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Basal Cell Carcinoma

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Apr.26.2023

Basal Cell Carcinoma

Synopsis

Key Points

  • Basal cell carcinoma is an extremely common malignancy of the epidermis that usually occurs on the head or neck and rarely metastasizes
  • Most common basal cell carcinoma subtype is nodular basal cell carcinoma, which generally appears as a pearly white, dome-shaped papule with notable telangiectatic surface vessels
  • Excisional biopsy with histopathology is gold standard for diagnosis; include deep reticular dermis if lesion is suspected to be more than a superficial process r1
  • Surgical excision is gold standard for treatment
  • Radiation therapy is a good alternative for patients who are not surgical candidates or who refuse surgery r1
  • Topical medications such as 5-fluorouracil or imiquimod may be used for superficial basal cell carcinoma in patients who are unable or unwilling to undergo surgery or radiation therapy r1
  • Systemic medications such as hedgehog pathway inhibitors (vismodegib and sonidegib) and immunotherapy (cemiplimab) may be used in advanced disease
  • Complications may include destruction of adjacent tissue in cases of advanced, aggressive disease and rarely metastasis
  • 100% survival with nonmetastatic, noninvasive basal cell carcinoma r2
  • Continued long-term surveillance is essential; 30% to 50% of patients will develop another basal cell carcinoma within 5 years r1

Urgent Action

  • In immunosuppressed patients, early skin biopsy (as soon as skin lesion is noticed) and treatment of premalignant and malignant lesions are paramount r3

Pitfalls

  • A conservative approach to treatment based on the knowledge that basal cell carcinoma is rarely fatal can put patient at risk of serious morbidity (eg, destruction of adjacent tissue in cases of advanced, aggressive basal cell carcinoma)
  • May be difficult to diagnose basal cell carcinoma in skin of color owing to pigmentation and rarity r4

Terminology

Clinical Clarification

  • Basal cell carcinoma is an extremely common malignancy of the epidermis that usually occurs on the head or neck and rarely metastasizes

Classification

  • Clinical and histological subtypes r5
    • Nodular
      • Most common subtype, representing 50% to 80% of lesions
      • Primarily involves head and neck
      • Generally appears as a pearly white, dome-shaped papule with notable telangiectatic surface vessels and rolled borders r6r7
      • Sometimes pigmented with melanin
    • Superficial
      • Second most common subtype; 10% to 30% of lesions
      • Appears as well-defined erythematous scaly plaque with central clearing
      • Sometimes pigmented with melanin
      • Most common on trunk
    • Infundibulocystic
      • Well-defined pearly papule
      • Commonly on head and neck in older adults
    • Fibroepithelial (fibroepithelioma of Pinkus)
      • Uncommon
      • Indolent form
      • Often on trunk
    • Morpheaform
      • Less than 10% of lesions
      • Infiltrated plaque with slightly shiny surface and ill-defined borders; may resemble a scar
      • Commonly on head or neck
      • Tends to be more aggressive and has higher rate of recurrence
    • Infiltrative
      • Poorly defined, indurated or indented plaque; white, yellow, or pink color
      • May have overlying crusts, erosion, or ulceration
    • Micronodular
      • May be erythematous macules or thin papules or plaques
      • Micronodular changes may be present alongside other histological subtypes
    • Basosquamous
      • Rare: less than 2% of cases
      • Well-defined nodular or superficial squamous cell carcinoma—appearance with underlying histological features of both basal cell and squamous cell carcinomas
      • Mostly found on head and neck
      • Aggressive and associated with high rates of recurrence and metastasis
  • Risk stratification (risk of recurrence)
    • Formal staging with TNM system and American Joint Committee on Cancer stage grouping is not used; instead, stratified by risk of recurrence per National Comprehensive Cancer Network guidelines r8
      • Low-risk basal cell carcinoma r1
        • Area less than 20 mm on trunk and extremities (excluding pretibia)
        • Well-defined borders
        • Primary
        • No immunosuppression
        • Not at site of prior radiation therapy
        • Pathology
          • Nodular, superficial, and other nonaggressive subtypes
          • No perineural involvement
      • High-risk basal cell carcinoma r1
        • Area 20 mm or larger on trunk and extremities (excluding pretibia)
        • Lesion of any size on head, neck, pretibia, hands, feet, and anogenital region
        • Poorly defined borders
        • Recurrent
        • Patient immunosuppressed
        • Lesion at site of prior radiation therapy
        • Pathology
          • Aggressive growth pattern (infiltrative, micronodular, basosquamous, morpheaform, sclerosing, or carcinosarcomatous features)
          • Perineural involvement

