Sweat-gland cancer rare, hard to diagnose

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Most skin conditions are irritating and ugly rather than dangerous, and are curable with timely treatment. But not cancer of the sweat gland. Though it remains a rare disease, its incidence is on the upswing, US research reveals.

According to a study by the American Institute for Cancer Research, the rate of sweat gland cancers increased 170 percent between 1987 and 2005 to 5.1 cases per 1 million people annually

The research also found that men are more prone to the disease than women. Non-Hispanic whites face a higher risk at 5.7 per million while the rates for African Americans and Asian Pacific Islanders are 3.5 and 2.5.

The ratio also increases with age and is 100 times more likely for people aged 80 and above than for people between 20 and 29.

But since cancers rarely develop in skin-related parts such as sweat gland, hair follicles, and sebaceous glands, they pose a diagnostic challenge.

Sweat gland cancer was first described by American doctor Joseph Leonard Goldstein and his team in 1982. Again because of its rarity, its study has been limited.

In Vietnam, between 2002 and 2007 the HCMC Oncology Hospital diagnosed only four cases, and none since then.

Contributing factors

The causes of sweat gland cancer remain unclear to researchers even today. They speculate UV ray exposure and immunity suppression through the use of arthritis medications and anti-inflammatory drugs for a long time could be contributing factors.

UV radiation may well play an important role in causing the cancer, which would explain why the incidence is lower in people with dark skin.

The malignancy is dispersed, researchers have found, with cancer in the face accounting for 48.6 percent of the cases, scalp for 19 percent, torso for 17.4 percent, and neck and head for 14 percent. As reliable results cannot be obtained from clinical skin tests, a biopsy is needed.

In all four cases in Vietnam there was a hard tumor on the patient's skin, either on the legs, thighs, or shoulders. They all began as a small, hard lump without clear boundaries, affecting an area of the skin and making it darker or pinkish. Then it gradually grew and intruded into the tissues and bones, and caused sharp pain.

Another concern is that this cancer spreads quickly to lymph nodes, which are distributed along the body, including in the armpits and stomach. Thus, apart from the initial tumor, it also spreads to the armpits and neck. Diagnosis in this case requires doctors to use photographic tools such as ultrasound and X-ray of lungs to find cancer-spread infections in patients' liver, lungs or bones as cancer cells usually spread into these positions. Another approach is fine-needle aspiration biopsy of tissues from a tumor or metastasized cyst, which provides more exact results.

Since sweat-gland cancer is not very responsive to chemical treatment, surgery is considered a more effective option, especially if it is localized and has not spread to other parts.

Patients need an operation to remove the original tumors and clear cancerous ganglions. Post-operative scars should also be excised. The removal of cancerous ganglions is necessary in case of a recurrence of tumors or the patient has poor cellular differentiation type, according to histology results.

Sweat-gland cancers progress through rapid destruction of the cell structure, and their recurrence rate at the operated area is 47-59 percent.

Thus patients require close post-operative monitoring to discover recurrence and the appearance of other types of skin cancer.

Factors which help to project the disease are also difficult to identify. Currently, doctors can only check on few related factors such as the size of tumor, histology type, and whether the cancer has spread into the lymph nodes or has metastasized in other parts of the body.

Overall a five-year survival rate is 99 percent if the disease is localized and only 43 percent when the cancer has spread to other parts of the body.

RARE DISEASE, BUT PRECAUTIONS NEEDED

Sweat-gland cancers occur in the skin's sub-structures, appearing initially as small dots and developing gradually over a long time before suddenly growing into large tumors.

There is no pathognomonic image that enables exact diagnosis as the symptoms are only clear when the lumps on the skin start to bleed or emit fluids. Therefore, when there is a small lump or unusual change in our skin, we should get it checked immediately.

Preventing this cancer also requires a healthy lifestyle, regular exercise, and limited consumption of alcohol. Try not to be exposed to the sun between 10 a.m. and 3 p.m., wear masks and long, bright colored clothes when going out to avoid exposure to UV rays. Consume plenty of vegetables to get enough vitamins and water.

By Dr. Bui Chi Viet

Original Vietnamese article has been published on Saigon Tiep Thi

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