Updated:  Friday, October 27, 2006

Basal Cell and Squamous Cell Carcinoma  (Non-Melanoma Skin Cancer)

Overview

• The skin consists of two layers: outer epidermis and supporting dermis
• The skin can repair and renew itself
• Keeps moisture inside the body
• Millions of dead skin cells are lost each day
• The bottom layer of the epidermis is called the basal layer. It is just above the dermis.
• New cells are produced in the basal layer
• The dermis is made up of connective tissue, blood vessels, nerves
• The epidermis and the dermis contain hair follicles, sweat glands, sebaceous glands and nerve endings
• Skin is also the outermost limit of the immune system

General Information / Anatomy / Function / Statistics

• Skin cancers arise in outermost layer of skin
• Are usually on sun exposed skin
• Usually curable with early diagnosis
• Annual average increase
  • basal cell carcinoma is 3%
  • squamous cell carcinomas 3.5%
• Approximate number of new cases of non-melanoma skin cancers per year:
  • in Canada 66,000
  • in BC 13,000

Symptoms / Signs

• Diagnosis made on clinical examination
• People should be alert to any unusual skin condition such as a sore that does not heal, and have it checked by a family physician or a dermatologist

Etiology / Carcinogens / Risks

• Extent of sun exposure in childhood may be very important in the development of basal cell cancer, while more recent and chronic exposure for the development squamous cell carcinoma
• Prolonged skin contact with coal, tar, pitch, arsenic compounds, PUVA, or chronic ulcers may be associated with skin cancer development
• Men are affected two to three times as much as women
• Those most at risk:
  • All outdoor workers - farmers, fishermen, sailors
  • Fair-skinned people (especially redheads and blondes) because of their insufficiency of melanin (pigment substance that gives the skin its yellow-brown colour and filters out the ultraviolet rays of the sun)
  • Anyone repeatedly exposed to sun
• Except for those who tan easily, tanning should be vigorously discouraged especially in teenagers and young adults since it is exposure over time which is dangerous.  The sunburn today may be associated with skin cancer in 20 years.

Ozone Depletion and Skin Cancer

• The observed trend to increased incidence of melanoma and the common (non-melanomatous) skin cancers (basal and squamous cell carcinomas) during the past two decades is probably due to the popularization of sun bathing rather than depletion of the Earth's protective ozone layer by chlorofluorocarbons (CFC's)
• Although there has been an estimated 1-2% decrease in the global ozone concentration over the past twenty years, the effect on skin cancer rates has probably not yet been felt due to the time lag between cumulative and one-time exposure and cancer initiation. However, if ozone depletion continues at its present rate, by the year 2030, it is predicted that non-melonamatous skin cancer may increase by 12% and melanoma may continue to increase each year. However, if sun exposure behavior improves, then the predicted increase will be less.
• Ozone concentrations would be replenished but could take centuries if CFC's are banned totally throughout the world. To avoid the increase of CFC use, third world co-operation would be required.

Prevention

• Sunlight has several kinds of harmful rays, UVA, UVB, X-rays and cosmic rays. But the main effect at earth's surface is UVA and UVB. UVB rays cause sunburn skin cancer and photoaging of the skin (mottling, wrinkling). UVA is a cause of photoaging (sagging) and contributes to skin cancer risk.

Canadian Cancer Society Sunsense Guidelines

• Reduce exposure to the sun between 11 and 4
• SLIP on clothing to cover your arms and legs/trunk
• SLAP on a wide brimmed hat (brim of hat should be 3.0 inches or 7.5 cm)
• SLOP on broad spectrum sunscreen with SPF #15 or higher
• Avoid tanning parlours and sunlamps
• Keep babies under one year out of the sun
• Teach your children to Slip, Slap, Slop
• Use a "broad spectrum" sunscreen to absorb both UVB and UVA rays
• Such sunscreens are rated in strength
• Each strength is designated by a number (Sun Protection Factor or SPF)
• The higher the SPF, the greater the protection

