Actinic keratoses: What are the risks if left untreated?

Key Points

Amsterdam - Most dermatologists are taught that actinic keratoses (AKs) should be treated as soon as possible, due to the risk of these lesions developing into a squamous cell carcinoma (SCC).

According to one dermatologist, though, calling an actinic keratosis a cancer is just a matter of standpoint.

"From a pathogenic point of view, AK is already the stage 0 or the in situ phase of SCC. However, from the public health point of view, one cannot say that SCC is something which will kill the patient if it is not treated early, which is simply not the case with AK.

He says that from a pathogenic point of view, all in situ SCCs presenting as AKs probably won't turn into invasive carcinoma. Even if the physician delays and treats the patient when the tumor becomes more obvious, the risk of metastasis is low, unless it presents on the lips or the ears, or develops in immunosuppressed patients, such as in organ transplant recipients.

"As a political health issue, AK cannot be classified at the same level of priority as melanoma in situ. It is a cancer that will not threaten your life, unless it metastasizes in rare and neglected cases, which is very low.

"When you miss an early melanoma, your life is in danger, which is simply not the case when you miss an early AK," Dr. Grob tells Dermatology Times.

He says that physicians have many opportunities and a lot of time to detect SCC, and it is not mandatory to treat every single AK, at least from a life-saving point of view.

Implications of AKs

AK is a risk marker. Patients who present with AKs have a higher risk of developing other skin cancers such as basal cell carcinoma and malignant melanoma. The presentation of AKs is a reflection of the long-term sun exposure and sun damage that a patient has.

Secondly, having a number of actinic keratoses from a cosmetic point of view can be aesthetically unacceptable to the patient, as it is a manifestation of skin aging, such as wrinkles or lentigos.

Patients with AKs may simply want to have them removed for vanity's sake.

Treating AK can also serve to ultimately prevent its development into an invasive SCC.

"In this case, treating AK is much more interesting, and the issue is debatable. Most AKs will probably not develop into an invasive squamous cell carcinoma, and many aggressive SCCs arise de novo and do not develop from a pre-existing AK.

"Squamous cell carcinomas that develop from AKs are usually slow-growing tumors, giving the patient and the clinician a lot of time to react before they really become a danger to the patient.

"There are physicians that are of the conviction that AKs are cancers, and if they are not removed immediately, the patient will die. This is simply not the case, unless the lesions are on the mucous membrane, the ear or the patient is immunosuppressed or has a genetic fragility, such as xeroderma pigmentosum," Dr. Grob says.

"It is a good idea to treat AKs, but not a mistake to leave them be and perform routine skin exams," he says.

Lastly, physicians who do treat AKs should also treat the cancerization field. Dr. Grob says actinic keratosis is only the "visible" part of a tissue disease.

However, immediately next to this visible lesion, there are the same mutations within the skin. Therefore, the danger is not only the lesion that is visible, because in this site, the dysplasia impacts the keratinization process.

"If there is no impact of the dysplasia on the keratinic process, you do not see these lesions, but this does not mean that the skin surrounding AKs is normal and that there are no mutations occurring as a result of excessive sun damage," Dr. Grob says.

After the AK is treated, the physician should address the mutations in the surrounding skin.

"For the moment, treatments with imiquimod, Solaraze (diclofenac sodium, SkyePharma) or PDT have proven to help, but none have shown a curative effect on the cancerization field in a randomized control trial.

"Oral retinoids have some effect, but the risk/benefit ratio is very low. To receive the desired and required therapeutic effect, you have to take retinoids at high doses and for an extended period of time, which may prove dangerous to the patient," Dr. Grob says.