Diagnosis

Clinical Presentation

History

  • Skin lesion presenting with any of the following characteristics: r9r10c1
    • Nonhealing within 4 weeks c2
    • Dimpled at midpoint c3
    • Occurs on sun-exposed skin c4
    • Slowly enlarging c5
    • Bleeds occasionally or only when poked or knocked c6c7
    • Pruritic c8
  • May be asymptomatic r5c9
  • History of risk factors may include the following:
    • Previous basal cell carcinoma or other nonmelanomatous skin cancer
    • Family history of basal cell carcinoma c10
    • Chronic sun exposure, especially during childhood and young adulthood c11
    • Use of tanning booths c12

Physical examination

  • Typical lesions resemble a papule or nodule and may have the following characteristics: c13c14
    • Central ulceration, erosion, or depression c15c16c17
    • Waxy appearance c18
    • Raised or crusty border c19c20
    • Tendency to bleed when knocked or pulled c21
    • Translucent or pearly color c22c23
    • Pigmentation c24
  • Commonly occur in head and neck area, and within treatment field of prior radiation therapy; some subtypes occur on trunk or legs r1

Causes and Risk Factors

Causes

  • Arise in sun-damaged skin because of mutagenic effects of UV light on keratinocyte progenitor cells r5
  • Solar UV radiation is the main risk factor r11r12r13c25c26
    • UV-B (290-320 nm) rays are more powerful than UV-A in causing basal cell carcinoma c27
    • UV-A (320-400 nm) rays are less powerful than UV-B in causing basal cell carcinoma, but exposure to UV-A rays is usually much greater because UV-A is more prevalent than UV-B at the Earth's surface and many sunscreens do not block UV-A as well as they block UV-B c28
    • Effect is exacerbated by skin phenotype: fair skin, red or blond hair, light eye color, tendency to freckle, and inability to tan r5

Risk factors and/or associations

Age
  • Average age at diagnosis is 60 years; risk increases with advancing age r14c29
Sex
  • More frequent in males than females r15c30c31
Genetics
  • Certain genetic conditions increase susceptibility to UV-induced mutagenesis and are associated with elevated risk of basal cell carcinoma c32
    • Basal cell nevus syndrome (Gorlin-Goltz syndrome or basal cell carcinoma syndrome) r5r16r17c33
      • PTCH1, PTCH2, or SUFU
      • Autosomal dominant inheritance
    • Xeroderma pigmentosum r18c34c35
      • XPA through XPG and XPV
      • Autosomal recessive inheritance
    • Bazex-Dupré-Christol syndrome r5c36
      • Unknown gene
      • X-linked dominant inheritance
    • Rombo syndrome r5c37
      • Unknown gene
      • Autosomal dominant inheritance
    • Rothmund-Thomson syndrome r5c38
      • RECQL4 and USB1
      • Autosomal recessive inheritance
    • Werner syndrome r5c39
      • WRN/RECQL2
      • Autosomal recessive inheritance c40
    • Bloom syndrome r5c41
      • BLM/RECQL3
      • Autosomal recessive inheritance
    • Muir-Torre syndrome r5c42
      • MLH1, MSH2, MSH6, or PMS2
      • Autosomal dominant inheritance
Ethnicity/race
  • More common in people with fair skin, red or blond hair, and light eye color r1c43c44c45c46
  • In the US, lifetime risk of developing basal cell carcinoma is 30% or greater in White people r19c47
  • Also occurs in people of color; most common form of skin cancer in Asian and Hispanic people, second most common in Black people (may be pigmented and often misdiagnosed) r4r20c48c49c50
Other risk factors/associations
  • Albinism r2c51
  • High exposure to sunlight, especially during childhood and young adulthood r2r15r21c52c53c54
  • Geography of patient residence, especially during childhood: r21
    • Lower latitudes, high altitude, southern hemisphere c61c62c63
  • Non-UV radiation to the skin
    • Ionizing: generally, this refers to x-ray therapy for acne (used before approximately 1950) c64c65
    • Nonionizing
      • Psoralen and UV-A therapy for psoriasis c66
  • Arsenic exposure c67
  • Immunosuppression
    • HIV infection, immunosuppressive drugs c68c69
    • Smokingr23r24, especially in femalesr23c70c71
    • Solid organ transplantr27, especially heart and kidney r25r26c72
      • Over half of solid organ transplant recipients will develop nonmelanoma skin cancer, usually basal cell carcinoma or squamous cell carcinoma r28
  • Alcohol use may increase risk of aggressive histologic subtypes (eg, morpheaform, infiltrative, micronodular) r29c73

