Melanoma is not the only tumor that can affect the skin. This is because the different types of cancer can originate from the various cells that make up the epidermis. Melanoma develops from melanocytes, the cells of the epidermis, which are responsible for producing melanin, the substance, which gives the skin its natural color and protects it from sunlight. The most common skin tumors are, however, basal cell carcinoma and squamous cell carcinoma with a more frequent incidence in men and older age. We talk about this topic with Dr. Riccardo Borroni, Humanitas dermatologist.
Basal cell Carcinoma
Basal cell carcinomas originate from the cells of the deepest layer of the epidermis, the basal layer. For this reason, too, they are often colloquially referred to as “basaliomes”. They are by far the most frequent tumors and usually occur after the age of 50, although they are increasingly common in younger subjects. These cancers are very often formed on the skin of the face, particularly on the nose, but also on the scalp, neck and back of the hands. They are in fact the parts of the body most exposed to the action of sunlight. Nevertheless, basal cell carcinoma can form on any part of the body, even on the legs or torso.
Like melanoma, there are various risk factors for basal cell carcinoma: phenotypic ones, with bright skinned, eyed and haired individuals at greater risk; environmental risk factors, with prolonged sun exposure over the years and particularly without protection against ultraviolet radiation of the sun rays. Ultraviolet radiation from lamps and sunbeds is also harmful for the skin. The DNA of the basal cells is damaged by UV rays, triggering the onset of the carcinoma. For this reason, having developed a basal cell carcinoma represents a warning sign for the development of another basalioma over the course of life. The genetic predisposition to basal cell carcinoma is very rare, which occurs with Gorlin-Golz’s syndrome, characterized not only by the appearance of basal cell carcinomas in young adulthood (20-25 years), but also by skeletal malformations, cerebral tumors and typical depression points in the palm of the hands and feet.
Basal cell carcinoma has a very slow development and hardly spreads to other organs. Its prognosis is favorable, and the treatment of first choice of basal cell carcinoma is surgical, and very often a solution. In selected situations, when the tumor is superficial and located in “noble” sites such as the face or in cases where the person’s condition (including age and some pharmacological therapies) contributes to an increased risk of complications of surgery (hemorrhage, infections), other therapeutic options can be considered.
More specifically, for superficial basal cell carcinomas, imiquimod 5% can be indicated, which applied in the form of cream on the basalioma, activates the immune system to eradicate sick cells. Alternative treatment can also include photodynamic therapy: a drug (aminolevulinate) is applied that makes cells sensitive to light, which also activates the drug, “destroying” the cancer cells of the skin. In rare forms of metastatic basal cell carcinoma, or when the size and anatomical location of the tumor does not allow radical surgical removal, systemic therapy with vismodegib may be used.
Squamous cell Carcinoma
This cancer also originates, like basal cell carcinoma, from keratinocytes, the most represented type of cell in the epidermis. These may undergo a neoplastic transformation resulting in squamous cell cancer. Squamous cell carcinoma has a more aggressive clinical course than basal cell carcinoma and, although in rare cases, it may give lead to metastases.
Like basal cell carcinoma, this form of skin cancer develops on the skin regions most exposed to sunlight. However, since the causes of squamous cell carcinoma do not only include ultraviolet radiation, this tumor may even form in the mouth or lips.
The risk factors are always related to light phenotype (blonde or red hair, light skin, blue or green eyes); exposure to ultraviolet radiation, the use of lamps and sun beds. The immune system plays an important role in the risk of onset and progression of squamous cell carcinoma, which is the most frequent tumor in transplanted subjects taking immunosuppressive therapies. Infection with Human Papilloma virus (HPV) can be a risk element for the onset of squamous cell carcinoma in the genitals and mouth.
The first choice treatment of squamous cell carcinoma is surgical. For squamous cell carcinoma in situ, which is not yet invasive (“Bowen’s disease”) photodynamic therapy is useful.
Actinic keratosis
The diagnosis of actinic (or solar) keratosis is relevant for squamous cell carcinoma. This is a precancerous lesion related to UV exposure damage. Without treatment, over time, some actinic keratosis may in fact evolve into squamous cell carcinoma. The lesions commonly occur on the scalp of bald men, but also on the face and back of the hands. The keratosis presents as small pink or red spots, which tend to join together, with a rough surface, which evoke a punctuating sensation to touch. Solar keratosis can even appear on the lips, especially the lower lip because it is more exposed to the sun’s rays, which in this case takes the name of actinic cheilitis.
The treatment of actinic keratoses, due to their superficial nature, almost never involves the use of scalpel. For isolated lesions cryotherapy and diathermic coagulation are useful, while in cases where the lesions are extended or converging, in addition to the previously mentioned photodynamic therapy, diclofenac 3%, imiquimod 3.75% and mebutated ingenol are indicated, three different drugs with their own mechanism are applied locally and act on the “cancer field”.
Similar to melanoma, is it useful to inspect the moles for both of these cancers? “Not exactly. Most actinic keratosis, squamous cell and basal cell carcinomas are not pigmented and therefore epidermal carcinomas generally do not have the appearance of a mole”, says Dr. Borroni. The entire surface of the skin – he continues – must be carefully inspected, looking for stains or pink nodules or desquamant lesions, or even small scabs, with which these tumors may occur. The use of the dermatoscope is always useful, as it can highlight specific microscopic characteristics, not visible to the naked eye, which allow confirming the diagnosis and making the subsequent therapeutic path of the patient more efficient “.
These are the signs and lesions to pay attention to: “A small crust, which seems healing but tends to appear repeatedly in the same position, is a clue that should bring the patient to the attention of the dermatologist. Even a nodular lesion, especially if associated with bleeding or if it develops rapidly in recent weeks or months, is a sign that should not be underestimated,” concludes the specialist.
