Skin cancer is defined as the uncontrolled growth of cells that is happening within the skin. There are 3 main types of basal cell carcinoma, squamous cell carcinoma, and melanoma. Some skin cancers can spread to other locations in the body and can be fatal. The skin is divided into 3 layers: the epidermis, dermis, and the hypodermis. The hypodermis is made of fat and connective tissue that anchor the skin to the underlying muscle. Just above is the dermis which contains hair follicles, nerves, and blood vessels. And just above that, the outermost skin layer is the epidermis.
The epidermis itself has multiple skin layers that are mostly keratinocytes, which are named for the keratin protein that they are filled with. Keratin is a strong fibrous protein that allows keratinocytes to protect themselves from getting destroyed, like when you rub your hands through the end of the beach. Keratinocytes start their life at the deepest layer of the epidermis called the stratum basale or basal layer, which is made up of a single layer of small cuboidal to low columnar stem cells that is been continually dividing and producing new keratinocytes which usually continue to mature as tend to migrate up through the epidermal layers, flattening out to a pancake-like squamous shape as they ascend. But the stratum basale will usually contain another group of cells called melanocytes which usually secrete a protein pigment or coloring substance which is known as melanin.
Melanin is actually a broad term that constitutes several types of melanin found in people of different skin colors. If we look at the subtypes of melanin range in color from black to reddish-yellow the relative quantity, as well as the rate at which they tend to metabolize, will usually define a person’s skin color. When keratinocytes are exposed to the sun they send a chemical signal to the melanocytes, which stimulates them in making more melanin. Melanocytes usually tend to move the melanin into small sacs which are called melanosomes. These get taken up by the newly formed keratinocytes which will later metabolize the melanin as they migrate to the higher layer of the epidermis. Melanin will then usually act as a natural sunscreen, this is because the protein structure dissipates or scatters the UVB light which if left unchecked will tend to damage the DNA of the skin cells and lead to skin cancer. Melanocytes can also be found in the dermis at the base of the hair follicle where they transfer melanin to the keratinized cells that make up the hair.
Now a tumor develops if there is a DNA mutation in any of these cell types that leads to uncontrolled cell division. Typically these are mutations in the proto-oncogenes which results in the promotion of the cell division or mutations in tumor suppressor genes which results in the loss of inhibition of cell division. You can think of proto-oncogenes as the accelerator or the gas paddle and tumor suppressor genes as the breaks. Too much acceleration or inability to break can lead to runaway cell division. As a result, the mutated cells can start pilling upon each other and become a tumor mass. Some of these tumors are benign and they stay well contained or localized. But some can become malignant tumors or cancers and these are the ones that can break through their basement membrane and invade nearby tissues. The malignant tumor cells have a tendency to get into nearby blood or lymph vessels and thereby travel from the primary site in order to establish a secondary site for the tumor growth somewhere else in the body and that is called metastasis.
Skin cancer is differentiated based on the type of skin cell that is involved in the tumor mass. The most common is the basal cell carcinoma which involves cells in the stratum basale. These tend to be slow-growing tumors that can be locally invasive but rarely metastasize to distant regions of the body. Nearby blood vessels in the dermis can become dilated to deliver more nutrients as the tumor grows. Basal cell carcinoma can grow superficially, spreading over several centimeters of the epidermis. And making the breakthrough the basement membrane and invade the dermis forming islands or cords of tumor cells. Tumor cells on the periphery of islands typically arrange themselves in a line, like a fence post forming a palisading pattern. If we see the second most common type of skin cancer it is none other than the squamous cell carcinoma which involves squamous keratinocytes. Now a precancerous lesion that can turn into a squamous cell carcinoma is called actinic keratosis. In actinic keratosis, keratinocytes are damaged by radiation and benign to overproduce keratin. Over time these damaged keratinocytes can develop into squamous cell carcinoma. In an early stage of squamous cell carcinoma is also called Bowen’s disease or squamous cell carcinoma in situ.
At this point, the tumor can be found in the epidermis but it has not broken through the basement membrane. Tumor cells are typically enlarged and over pigmented. As squamous cell carcinoma becomes more invasive, it can break through the basement membrane and extends into the dermis. It may even reach the hypodermis, at which point it is more likely to metastasize. Tumor cells at these more advanced stages typically vary in the degree of maturity, have abnormal shapes, and overproduce keratin forming pearls. Finally, the most aggressive form of skin cancer is melanoma which involves melanocytes. Now melanocytic nevus more commonly known as a mole results from a type of melanocyte that overproduces melanin. These moles can be considered precancerous because they carry an increased risk of becoming a melanoma. Melanoma grows horizontally within the epidermis and superficial dermis and they grow vertically invading the dermis.