Diagnostic Procedures

Primary diagnostic tools

  • Initial workup includes history, physical examination including complete skin examination, and biopsy of suspicious lesion r1c74c75
    • Evaluation of suspected basal cell carcinoma with dermoscopy can help rule out other conditions in the differential diagnosis and assist in diagnosis r30c76
      • Dermoscopy may allow diagnosis of shallow, nodular basal cell carcinoma; however, not a substitute for definitive biopsy c77
      • Refer patients to a dermatologist for dermoscopy, unless the primary care physician has received dermoscopy training relevant to basal cell carcinoma r31
    • Optical coherence tomography and reflectance confocal microscopy may aid in diagnosis, particularly in conjunction with dermoscopy r16r32c78c79
    • Skin biopsy with histopathologic analysis of tissue sample confirms diagnosis c80c81
      • Include deep reticular dermis in biopsy if lesion is suspected to be more than a superficial process r1
      • In immunosuppressed patients, early skin biopsy (as soon as skin lesion is noticed) and treatment of premalignant and malignant lesions are paramount
  • 3-Dimensional imaging studies are recommended if there is suspicion for extensive disease (eg, invasion of deep soft tissue or bone, perineural disease) r1
    • MRI with contrast enhancement is preferred for evaluation of perineural invasion or periorbital spread r16c82
    • CT with contrast enhancement is preferred if bone involvement is suspected c83
  • Consider genetic testing to exclude genetic syndrome in patients who develop basal cell carcinoma before age 20 years r16c84

Imaging

  • MRI or CT r1c85c86
    • Perform when extensive disease such as bone involvement, perineural invasion, or deep soft tissue involvement is suspected
    • MRI preferred over CT for suspected perineural disease

