Metal implant allergy could result in skin cancer

A new study provides the first mechanistic insight into the tumor-promoting role of chronic allergic contact dermatitis in skin cancer development.

“Our study directly relates to skin cancer development in the context of allergy to metal implants, a previously unrecognized adverse event. However, there are well established associations between allergy to metal dental restorations and tattoo dyes and the increased risk of skin cancer,” lead author and dermatologist Shadmehr Demehri, M.D., Ph.D., tells Dermatology Times.

Dr. Demehri, instructor of medicine, Washington University in St. Louis, and colleagues learned about a patient whose fractured ankle was repaired with a metal rod. The patient developed a skin rash near the implant post-surgery and was found to be allergic to nickel in the implant. The rash persisted even after the implant was removed. Years later, the patient developed Marjolin’s ulcer at the surgical site.

The researchers conducted a mouse study of contact allergy, which found chronic skin inflammation caused by continuous skin contact with allergens contributes to tumor development.

“This model supported cancer development so strongly that some mice developed invasive squamous cell skin cancers similar to the patient’s tumor,” Dr. Demehri says.

When placed near the skin, fewer than 5 percent of patients develop an inflammatory rash related to metal implants, according to the study.

“As doctors that diagnose and treat allergic contact dermatitis, dermatologists play a critical role in both determination of allergy to metals in patients prior to receiving a metal implant and diagnosing the rash and treatment of it early after the implant is placed. These approaches will prevent chronic dermatitis and the more serious consequences of it in patients,” Dr. Demehri says.

Next: Testing findings in other settings

These most recent findings help to explain previously reported associations between some dental restoration materials and tattoo inks with cancers on the skin or in the mouth. Dr. Demehri says she and colleagues are testing their findings other settings.

For now, dermatologists and others should be aware and treat when needed.

“The rash that persists (a) few weeks after the allergenic material is removed from the skin should alert the physician to investigate whether the rash is a simple dermatitis or if there is another, more serious, pathology underlying the persistence of the skin rash. The precise diagnosis can be obtained with a skin biopsy and tissue culture to rule of any neoplastic or infectious etiology,” Dr. Demehri says. “Our data suggests that early treatment of allergic contact dermatitis by removal of the allergenic material and aggressive treatment of the rash will prevent the development of a chronic inflammatory environment that can promote skin cancer development.

“The early detection and treatment is key because, as seen in our patient, (a) few months of exposure to an allergenic metal can result in cancer development and its persistence even after the implant is removed,” she says.

The study was published online Oct. 8 in the Journal of Clinical Investigation.

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