Skin is the largest organ in human body, quiet naturally making up 16% of the body weight,
with a surface area of 1.8 m. This phenomenal organ protects the body against heat, sunlight,
injury and infections; helps in controlling the body temperature and stores water and fat. Skin
cancer is the most common type of cancer wherein areas of skin exposed to sunlight become
the most popular region affected, though it can occur anywhere on the body. Historically,
"Mummies" more than two thousand years of age have been found to bear signs of skin cancer.
However, John Hunter was the first surgeon to perform successful excision of melanoma tumour
in 1787; and Rene Laennec, a French doctor was the first to clinically distinguish melanoma in
1804.
Conventionally, the wise explanation for incidences of skin cancers being lower among
Indians is due to the protective effects of melanin; an effect which lacks in the ethnic
groups of hispanics and non-hispanic whites who showed an annual incidence rate of
melanoma to be 4 per 100,000 and 25 per 100,000, respectively. It is so predicted that
1 in 5 Americans will develop skin cancer in the course of their entire lifetime. Cancer of
any form has been dreadfully eating away human existence in a slow but definitive pace
and over the past three decades, more people have had skin cancer than all other cancers
combined.
Light skinned terror
The body is made up of trillions of living cells. Normal
body cells grow, divide and die in an orderly fashion.
Cancerous cells are characterised by uncontrolled cell division and become immune to
the apoptotic pathway Further tragedy in this clinical condition is the ability of these
cells to travel to other parts of the body forming new tumour, termed "metastasis".
The epithelial outburst most often developed on the skin exposed to sun results into skin
cancer
The skin has three layers namely, the epidermis, the dermis and the subcutis. The epidermis
is the topmost layer of skin protecting the deeper layers of skin and organs of the body from
external environment. The main type of cells in epidermis is basal, squamous and melanocytes;
and each of them are susceptible to developing into cancerous type, on the basis of which the
entire spectrum of skin cancer is clinically defined. Let us now discuss the two major types of
skin cancer and their impact on population.
Non-melanoma skin cancer (NMSC)
Incidences of skin cancer have been on the rise since the last few decades worldwide
wherein Non-melanoma skin cancer has been diagnosed to be the most common variety Though national
survey and cross-country data in India is unavailable, the smaller collated reports
indirectly indicate a possibility in rise of Non-melanoma skin cancer in Indians.
- Basal Cell Carcinoma (BCC) Basal cells form the lowest layer of the epidermis that
constantly divides and replenishes the skin layers. This abnormal uncontrolled division
of cells causing lesions is so common that about 8 out of 10 skin cancers belong to this
type. Basal Cell Carcinoma, a rare in darkskinned individuals, develops on the skin that is exposed to sun,
majorly regions like the head, neck and back of the hands. It appears like open sores, red
patches, shiny bumps or scars that are usually caused by intense, occasional sun exposure.
Typical Basal Cell Carcinoma is indolent with slow progression and has a limited potential to metastasise,
but at times can cause extensive local destruction. Ultraviolet (UV) radiation from the sun
is accepted to be a critical causative factor, apart from the other predisposing risks like skin
type, red or blonde hair, blue or green eyes, freckling or sunburn in childhood, family history
of skin cancer, immunosuppressive treatment, etc.
- Squamous Cell Carcinoma (SCC)
The second most common type of the non-melanoma skin cancer, accounting for about 2
of the 10 affected is the Squamous Cell Carcinoma and commonly appears on sun-exposed areas of the body such
as the face, ears, neck, lips and back of the hands. Actinie keratosis is a precancerous skin
condition where rough scaly pink-red spots are observed due to continuous exposure to sun
and Bowen disease also termed Squamous Cell Carcinoma in situ is the earliest form of Squamous Cell Carcinoma showing reddish, scalier
and crusted patches. Daily year around exposure to sun's UV light, intense exposure in the
summer months, use of tanning beds add to the damage that results in squamous carcinoma.
- Other less common non-melanoma skin cancers
Merkel cell carcinoma - This neuroendocrine carcinoma is most often seen in older people.
Kaposi sarcoma (KS) - It is caused due to infection by the KS agent or the Kaposi sarcoma associated human herpes virus (KSHV) affecting the cells which line the lymph or blood vessels.
Cutaneous lymphoma - A type of cancer of the immune system primarily involving the skin.
Skin adnexal tumours - These begin in the skin glands or hair follicles.
The ones above are very rare and together account for < 1% of all skin cancers across the world.
Melanoma skin cancer
Melanoma is a more severe type of skin cancer beginning in the melanocytes, also called as
malignant melanoma or cutaneous melanoma. These tumours are distinctly brown or black
due to the melanin produced by melanoma cells.