Procedures

Dermoscopy c87
General explanation
  • Noninvasive optical procedure for evaluation and differentiation of skin lesions
  • Generally provides enough information to determine histopathologic subtype and tumor extension of a basal cell carcinoma r33
  • Refer patients to a dermatologist for dermoscopy, unless the primary care physician has received dermoscopy training relevant to basal cell carcinoma r31
Indication
  • Skin lesion with clinical suspicion of malignancy; applicable for shallow, nodular basal cell carcinoma
  • May help rule out other conditions in the differential diagnosis and assist in diagnosis; however, not a substitute for definitive biopsy
Skin biopsy c88
General explanation
  • Selection of biopsy technique
    • Factors to consider include tumor morphology, expected histologic subtype, expected depth, and anatomic location, as well as patient-specific factors such as bleeding diatheses and abnormal wound healing
      • Obtain more extensive biopsy tissue (eg, excisional biopsy, multiple scouting biopsies) if tumor appears to be deeply invasive or has other aggressive features
      • Perineural invasion may not be identified with incomplete biopsy
    • Excisional biopsy with histopathology is gold standard for diagnosis
    • Shave biopsy (removing only epidermis and outer dermis with a tangential technique) is most commonly done and adequate for superficial basal cell carcinoma
    • Punch biopsy (removing all layers of skin into subcutaneous fat with a small tool resembling a cookie cutter) provides a thicker specimen
  • Terminology: distinguish excisional biopsy from an excision with margins; the latter is performed as treatment to completely remove the tumor
Indication
  • All suspected basal cell carcinoma cases
Interpretation of results
  • Documents histopathologic subtype and presence of features that increase risk of local recurrence (eg, perineural invasion, invasion beyond reticular dermis) r1c89c90c91c92
    • Low-risk subtypes
      • Nodular
      • Superficial
      • Infundibulocystic
      • Fibroepithelial
    • High-risk subtypes
      • Morpheaform
      • Infiltrative
      • Micronodular
      • Basosquamous
      • Sclerosing
      • Carcinosarcomatous

Differential Diagnosis

Most common

  • Seborrheic keratosis c93
    • Macules/papules made by epidermal cell proliferation
    • Shave biopsy identifies epithelial proliferation with horn cysts and no sign of malignancy
  • Keratoacanthoma c94
    • Low-grade skin tumor that resembles squamous cell carcinoma and rarely metastasizes
    • Excisional biopsy results show well-differentiated squamous epithelium with a central mass of keratin
      • Deep incisional biopsy may be adequate
      • Shave biopsy is not enough to distinguish histology from that of basal cell carcinoma
  • Actinic keratosis c95
    • Scaly, rough skin lesions (usually smaller than 1 cm) that typically begin as small macules
    • In basal layer of skin, biopsy shows abnormal keratinocytes varying in shape and size with atypical nuclei
  • Squamous cell carcinoma c96d1
    • Malignant proliferation of epidermal keratinocytes that occurs most commonly on chronically sun-exposed skin in older patients
    • Presents as more invasive lesion than basal cell carcinoma
      • Even early (in situ) squamous cell carcinoma shows full-thickness epidermal involvement with atypical keratinocytes
      • Dermal invasion is common
    • Biopsy covering full thickness of skin shows cancerous squamous cells
      • Shave biopsy is not sufficient for diagnosis

Treatment

Goals

  • Complete removal of tumor with clear histologic margins and minimal functional and cosmetic compromise
  • In settings of metastatic basal cell carcinoma (very rare): remission with extension of survival time

Disposition

Recommendations for specialist referral

  • Referral to a dermatologist for confirmation of diagnosis and appropriate treatment
  • Histopathologic analysis is often done by a dermatopathologist
  • Plastic/cosmetic/reconstructive surgeon to do excision or excisional biopsy involving cosmetically challenging sites or reconstruction after excision
    • Refer patients requiring Mohs surgery to a surgeon specifically trained in this technique
  • Multidisciplinary tumor board consultation, including a radiation oncologist and medical oncologist, is recommended in situations where either radiation therapy, chemotherapy, or both are under consideration

Treatment Options

Surgical excision is first line treatment of all types of basal cell carcinoma r9

  • If required, reconstruction after surgical resection can be performed immediately or delayed for days to weeks, depending on type of repair, patient characteristics, and logistics r34
    • Immediate reconstruction is preferred in patients with basal cell carcinoma with high-risk factors if clinical margins are well defined under bright lighting and magnification or dermoscopy r35
    • Delayed reconstruction, or Mohs micrographic surgery, is first line approach for patients when lesion is in a high-risk anatomic area and has poorly defined margins under bright lighting and magnification or dermoscopy r35