Sunscreens

• The main objective of sunscreens is to prevent sunburn from UVB sunlight
• There is direct evidence available at present that sunscreens help to prevent squamous cell carcinoma skin cancer. There is insufficient evidence so far, indicating that sunscreens actually prevent basal cell or melanoma skin cancers.
• It is known, however, that sunburn occurring in childhood, adolescence, and post-adolescence contributes to a higher risk for basal cell cancer and melanoma 14 or more years later. This lag period may contribute to some confusion when studies are published which suggest that sunscreens do not protect against basal cell or melanoma skin cancers. Perhaps it is too early to show that sunscreens help to prevent basal cell or melanoma as the use of good sunscreens was not sufficiently prevalent until 10 years ago.
• There is no evidence that the active ingredients in sunscreens cause cancer in humans.
  Sunscreens are NOT intended to increase your exposure time but to increase your protection during unavoidable sun exposure
• SPF indicates protection from UVB rays primarily
• Protection from UVA is provided by the following chemicals:
  • PARSOL 1789 (AVOBENZANE)
  • DIBENZOYLMETHANES 
• Some of the sunscreens in Canada that have UVA protection (broad spectrum protection) are:
  • Ombrelle 30 to 60
  • UVGUARD 30
  • PRESUN ULTRA 30
• Complete physical block: zinc oxide, titanium dioxide
• Use a water-resistant sunscreen if possible
• Do not apply oils to the skin. They usually increase the likelihood of a burn
• FAIR-SKINNED people should use a sunscreen that has an SPF of AT LEAST 30
• Use lip sunscreen or zinc oxide. Lip sunscreens include commercial products as well as lipstick
• Use sunscreen liberally
• Sunscreens are effective immediately upon application
• Re-apply sunscreen after swimming or significant sweating
• Sunscreen ingredients are effective for at least two years (check expiration date on package)
• Opaque sunblocks such as zinc oxide or titanium dioxide should be used if maximal sun exposure is contemplated (e.g., skiers, mountain climbers)
• For further help contact your dermatologist or pharmacist

• Beware of cloudy days since the ultraviolet light that causes burns can penetrate light cloud cover, fog and haze. The amount of visible light is not a good guide to the amount of ultraviolet light
• Beware of reflective surfaces. Sand, snow and concrete can reflect up to 85% of the sun's damaging rays
• Protect children by keeping them out of the sun or minimizing sun exposure. Keep babies under one year old out of direct sunlight.
• Wear protective clothing if you do not wish to use a sunscreen on the body and arms (i.e., long sleeves). Wide-brimmed hats provide some protection but a sunscreen should be used as well.
  • U.S. Government FDA approved clothing made from sun-proof fabric is available for sale with an SPF factor of greater than 30
  • To date, there are no Canadian/USA standards for determining SPF factor for clothing
• Wear sunglasses with 100% UV protection; ultraviolet light can also cause cataracts
• Avoid tanning salons and sunlamps. The ultraviolet rays they emit can cause sunburn and premature aging of the skin and may increase the risk of skin cancer.
• Glass windows do filter the burning UVB rays, but do not filter UVA and do not prevent tanning.
• Key to saving lives from skin cancer: prevention, then early detection and prompt treatment

Diagnosis / Staging / Grading / Types

• Thorough physical examination
• Must be determined as benign pre-cancerous, or malignant by a physician
• The precise difference between "pre-cancerous and malignant" is often determined by biopsy (surgical removal of tissue sample)

Staging

• The BC Cancer Agency follows the American Joint Committee on Cancer (AJCC) Staging System for Non-Melanoma.
  
  Types

• There are two types of non-melanoma skin cancers.
  • Basal Cell Carcinoma (Basal Cell Epithelioma)
  • Squamous Cell Carcinoma

            Premalignant skin conditions to be watched

• Actinic Keratosis:
  • In sun exposed sites such as the forehead and back of hand
  • A thickening of the skin in a smaller area, often scaly, pink
  • Most common in older people with history of long exposure to sun
• Bowen's Disease (Intraepidermal Squamous Cell Carcinoma):
  • Generally is a reddish-brown scaly patch
  • Usually appears on skin areas NOT exposed to sun and wind and can be caused by some types of wart virus.

