Basal cell carcinoma

Basal cell carcinoma (BCC) is a type of skin cancer that usually develops in the areas most exposed to the sun, being the most frequent neoplasm. It starts in the basal cells, which are responsible for the renewal of skin cells. It usually appears in the form of a lump and occurs most frequently in sun-exposed areas such as the head and neck.

Most basal cell carcinomas are due to prolonged exposure to ultraviolet (UV) radiation from sunlight. This can cause mutations in the DNA of these cells that make them cancerous.

Basal cell carcinomas have an important hereditary component so that people with a family history or who have already suffered from this type of cancer are more predisposed to develop it.

Among the non-genetic risk factors that may contribute to its development are:

  • Exposure to UV radiation. Most basal cell carcinomas are caused by prolonged exposure to ultraviolet light from the sun, tanning lamps and commercial tanning beds. Severe sunburns also increase your risk.
  • Use of this methodology to treat other conditions may predispose the area to this type of cancer.
  • Fair skin. The risk is higher among people who have fair skin, freckles or who burn easily.
  • Most develop in people over the age of 45 because basal cell carcinoma sometimes takes decades to develop.
  • Immunosuppressive drugs.
  • Exposure to arsenic.
  • Hereditary syndromes such as xeroderma pigmentosum or Gorlin-Goltz syndrome.

Although UV radiation is the main risk factor, there is a genetic basis for BCC based on reduced protection against mutagenesis and reduced DNA damage repair. In an association study of over 30,000 cases and some 65,000 controls, 68 significant loci were identified. Many of these overlapped with loci associated with other skin cancers such as keratinocytic cancer. Among the loci identified, common variants of the BRCA2 and CTLA4 gene, the target of immunotherapy in melanoma, stood out.

Symptoms

It usually manifests itself on the parts of the body most exposed to the sun, especially on the face and neck. It appears as a skin lesion that usually has some of these characteristics:

  • Skin-colored, shiny-appearing bump.
  • Brown, black or bluish lesion.
  • A flat, scaly patch.
  • A whitish, waxy, scar-like lesion without defined borders.

Prevention

The most important causative factor is UV radiation which is absorbed by skin cells causing DNA mutations.

To reduce the risk of basal cell carcinoma, the following measures are recommended:

  • Reduce exposure to sunlight, especially in the middle of the day. Always use sunscreen, long-sleeved clothing, long pants and hats. Ultraviolet light is more intense at higher altitudes and special care should also be taken when practicing winter sports such as skiing.
  • Avoid self-tanning cameras.
  • High-risk persons should self-examine once a month. In addition, it is advisable for them to visit a dermatologist regularly for examinations in order to detect precancerous lesions at an early stage.

Number of observed variants

13.5 million variants

Number of risk loci analyzed in the study

68 loci

Bibliography

Liyanage UE, Law MH, Han X, et al. Combined analysis of keratinocyte cancers identifies novel genome-wide loci. Human Molecular Genetics. 2019 Sep;28(18):3148-3160.

American Cancer Society [March 2022]

Mayo Clinic [March 2022]

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