Local low-risk basal cell carcinoma r1

  • Standard excision with 4-mm clinical margins and with closure techniques such as linear closure, second intention healing, or skin graft
    • If margins are positive after excision, recommend 1 of the following:
      • Mohs micrographic surgery or other forms of peripheral and deep en face margin assessment
      • Standard reexcision for trunk and extremities (excluding pretibia, hands, feet, nail units, ankles)
      • Radiation therapy for nonsurgical candidates
  • Destructive techniques are an alternative when there is low risk of local extension or recurrence; disadvantage is that these do not allow histologic examination of tissue r9
    • Electrodesiccation and curettage may be performed in areas without hair growth (ie, not scalp, pubic and axillary regions, or beard area in males), provided that treatment be changed to excision if tumor appears to extend beyond the dermis r1
    • Radiation therapy for nonsurgical candidates or those with advanced age and poor performance status
      • Usually reserved for patients aged 60 years or older r1
    • Laser ablation may be used for low-risk disease in patients unable or unwilling to undergo surgery or other therapies r9r36
    • Topical medications (5-fluorouracil or imiquimod), cryotherapy, or photodynamic therapy may be used for superficial basal cell carcinoma in patients who are unable or unwilling to undergo surgery or radiation therapy r1r35r37
      • Cure rates are at least 10% lower than surgical approaches r1
      • Imiquimod has greatest efficacy over a 5-year follow-up, while cosmetic results are best with photodynamic therapy r38r39
      • Cryosurgery resulted in a clearance rate of 100% at 1 year in one randomized trial of treatment of nonfacial, superficial basal cell carcinoma (228 tumors in 97 patients); however, wound healing times are longer compared to curettage, and cosmetic result may be poorr19r40

Local high-risk basal cell carcinoma r1

  • Mohs micrographic surgery or other forms of peripheral and deep en face margin assessment
    • Mohs is the most reliable strategy with lowest recurrence rate:r320% to 2.5% r41
    • If margins are positive after excision:
      • Multidisciplinary tumor board consultation to discuss options
        • Repeat resection
        • Radiation therapy
        • Systemic therapy (vismodegib or sonidegib) if curative radiation therapy or surgery not feasible
    • If margins are negative after excision:
      • If extensive perineural or large-nerve involvement, consider adjuvant radiation therapy
  • Standard excision, using wider margins with linear or delayed repair
    • If margins are positive after excision:
      • Recommend Mohs micrographic surgery or resection with complete margin assessment
        • If residual disease is present, consider multidisciplinary tumor board consultation regarding options (radiation therapy or systemic therapy)
    • If margins are negative after excision:
      • If extensive perineural or large-nerve involvement, consider adjuvant radiation therapy
  • Radiation therapy for nonsurgical candidates r1
  • Systemic therapy (vismodegib or sonidegib) if neither radiation therapy nor surgery is feasible r1
    • Vismodegib may also have a role as neoadjuvant therapy to reduce tumor burden before surgical excision of locally advanced tumors in functionally sensitive locations r42

Nodal or distant metastatic disease r1

  • Multidisciplinary tumor board consultation to discuss options
    • Surgery
    • Systemic therapy with hedgehog pathway inhibitor (vismodegib or sonidegib) r43
      • Anti-PD1 antibody cemiplimab-rwlc may be used to treat patients with metastatic or locally advanced basal cell carcinoma who have previously been treated with a hedgehog pathway inhibitor or for whom a hedgehog pathway inhibitor is not appropriate r1r36r43
    • Treatment in a clinical trial
    • Radiation therapy