Treatment - General

Surgical Techniques

• Technique used depends on individual cases
  
  Curettage with Electrodesication

• Instruments
  • Electric needle
  • Curette (a small sharp loop)
• Procedure
  • Cancer partially scooped out with curette
  • Remaining abnormal cells burned out with electric needle
• Situation
  • Can be performed in doctor's office using local anesthetic
• NOTE: This technique is usually used only for SMALL BASAL CELL
  CARCINOMAS (2 cm or less)
  
  Excision Surgery

• Instrument
  • Scalpel
• Procedure
  • The tumour and a margin of healthy tissue are removed
  • This is the most common method of removal of squamous carcinoma

Micrographic Surgery (Moh's)

• Instrument
  • As for surgery

• Health Professionals
  • Also requires technician, cryostat, trained surgeon
• Procedure
  • The obvious tumour (usually basal cell carcinoma), is curetted to remove the bulk of the tumour
  • A strip is then taken from the edge and bottom for microscopic examination
  • Each strip is examined under the microscope
  • If cancer is still present, sequential strips are taken from that area until the site is clear of cancer
• This is the best method of removal if the edges of the cancer are obviously visible, producing the smallest scar for the highest cure rate
• Requires a great deal of expertise and equipment

Radiation

• May be preferable to surgery if:
  • Surgical excision is not possible
  • The cosmetic result of the surgery would be inferior to that produced by radiation therapy, particularly in older patients.
  • The patient is elderly or at high risk and so considered unsuitable for surgery
  • The radiation effect is localized to the site of the treatment and has no effect on the body apart from the treated area
  • Usually not used for patients under the age of 50 because of poor cosmesis after 10-15 years

Topical (skin applied) Chemotherapy   

• Usage: for actinic keratosis  
• Procedure: topical application of 5 Fluorouracil (5-FU) cream for pre-cancerous lesions for 2 - 3 weeks. This causes the precancer to become inflamed and disappear.  
• Multiple treatment courses are often needed

Systemic (oral or intravenous) Chemotherapy   

• Usage: for those patients having recurrent cancer that cannot be controlled with surgery or radiation  

Other

• Interferon
• Retinoids
• Photodynamic therapy
•  Cryotherapy
• Instrument
  • Liquid nitrogen
• Procedure
  • Liquid nitrogen is applied to the skin area affected to freeze abnormal cells
  • The procedure is repeated two to three times
NOTE: This technique is used only on tiny cancers and pre-cancerous lesions such as actinic keratoses

Basal Cell Carcinoma (BCC)

General Information / Anatomy / Function

• Most common (80 % of skin cancers)
• Begins in the skin cells of the epidermis called keratinocytes
• Grows slowly
• Rarely spreads internally
• If untreated can extend to underlying bone or adjacent skin tissue, causing extensive tissue destruction
• Most patients 45 years and older
• Rare among blacks 

Symptoms / Signs

• Face, neck and upper back are the most common sites
• An ulcerated area with a heaped-up or rolled edge and milky or pearly appearance
• Pale, waxlike, pearly nodule or plaque that may eventually bleed or ulcerate and crust or less commonly as a hard white plaque in the skin, sometimes pigmented.
• Usually does not hurt
• If untreated, it may crust, ulcerate, and sometimes bleed

Etiology / Carcinogens / Risks

• Risk is increased for people with immune suppression
• Slow growing
• Spread by direct invasion
• Can invade bone and cartilage if left untreated (thus the name "rodent ulcers")
• Rarely metastasize   

Squamous Cell Carcinoma (SCC)

General Information / Anatomy / Function

• Less common than basal cell carcinoma
• Starts in the cells of the epidermis called keratinocytes
• Occasionally spreads away from the original location to lymph nodes or elsewhere

Symptoms / Signs

• Face, ears, neck, forearms, back of hands are the most common sites
• Red, scaly, sharply outlined patch or plaque
• Can eventually become a hard, pale pink to white nodule.
• Pre-cancerous changes, called keratoses which look like small white horns or horny patches, may develop into SCC
• Scaly
• An elevated hard nodule, or
• A punched-out infiltrating ulcer, or
• An ulcer with turned-out edges
• May metastasize (spread), especially lesions of ear and lip

Etiology / Carcinogens / Risks

• Most are secondary to chronic sun exposure
• Exposure to high doses of X-rays such as from the X-ray therapy of skin conditions many years ago (will be localized in area exposed)
• Chronic unhealed or poorly healed wounds such as burn scars, or skin ulcers
• Occurs mostly in people in their late sixties and early seventies
• Lymph nodes may or may not be involved but in very late cases widespread metastases may occur
• Verrucous carcinoma is a type of SCC. It is cauliflower-like (fungating) lesion commonly of the foot or penis, and can be secondary to certain types of wart virus.