Foot skin cancer most common in Singapore
One of the most common areas for skin cancer, melanoma to appear in Singapore is on the soles of the feet, according to the National Cancer Centre.
Melanoma is the most deadly form of skin cancer. The disease affects one in 200,000 Singaporeans by the age of 55. Prolonged sun exposure is the main cause of melanoma.
Early stages of melanoma could look like a mole on the sole of the feet, or a foot ulcer that won’t heal. Other common sites of melanoma in Singaporeans are on the palms and under the nails of fingers and toes (acral lentiginous melanoma,) according to NCC. They are not areas of the body that you would normally expect skin cancer to surface.
It is one of the least known fact about melanoma in Singapore. In general, Asians are more susceptible to foot and hand melanoma than any other ethnic groups. Studies in Japan, Hong Kong and among Asian Americans also showed high incidence of acral lentiginous melanoma. ALM can also appear on the eyes and eye-lids, and in the body’s mucous system like the digestive tract.
By contrast, the location of melanoma is different in Caucasians. The lesion typically shows up on the arms, chest and legs (superficial spreading melanoma.) Melanoma affects more Caucasians than Asians, but because of the unusual location of the melanoma in Asians, and the mis-conception that Asians don’t get skin cancer, the tumours on the feet and hands are often over-looked. Delays in seeking treatment sharply decreases the survival rate from melanoma in Asians. Foot melanoma is also a particularly aggressive form of melanoma, which is also why prognosis is poor.
In the US, the reported five-year survival rate for patients with primary ALM — where the disease has not spread to other parts of the body — was at 80.3%, compared to 91.3% for all types of melanoma. The gap increases in the 10th year, where the survival rate for ALM patients was at 67.5% versus 87.5% for all types of melanoma. Early treatment is particularly crucial for improving the survival rate of ALM patients, according to the study.
Skin cancer is the 6th most common cancer among men, and the 7th most common among women in Singapore, according to the National Cancer Centre. There are 1,719 reported cases of skin cancer in Singaporean men yearly between 2010-2014, compared to 1,381 cases in Singaporean women. The risk of skin cancer increases with age, and recipients of solid organ transplant also have a higher rate of skin cancer.
There are three types of skin cancer: basal, squamous and melanoma. Basal and squamous skin cancer are more common, and are curable if treated early. Melanoma is the least common but the most dangerous because of the ability to metastasis early to spread to other parts of the body.
Melanoma is an abnormal growth in the melanocytes cells, the deep layer of the skin epidermis. Melanocytes produces the skin pigment, melanin. The risk of melanoma increases with prolonged or intensive exposure to the sun’s UV-A and -B radiation.
The Health Science Authority in October 2015 approved a new drug, Keytruda for use in advanced melanoma. The drug is a type of immunotherapy to help patients fight cancer cells by boosting the body’s immune system. It’s an alternative to chemotherapy, where both good and bad cells are destroyed. Immunotherapy is less invasive and clinical trials show promising results.
Skin damage from the sun’s UV radiation is cumulative. It doesn’t happen overnight, but over a period of time. The median age of a melanoma patient in Singapore is 55 years old. It is one reason why sun protection should start early in life. It could be we are prone to foot melanoma because of our penchant for flip flops and sandals. We generally wear less covered footwear.
Trauma and Chemicals, Risk Factors
There are also studies which have suggested other risk factors for foot and hand melanoma. Previous trauma on the feet or hands like a burn, cut or an injury increases the risk of melanoma. Another risk factor is heavy exposure to agricultural chemicals. In a study conducted in Taiwan, researches found some of the melanoma patients were farmers, and have worked outdoors without any protection on the feet or hands. The hands and feet were subjected to trauma, and were exposed to agricultural chemicals. Researches said the trauma and chemicals may have contributed to the melanoma in the farmers.
Prevention is the best medicine for foot and hand melanoma:
5 Tips to Keep Hands & Feet Safe
- Inspect areas of the feet regularly —including soles, underneath toenails (particularly the big toe nail) and between toes — for moles or ulceration. If you have recently suffered an injury or a cut on the foot or palm, check for any bruise that won’t fade or ulceration that won’t heal.
- If you wear nail polish, remove it occasionally to check the skin underneath the nails. Melanoma could appear as a discolouration under the nails.
- Wear water shoes on the beach, and covered footwear and socks when outdoors instead of flip flops. If you have children, choose covered footwear for them. Prolonged sun exposure is harmful in any age but more so for children.
- Apply sunscreen, which offers both UV-A and -B protection, on areas of the feet and hands not protected by clothing or shoes. Don’t forget to apply sunscreen on the soles as well as the top of the feet, and on the hands.
- Wear protective gloves and rubber boots when handling pesticides or other agricultural chemicals.
Jie Ying, Foo (2015, December 17). Mole turns out to be cancerous. The New Paper, pp. 9.
Skin Cancer, National Cancer Centre Singapore.
Belle, Susan; Del Rooso, James; Kim, Grace. Skin Cancer in Asians. Journal Clinic Aesthetic Dermatol. v.2(10); 2009 Oct. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2923934/
Malignant Melanoma of the Foot – Foot Health Facts, American College of Foot and Ankle Surgeons.