Drug therapy

  • Topical therapies
    • Appropriate in cases of superficial basal cell carcinoma in patients who are unable or unwilling to undergo surgery or radiation therapy r1
      • 5-Fluorouracil c97
      • Imiquimod c98
  • Intralesional chemotherapies r32
    • Interferon alfa-2b c99
    • 5-Fluorouracil c100
    • Bleomycin c101
  • Systemic agents
    • Indicated with advanced or metastatic disease r1r37r43
      • Hedgehog pathway inhibitors
      • PD-1 inhibitor
        • Cemiplimab-rwlc c104
  • Drug Therapy: Basal Cell CarcinomaEfudex (fluorouracil) package insert. Bridgewater, NJ: Bausch Health US, LLC; 2021 Oct. Erbitux (cetuximab) package insert. Indianapolis, IN: Eli Lilly and Company; 2022 Feb. Odomzo (sonidegib) package insert. Cranbury, NJ: Sun Pharmaceutical Industries, Ltd.; 2019 May. Erivedge (vismodegib) package insert. South San Francisco, CA: Genentech, Inc: 2023 Mar. Aldara (imiquimod) package insert. Bridgewater, NJ: Valeant Pharmaceuticals International, Inc; 2018 Apr. Libtayo (cemiplimab) package insert. Tarrytown, NY: Regeneron Pharmaceuticals, Inc.; 2022 Nov.
    MedicationCommon regimensLife-threatening or dose-limiting adverse reactionsNotable or nonemergent adverse reactionsSpecial considerations
    Antimetabolite - nucleoside metabolic inhibitor
    Fluorouracil (topical)
    Fluorouracil (topical) monotherapy

    Photosensitivity

    Allergic contact dermatitis
    • Skin burning
    • Crusting
    • Leukocytosis
    • Pruritus
    • Rash
    • Scarring
    • Soreness
    • Ulceration

    Increased risk of serious or fatal adverse reactions in patients with low or
    absent dihydropyrimidine dehydrogenase activity
    Epidermal growth factor receptor (EGFR) antagonist
    Cetuximab
    Cetuximab monotherapy

    Cardiopulmonary arrest
    • Dermatologic toxicity
    • Infusion-related reactions
    • Interstitial lung disease (ILD)
    • Radiation recall

    Diarrhea
    • Electrolyte abnormalities
    • Headache
    • Infection

    Effective contraception required during and after therapy for 2 months for
    females of reproductive potential
    Hedgehog pathway inhibitor
    Sonidegib
    Sonidegib monotherapy

    Increased creatine phosphokinase (CPK)
    • Muscle cramps
    • Musculoskeletal pain
    • Premature epiphyseal fusion
    • Myalgia

    Abdominal pain
    • Alopecia
    • Anorexia
    • Diarrhea
    • Dysgeusia
    • Fatigue
    • Headache
    • Nausea/vomiting
    • Pain
    • Pruritus
    • Weight loss

    Advise patients not to donate blood or blood products during treatment and for at least 20 months after the last dose
    • Advise males not to donate semen during and after therapy for at least 8
    months after the last dose
    • Effective contraception required during and after therapy for at least 20
    months for females of reproductive potential and for at least 8 months for
    males with female partners of reproductive potential
    Vismodegib
    Vismodegib monotherapy

    Arthralgia
    • Dermatologic toxicity
    • Muscle spasms
    • Increased creatine phosphokinase (CPK)
    • Premature epiphyseal fusion

    Ageusia
    • Alopecia
    • Anorexia
    • Constipation
    • Diarrhea
    • Dysgeusia
    • Fatigue
    • Nausea/vomiting
    • Weight loss
    • Advise patients not to donate blood or blood products during treatment and for at least 24 months after the last dose
    • Advise males not to donate semen during and after therapy for 3 months
    after the last dose
    • Effective contraception required during and after therapy for 24 months
    for females of reproductive potential and for 3 months for males with female
    partners of reproductive potential
    Immune response modifier
    Imiquimod
    Imiquimod monotherapy
    • Skin
    weeping/erosion
    • Photosensitivity
    • Flu-like symptoms
    • Edema
    • Erythema
    • Excoriation
    • Flaking/scaling/dryness
    • Induration
    • Pruritus
    • Scabbing/crusting
    • Skin burning
    • Ulceration
    Programmed death receptor-1 (PD-1) blocking antibody
    Cemiplimab
    Cemiplimab monotherapy
    • Adrenal insufficiency
    • Colitis
    • Diabetic ketoacidosis
    • Exfoliative dermatitis
    • Hepatitis
    • Hyperthyroidism
    • Hypophysitis
    • Hypothyroidism
    • Infusion-related reactions
    • Myocarditis
    • Nephritis
    • Neurotoxicity
    • Pneumonitis
    • Thyroiditis
    • Diarrhea
    • Fatigue
    • Musculoskeletal pain
    • Rash
    • Effective contraception required during and after therapy for at least 4
    months for females of reproductive potential