Although, it accounts for less than 2% of skin cancer cases, it causes majority of skin
cancer deaths. This condition is 20 times more common in whites than in African
Americans and its risk of occurrence increases as people age. The risk factors vary
from alterable ones like smoking and sun exposure to the unalterable ones like person's
age and family history of skin cancer. UV rays are majorly the cause for melanoma, where
these cause extensive DNA damage
triggering cancer. With a prevalence of about 10% in human population, familial melanoma
is character ised by alterations in the tumour suppressor genes such as CDKN2A and CDK4
leading to uncontrolled cancerous growth. Many other genetic mutations have been deciphered,
some of which have been proved to be good targets for drugs to help treat this disease, a well-
known procedural target therapy treatment. At the molecular level, events for developing skin
cancer include the ultraviolet B (UVB) induced MAPK signalling pathways where UVB signals
MAPK cascade which through a series of signal transduction cascade causes proliferation,
differentiation. apoptosis or tumourigenesis." UVB irradiation produces DNA damage causing
faulty cellular response. Also, p53 tumour suppressor gene that crucially maintains DNA
replication gets mutated due to UV-induced carcinogenesis developing into skin cancers.
Other factors like loss of heterozygosity observed on chromosome9q22 with inactivating
PTCH (Patched tumour suppressor gene) mutations have been found in patients with BCC.
Vital signs-to detect skin abnormalities!
Early diagnosis is essential in spotting the cancerous growth & looking out for warning signs
on the skin (i.e. new spots on skin) is a critical step to approach the doctor sooner than later.
Development of moles at birth, during childhood or young adulthood is common and harmless,
but certain moles change their size, shape or colour and these unusual moles, sores, lumps,
blemishes, markings or changes in the way an area of skin feels are some early indications
of melanoma. The ABCDE rule to identify for usual signs of melanoma is a must:
ABCDE in skin cancer stands for:
- Asymmetry - One half of a mole or birthmark does
not match the other.
- Border - The edges are irregular, ragged, notched or
blurred.
- Colour - The colour is not the same all over the mole; may include shades of
brown or black, sometimes with patches of pink, red, white or blue.
- Diameter. The spot is larger than 6mm across.
- Evolving - The mole is changing in size, shape or colour
Although some melanomas do not fit in the ABCDE rule, being vigilant about evolving
new spots with varying growth and appearance can save the severity which cancer
otherwise brings in life.
Fightback the terror As mentioned above, early diagnosis of skin cancer is the key for effective
treatment before it spreads deeper into other organs. As in case of BCC, wherein symptoms
resemble non-cancerous skin conditions like psoriasis and eczema, a skin specialist's consultation
is an immediate and a must initial step to be taken. BCC and SCC are diagnosed by the specialist
based on the presence of symptoms and physical examination. Most suspected cases of skin cancer
are generally highlighted by the patient themselves or their family members, wherein the physician
along with physical examination and medical history, considers even the patient's past exposure
to sun to drive into a conclusion. These preliminary examinations are generally followed by a
recommendation for a skin biopsy, the most convenient method to diagnose and categorise the
type of skin cancer
Numerous treatment options are available to deal with cancer at an early stage: the decision
for which is based on the type, risk of recurrence, patient's age, general health and medical
history. Options like Curettage and Electrodesiccation, Cryosurgery, Mohs surgery are preferred
to treat SCC and BCC. Based on the severity to treat effective high-risk carcinomas, large tumours
and recurring tumours, Radiation therapy, less common Topical Chemotherapy and Laser therapy
are considered. The well-known topical treatments involve use of fluorouracil (5-FU) or imiquimod
for a duration of three to six months. In case of melanoma, treatment is done in stages starting `
with surgical removal of tumours, lymph node biopsy, or radiation therapy followed by
continuous clinical trials to reduce the chance of recurrence. Recent research in melanoma
has aimed for developing personalised radiation treatments as the patients are pre-evaluated
on the genetic front and classified.
Research and evidence indicate atmospheric ozone depletion
increases the levels of radiation at the earth's surface, thereby increasing the risk of skin cancer:
UVB radiation harbour's the most important wavelengths for severe DNA damage thereby inducing
skin cancer: Mathematical models suggest an increase in incidence rate of skin cancers by 2-4% for
every 1% depletion of the ozone layer, more so for SCC which is a concern. Although Indian
population is supposedly protected under the effect of melanin, smaller pool of studies conclude
Indians are predominantly affected by SCC; an epidemiological characteristic that sets us apart
from the global trend where BCC is dominant. Early research suggests that Vitamin D has the
potential to be used as the starting point of drugs to treat skin cancer; vitamin is known to
break down the network of proteins linked to development of BCC thus possessing anti-cancer
abilities and research on these grounds is under trials. Today, the drastically elevating incidence
of skin cancer needs our scrutinised attention as early detection is the simplest way to combat this
dreadful menace! Skin protects our body. It's time we return the favour and save it from the sun's
glare!
