Skin cancer fear 'may harm bones'
Worries over skin cancer mean that some people are shunning the sun altogether - which could endanger their health, a poll has found.
The National Osteoporosis Society (NOS) says lack of vitamin D - part-made by being in the sun - could raise the chances of brittle bone disease.
It advised having lunch outside, gardening or hanging out the washing.
A Cancer Research UK spokesman agreed, but said enough vitamin D could be made long before the first signs of sunburn.
Skin cancer rates have soared in recent years, and health campaigners increasingly urge people to limit the amount of time they spend in direct sunlight without the protection of sunscreen or clothing.
However, the NOS said its survey of more than 2,600 people in June revealed that many believe there is no such thing as safe sun exposure.
Three-quarters of those questioned said that sunscreen should always be applied before going out in the sun.
However, the NOS said that not getting at least 15 to 20 minutes of sunlight on the skin every day could be harmful.
Light falling on the skin produces vitamin D, which is important for bone strength, and studies suggest that low levels of this could raise the risk of osteoporosis, which affects half of all women and a fifth of men over the age of 50.
Professor Roger Francis, from the NOS Medical Board, said its finding showed the success of public health messages on skin cancer.
"We are not advocating spending lengthy periods in the sun, as too much sun causes skin ageing and melanoma.
"Furthermore, staying in the sun too long means that the body breaks down surplus vitamin D shortly after it is produced.
"Lying on the beach for two weeks will not top up levels for the rest of the year."
He urged people to get out into the light every day - even during cloudy days - to get enough vitamin D to last through the winter.
Simply sitting by a closed window or in a conservatory was not enough, he said, as this did not produce vitamin D.
Caroline Cerny, from Cancer Research UK, which runs its SunSmart campaign to warn people about skin cancer, said the key was a sensible approach.
"The amount of time in the sun required to make enough vitamin D changes from person to person and depends on things like skin type, time of day, time of year, and where you are in the world .
"We all need a bit of sunshine in our lives, but it's important to remember that the amount of sun needed to make enough vitamin D is always less than the amounts that cause reddening of the skin or sunburn."
Skin Cancer, malignancy in the skin, and the most common of all cancers. There are three main types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and melanoma. Basal cell carcinoma, the most common type, develops in the basal, or bottom, layer of the epidermis, the top layer of skin. Squamous cell carcinoma, the second most common type, develops in the upper layers of the epidermis. The American Cancer Society estimates that basal cell and squamous cell skin cancers account for more than 1.3 million new cases each year, but for only 1,900 deaths. In Canada, 68,000 new cases of basal cell and squamous cell skin cancer is diagnosed each year.
The third type of skin cancer is melanoma. It develops in the melanocytes, or pigment cells, which are found throughout the basal layer. Melanoma is the most dangerous type of skin cancer and is responsible for about three-quarters of all skin cancer deaths. About 48,000 new cases of melanoma are diagnosed annually in the United States, and an estimated 7,700 people die from this disease each year. The incidence of melanoma has been increasing faster in the United States than any other form of cancer, and a person born in the early 1990s is 12 times more likely to develop melanoma than a person born in the early 1940s. In Canada, about 3,100 new cases of melanoma are diagnosed each year.
SYMPTOMS AND DIAGNOSIS
Early detection and treatment are the keys to survival, especially for melanoma. Any of several skin changes may signal skin cancer and should be reported to a physician. These include any change in the size, shape, color, or texture of a mole or other darkly pigmented area; any mole that begins to itch or becomes tender; the development of a new mole or other growth, particularly if it feels hard; any mole or other growth that spontaneously or persistently bleeds; a skin ulcer that does not heal; and a black spot under a toenail or fingernail that extends beneath the cuticle. To confirm a diagnosis a physician may perform a biopsy, removing a small piece of the skin to examine under a microscope for the presence of cancerous cells.
Skin cancers can grow in any part of the skin, but approximately 90 percent develop in areas exposed to the sun, especially the face, neck, backs of the hands, and the scalps of bald men. Exposure to direct sunlight, especially during childhood, is the chief risk factor for skin cancer, and the greater the number of blistering sunburns a person has had, the greater the risk of developing skin cancer later in life. People with pale skin are at greatest risk for skin cancer, particularly if their skin burns or freckles easily.
A family history of skin cancer can also increase a personís risk. Studies are in progress to determine which individuals are genetically predisposed to the disease. In 1996, for example, scientists reported the discovery of a gene they believe causes basal cell carcinoma. The gene, called patched or PTC, helps control cell growth and development. If the gene is missing, defective, or damaged by ultraviolet radiation, unrestrained cell proliferation may result. Another aberrant gene, called multiple tumor suppressor (MTS1), has also been linked to melanoma.
Diet may also play a role. A recent study found that patients on a diet of 20 percent fat had fewer precancerous growths and non-melanoma skin cancers than those who ate a normal diet of about 38 percent fat.
Sunlight that reaches the earthís surface contains two kinds of ultraviolet (UV) radiation. UV-A and UV-B both contribute to sunburn and skin cancer, as well as to conditions such as premature wrinkling of the skin. The U.S. Environmental Protection Agency has determined that depletion of the ozone layer in the upper atmosphere will continue to increase radiation damage to skin and skin cancer rates in the future.
The Skin Cancer Foundation recommends that people avoid the sun at its peak (from 10 am to 4 pm), seek shade, and cover up with clothing and a brimmed hat. It also recommends the regular use of sunscreen, which has been shown to prevent the development of precancerous keratoses (skin lesions that appear during middle age) and decrease the risk of skin cancer. Because skin cancer develops slowly over many years, it is important that protection from too much sun begin in childhood. Indoor tanning parlors should also be avoided, since they expose people to the same kinds of ultraviolet radiation as sunlight. Learning to identify early signs of skin cancer is crucial, as is periodic self-examination of the skin. Any skin changes or abnormalities should be reported to a physician.
Although skin cancer is the most common cancer in the United States, it is also the most curable, especially when detected early. One of several surgical methods is used to remove the cancerous tissue. In some cases, the tissue is destroyed through the application of intense cold (cryosurgery). In advanced cases, surgical removal of the tissue coupled with radiation, chemotherapy, or both may be required.
A class of vitamin-based drugs called retinoids have been shown to reduce the number of basal cell and squamous cell carcinomas. However, the drugs can cause liver abnormalities, bone problems, fetal malformation, and other undesirable side effects.
Potential skin cancer treatment studies now underway include the use of the drugs interleukin-2 and interferon. A vaccine to reduce the recurrence of melanoma has shown promise in early tests.
The five-year survival rate for patients with malignant melanoma is 88 percent. For melanoma that has not spread to other parts of the body, the five-year survival rate rises to 95 percent. About 82 percent of melanomas are diagnosed at this stage. The five-year survival rate lowers to 58 percent for melanoma that has spread to adjacent organs. If the disease has spread to distant parts of the body, the five-year survival rate drops to 13 percent.