Nondrug and supportive care

Procedures
Excisional surgery c105
General explanation
  • Tumor is excised with surrounding normal tissue margins
  • Followed by any of the skin reconstruction techniques: linear closure, secondary intention healing, or skin graft
Indication
  • Low-risk basal cell carcinoma if lesion can be excised with 4-mm clinical margins r1
  • High-risk basal cell carcinoma, using wider margins r1
Mohs surgery c106
General explanation
  • During a single procedure under local anesthesia, tumor is removed in multiple stages; patient remains on site between stages
  • Excision margin is inspected repeatedly so that additional excision can be done as necessary to attain negative margins
Indication
  • High-risk basal cell carcinoma r1
  • Basal cell carcinoma with aggressive histology
  • Basal cell carcinoma at anatomic location requiring tissue conservation (eg, eyelid) r1
  • Low-risk basal cell carcinoma, if margins are positive after excision r1
Contraindications
  • Procedure may be too long and tedious for patient to tolerate
  • Patient does not tolerate repeated injections of local anesthetic
  • Very large or unresectable tumor
Electrodesiccation and curettage c107c108
General explanation
  • Procedure in which tumor is scraped away down to the dermal layer with a curette, followed by denaturation of area by electrodesiccation r1
  • Up to 3 cycles of the procedure are completed in 1 session r1
Indication
  • Low-risk basal cell carcinoma r1
  • Superficial, noninfiltrative lesion r1
Contraindications
  • Areas of terminal hair growth such as scalp, pubic and axillary regions, and beard area in males r1
  • Tumor reaching subcutaneous adipose layer r1
Cryosurgery c109
General explanation
  • Lesion is destroyed with very cold temperature using a cryoprobe (instrument with tip cooled by liquid nitrogen) r1
Indication
  • Superficial, noninfiltrative lesion r1
  • May be used for superficial basal cell carcinoma in patients who are unable or unwilling to undergo surgery or radiation therapy r1
Laser ablative therapy c110
General explanation
  • Basal cell carcinoma is burned off with a laser
Indication
  • Small, superficial basal cell carcinoma
Radiation therapy r44c111
General explanation
  • Tumor is destroyed using high-energy radiation (electron beam, high energy photons, or proton beam) or orthovoltage radiation
  • Isotope-based brachytherapyr45 may be useful for sites on head and neck r1
Indication
  • Patients aged 60 years or older with low-risk and high-risk basal cell carcinomas of nodular or infiltrative subtypes and who: r35
    • Have a tumor that is inoperable because of size or location r1r44
    • Are not eligible for or decline surgery, or express preference for radiation therapy r44
    • Have a tumor for which incomplete surgical excision and reexcision are not possible r44
Contraindications
  • Genetic diseases that predispose patient to increased radiation sensitivity r44
    • Nevoid basal cell carcinoma syndrome (Gorlin-Goltz syndrome)
    • Xeroderma pigmentosum
    • Basal cell nevus syndrome
    • Bazex syndrome
    • Epidermodysplasia verruciformis
  • Recurrent basal cell carcinoma after previous radiation therapy r35
  • Lesion is in area of poor blood supply (eg, lower limbs) r35
  • Patients younger than 60 years in whom late effects of radiation therapy could be problematic r35
  • Lesion is invading bone or cartilage r35
Photodynamic therapy c112
General explanation
  • Photosensitizers are delivered topically to lesions in prodrug form (eg, aminolevulinic acid)
  • Prodrug is metabolized in situ and generates a photoactive substance
  • A light source applied to this area energizes the photosensitizer, which generates highly reactive singlet oxygen locally resulting in necrosis, apoptosis, and possibly increased local immune effects
Indication
  • May be used for superficial basal cell carcinoma in patients who are unable or unwilling to undergo surgery or radiation therapy r1
Contraindications
  • Skin sensitivity to light at 400 to 450 nm
  • Porphyria
  • Porphyrin allergy

