for nearly half the year to create the nutrient the natural way, through the action of strong ultraviolet light on skin. In fact, vast amount of evidence indicates that people living in the northern regions of the globe have higher cancer rates than those living closer to the equator, possibly because of less sunshine and vitamin D.
The study followed 512 women diagnosed with breast cancer at the University of Toronto hospitals between 1989 and 1995. Only one in four women in the study had sufficient blood levels of D at the time they were first diagnosed with breast cancer. Those who were deficient were nearly twice as likely to have their cancer recur or spread over the next 10 years, and 73 percent more likely to die of the disease.
“These are pretty big differences. It’s the first time that vitamin D has been linked to breast cancer progression,” said study leader Dr. Pamela Goodwin of Mount Sinai Hospital in Toronto, as quoted by the Associated Press.
There is insufficient research to show that vitamin D supplements can help women already diagnosed with breast cancer or that supplements can prevent cancer, Dr. Goodwin said. She also warned women not to take excessive amounts of vitamin D because high amounts of vitamin D are also not good for the organism, leading to increased cancer risk.
What Dr. Goodwin recommends is women get tested for vitamin D deficiency and to correct low levels with the help of a physician.
The findings of the study are the more worrisome as more and more dermatologists urge people to stay away from the sunlight or to use sunscreen as a way to lower risks of skin cancer. However good this advice is, it has its negative side too, as staying away from the sunlight leads to lower vitamin D levels, studies show.
Although death rates from breast cancer have been declining, possibly due to earlier detection and diagnosis, on a national level, breast cancer still represents the second leading cause of cancer death for women after lung cancer. According to the American Cancer Society, more than 180,000 American women are diagnosed with breast cancer every year, and almost 41,000 will die because of it. In Canada, breast cancer is expected to strike about 22,400 women this year and an estimated 5,300 will die from it.
The study, released by the American Society for Clinical Oncology on Thursday, will be presented in Chicago at the society’s annual meeting later this month.
SOURCES:
Pamela Goodwin, M.D., medical oncologist, Mount Sinai Hospital, University of Toronto; May 6 teleconference with Nancy E. Davidson, M.D., director, breast cancer program, Johns Hopkins Kimmel Cancer Center, Baltimore, and president, American Society of Clinical Oncology
http://lpi.oregonstate.edu
http://www.reuters.com
http://ap.google.com
http://www.webmd.com
http://news.bbc.co.uk
http://www.bmj.com/
http://www.iom.edu.
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