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SKIN CANCER
(nonmelanoma)
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SKIN CANCER
(nonmelanoma)
What is Skin cancer?
The skin is a tissue, meaning that it is a collection of cells organized as a unit. Normally, skin cells divide to replace ones that have died either from old age or injury. New skin cells arise at the deepest level of the skin, and gradually push their way upwards toward the surface as they mature.
The main types of cells found within the skin are basal cells, which form the bottom layer, squamous cells, which push toward the surface to form the skin we see, and melanocytes, which produce melanin pigment that colors the skin. Any one of these types of cells can give rise to skin cancer, when their reproduction goes out of control, and they divide in a disorganized way. When basal or squamous cells become cancerous, they are called carcinomas, while when the melanocytes become cancerous, this is called melanoma, which has such a different character that it is another topic.
As above, the skin is made of various cells, including basal cells, squamous
cells, and melanocytes. Normally these cells divide very quickly in womb life, early
childhood and through puberty to grow the adult body. In adulthood, the middle and
upper layers of skin will grow to repair an injury or to replace cells which have died of
old age. If the basal (underlying) layer is damaged, as in a third degree burn, then
the skin must be grafted to heal properly. Like all body cells, the division of skin
cells is under very tight control, by the genetic material ("genes") within each cell.
When certain damage occurs within these genes, control over ordered cell division
may be lost, and the nature of these cells dramatically changed. Any type of skin
cell can give rise to skin cancer, if it's reproduction goes out of control, and it divides
in a disorganized way. Skin cancer, like any type of cancer, starts in just one single cell . The abnormal cells may pile up in a clump, called a "tumor" . A tumor simply means a swelling, which can be caused be infection or many other
non-cancerous conditions. A tumor which merely grows in it's local area, and cannot spread distantly
to other body areas, is called"benign" and isn't cancer. Most lumps and bumps (tumors) found within the skin are benign
. In contrast, a tumor which can spread
to distant body areas (whether it actually does or not) is called"malignant", and this is cancer . The process of spread is called "metastasis" . A cancer which starts within the skin is called a "primary skin cancer" . Just because a cancer is found on the skin does not prove it originated there;
it may have started somewhere else (e.g. lung, breast, kidney) and metastasized to
the skin. It is this capacity for spread, both local and distant, which makes any
cancer so dangerous. When basal or squamous cells become cancerous, they are calledcarcinomas, while when the melanocytes become cancerous, this is called melanoma, which has such a different character that it is another topic.
How Common is Skin Cancer?
Skin cancer is the most common cancer in the United States, with over 500,000 new
cases each year causing 3,800 deaths . The number of cases has increased each year. The most common type of skin cancer is Basal cell carcinoma (BCC) which is 75% of skin cancers. Squamous cell carcinoma (SCC) makes up 15% of skin cancer, while the remaining 10% are melanomas, and variant types
of BCC and SCC. Other very rare cancers arise from sweat glands or touch and temperature
receptors in the skin. Some come from immune cells in the skin ("lymphomas") . Skin is a common area for other organ cancers to metastasize to, because of it's
large surface area and good blood supply. These have much different natures and
therapy than "primary skin cancer", and are discussed in their own reviews.
How is Skin Cancer Diagnosed and Evaluated?
Whenever a patient develops an area suspicious for skin cancer, they should report
it to their physician. Moreover, ideally a general physician should examine every
square inch of a patient during an annual physical exam, to detect "lesions" (abnormal areas) that the patient hadn't noticed. It is not uncommon for people to
miss areas of their scalp, back, gluteal fold (between the buttocks), perineum (between
the genitals and anus), and backs of thighs since our eyes are not well positioned
to see these places. A person should not feel embarrassed at pointing out something
"troublesome" in even the most private area to their doctor-- if so, they
should find a new doctor whom they are completely comfortable with. Most lumps in
the skin are due to infection, scarring, fatty changes ("fat necrosis"), or other
benign tumors. "Lipoma" is the medical name for a benign fatty skin tumor, which may at first grow quickly and then remain unchanged for years. That's what
Abraham Lincoln had on his face, as many adults do.
While new lumps or appearance changes in the skin may suggest cancer, the only
certain was to diagnose any cancer is by taking a sample of it, called a"biopsy". The
biopsy material is examined by a "pathologist", a physician specializing in diagnosing disease using tissue samples. A biopsy may
be done by removing the entire suspected cancer, with a safety margin of normal tissue
around it. This is called an"excisional biopsy". Alternately, just a small sample of the tumor may be taken, either by cutting a piece
off of it or using a punch device to take a core of it. This is called an"incisional biopsy" and is used for either large tumors, those of sensitive cosmetic areas like the face,
or those for whom the suspicion of cancer is very low. The biopsy material is studied
by the pathologist using special stains, which highlight the process of rapid cell
division common to cancer. (S)he will identify the cell of origin of the overgrown
tissue, and may subject the biopsy material to immune or gene tests to help determine
whether it is "benign" (shows no evidence of cancer) or "malignant" (cancerous). If the tumor is malignant, the pathologist will then specify the name
of the particular cancer, based upon the cell of origin. If an excisional biopsy
was performed, with the goal of removing the entire tumor, (s)he will look at the margins (edges of the removed specimen) to be sure that they are "clear" or free of any cancer
cells. This procedure makes the diagnosis of cancer, and if a "full thickness" biopsy
was obtained, it gives an idea of how deeply the cancer penetrates.
Once cancer is detected, the next step is to evaluate how extensive it is. Fortunately,
skin cancer has less tendency to spread
than any other cancer, accounting for it's excellent cure rate. Spread, that is metastasis, of the most common type, BCC, is exceeding rare and so doing extensive tests to look it elsewhere in the body
is unwarranted
. However, the cancer can grow downward to penetrate into the subdermis, so it is
important, for treatment, to know how far it has spread locally, both along and beneath
the skin surface. Spread to even local lymph nodes is seen in less than 1% of patients, but a nearby swollen lymph node ("lymphadenopathy") must still be checked if any
suspician exists. Note that local infection can swell lymph nodes.
Spread to lymph nodes is somewhat more common for theSCC type, especially if it starts in the face or scalp, where it has a predilection to go to lymph nodes around the parotid gland (which
makes saliva). Thus it is appropriate to get a CT scan of the head and neck to look
for these enlarged lymph nodes; if they are found they need to be surgically removed.
The CT scan is basically a computerized combination of multiple X-rays to reconstruct
a multiple 2-dimensional slices of a body area, which can be combined in the viewer's
mind to provide a 3-dimensional image of that area. CT scan is useful for picking
up tumors or enlarged lymph nodes larger than 1 cm.
The Cancer Group Institute material describes the frequency, risk factors, symptoms, evaluation, staging, conventional treatment and results, and the latest treatments and results for skin cancer. We tell you every thing you need to know to deal with a skin cancer problem.