Comorbidities c113

Special populations

  • Patients with diabetes may present late with basal cell carcinoma, particularly when it occurs on lower extremities
    • Increases the need for excisional surgery and Mohs surgery, because the basal cell carcinoma tends to be deeper

Monitoring

  • Continued long-term surveillance is essential; 30% to 50% will develop another basal cell carcinoma within 5 years r1
  • During first 5 years, examine patient at least every 6 to 12 months; then at least annually for life r1c114

Complications and Prognosis

Complications

  • Destruction of adjacent tissue in cases of advanced, aggressive basal cell carcinoma c115
  • Recurrence at original tumor site c116
  • Metastatic basal cell carcinoma (very rare) r46c117

Prognosis

  • Overall prognosis is excellent, as most cases are curable when detected and treated early
  • 100% survival with nonmetastatic, noninvasive basal cell carcinoma r2
  • 5-year survival rate is only 10% in cases of recurrent and invasive basal cell carcinomas, because these do not respond well to chemotherapy r47
  • Median overall survival for metastatic basal cell carcinoma ranges from 8 months to 7.3 years r4
  • Recurrence rate is low
    • 5% recurrence rate within 5 years after standard surgical excision r6
    • 1% recurrence rate after Mohs surgery r6
  • Risk of recurrence is directly related to the adequacy of excision; 1% of recurrence rate for lesions excised with clear margins compared with 31% to 41% recurrence rate when margins are positive r48
    • Overall, approximately 11% of cases are incompletely excised
  • 30% to 50% of patients will develop another basal cell carcinoma within 5 years r1
  • Patients are also at increased risk of developing other forms of skin cancer r36

Screening and Prevention

Screening

At-risk populations

  • Anyone with elevated levels of sun exposure (eg, occupational or recreational exposures) c118c119

Screening tests

  • US Preventive Services Task Force concluded that evidence is insufficient to assess the balance of benefits and harms of visual skin examination by a clinician to screen for skin cancer in adults r49
  • Skin Cancer Foundation recommends the following: r50
    • Self-examination of skin from head to toe every month c120
    • Formal skin examination each year by a dermatologist if earlier history of basal cell carcinoma c121

Prevention

  • General skin cancer prevention
    • US Preventive Services Task Force recommendations are as follows: r51
      • Counsel young adults, adolescents, children, and parents of young children about minimizing exposure to UV radiation for persons aged 6 months to 24 years with fair skin types to reduce their risk of skin cancer
      • Selectively offer counseling to adults older than 24 years with fair skin types about minimizing their exposure to UV radiation to reduce skin cancer risk
      • Evidence indicates that the net benefit of counseling all adults older than 24 years is small
      • In determining whether counseling is appropriate in individual cases, patients and clinicians should consider the presence of risk factors for skin cancer
      • Methods of minimizing UV light exposure include the following:
        • Avoid midday sun c122
        • Avoid sunburns c123
        • Cover up; wear a broad-brimmed hat and sun-protective clothing c124
        • Wear sunscreen of at least sun protection factor 15 c125
          • Benefit is most evident and clear regarding prevention of squamous cell carcinoma, but less so regarding basal cell carcinoma r12
          • Benefit/risk of sunscreen and sun protection factor level in preventing basal cell carcinoma is controversial r12r52
          • Not a substitute for use of hats and sun-protective clothing
        • Wear sunglasses c126
        • Do not use tanning beds or sunlamp c127
  • Nicotinamide has been shown to decrease the incidence of nonmelanoma skin cancers, including basal cell carcinomas r1
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