Metastasis is most associated with the depth of invasion and in fact, melanoma is the most deadly form of skin cancer because of its tendency to metastasize more quickly. Typically the tumor cells have large nuclei with irregular contours and produce melanin in a variety of colors brown, red, dark blue, and gray. The causes of skin cancer can be both genetic and environmental. By far the leading environmental factor is the UV exposure from the sun or tanning booths. Often the risk of developing skin cancer increases as the sun exposure over a lifetime accumulates. Some viral infections like human papillomavirus immunosuppression and having light skin also tend to increase risk. Skin cancer typically appears on skin that is exposed to the sun. Basal cell carcinomas can appear as well-circumscribed, pearly, waxy, or shiny solid elevation of the skin. They can also be ulcerated in red or pigmented. Actinic keratosis can appear as dry, rough almost sandpaper-like patches that are surrounded by tan, brown, red, or flashed colored skin. They tend to commonly form on the lips, face, scalp, arms, ears, and back of the hands. Squamous cell carcinoma can appear as a small well-circumscribed red elevation of the skin with scaly plaques on the top which can sometimes ulcerate. Moles can appear as small, oval, tan, pink, black, or brown spots that can be flat or elevated.
Finally, the worrisome signs of melanoma can be remembered using the mnemonic ABCDE where legions are asymmetrically shaped, borders are irregular or notched, correlation varies within the same legion. The diameter is larger than the size of the pencil eraser and the legion rapidly evolves over time and can cause skin elevation. These lesions may also be itchy or painful. A tissue biopsy is needed to make a definitive diagnosis of skin cancer and treatment options include removal with surgery or with cryotherapy where the tumor is frozen off. Radiation, chemotherapy, or immunotherapy may also be considered as options. In precancerous cells like in actinic keratosis or melanistic nevus are typically removed to prevent their progression to skin cancer. With cryotherapy or photodynamic therapy, which is where light is used to induce cellular death.
(Image to be added soon)
Skin cancer is so common, nowadays the basal cell skin cancer which is by far the most common not just skin cancer but the most common cancer period. There are more than 2 million cases in the US alone. So we can say skin cancer is on the rise and whether that is because we are doing a better job at deducting it or it is true to increase the incident. It is probably a combination of both. For a person, the most important thing that they can do to prevent skin cancer is to cover up from the sun. Like much other cancer, we know what causes skin cancer we know the damage occurs from UV radiation from the sun. So the best thing that you can do is to protect yourself and cover-up.
There was nothing that we could have done when we were children to see if the parents have put the sunscreen on us or not, which is beside the point. But from here on out it is better to be informed that staying out of the sun during peak sun hours. If you are going to be outside and you know you are living your life outside, we just need to be smart and cover-up, seek shade, wear a hat, wear long sleeves. Even an ounce of prevention is certainly worth a pound of cure. We need to educate the people of the ABCD’s of skin cancer.
Where A is for asymmetry, you know any spot that you can’t run an imaginary line down and have it be symmetrical on both sides. Any kind of asymmetry should be a cause for concern and should certainly warrant a dermatologist keen eye. B is for borders, any moles or spots that you have should have a really smooth nice even border. They should not be fuzzy or irregular, any mole or any spot with a very irregular border again is a cause for concern. The C stands for color variation, so most moles should have a nice even pattern where there are nice soft shades whether light or dark should be an even shade. If there are any color variations, you are seeing pinks and browns that certainly will be a cause for concern. And D is diameter, most spots are not going to cause any trouble, nor the moles will if they are under 5 or 6 millimeters, which is about the size of a pencil eraser. So anything smaller than the pencil eraser is said to be ok. Once the diameter of the mole gets above that, then you should start to think about seeing the dermatologist.
The general tips at what you want to see the dermatologists. Doctors usually tell the patients to look out for the things that are changing. Like the change in color, size, symptom, earlier it might not feel anything and now it is starting to be painful or itchy. Consider something that is not healing in a few weeks, you definitely need to see a dermatologist get that checked out. There are definitely certain things that will put you at a higher risk of getting skin cancer. One is if you are fair-skinned or you have light hair, light eyes and if it is hard for you to tan, so if you are usually burning if you have had blistering sunburns in the past. That will put you into a little bit of a higher risk, even if you had skin cancer you are at a higher risk, and if you have someone in your family who has skin cancer. One more thing that puts you at a higher risk of skin cancer is the indoor tanning.
So this is even if you did it once when you were in college, that still puts you at a higher risk because of the concentrated UV radiation that you are getting in those sessions and that would be something where you would want to come in and see the dermatologist get a full-body skin checked. There are 3 main types of skin cancer: non-melanoma skin cancer, basal cell cancer, and squamous cell cancer. then there is melanoma. Basal cell cancer is the most common cancer and that is the thing that you are most likely to have. That type of cancer is very rare to spread to other parts of your body, but it is very important to get tested and to treat after the biopsy because it can grow and invade local structures and cause local damage. Squamous cell cancers are kind of a little bit up from the basal cell cancers and how aggressive they are and they can spread from place to place. Especially if they have certain high-risk features and then we have melanomas which are the most serious types of skin cancer that can spread to different types of your body and is something that needs to be treated aggressively.
If we hope to catch an early stage where all we have to do is cut it out, but sometimes it is passed then and then we are going to be working with an oncologist and we need to come with the best treatment plan. Every dermatologist does it differently, as some go from head to toe and then look into the scalp and check if there is anything to be concerned about. Looking closely at the face, the arms, the chest, your back, then looking at all the legs, and sometimes the doctors ask to be looked at the genitals because for a lot of women that happens at the obedient as well, so, as the skin cancer can occur anywhere there is skin. The doctors will examine the buttock, looking inside the mouth, looking at your eyes, and even examining the area in between your toes as well as the bottoms of your feet. The doctors will be looking at all of the different spots that you will be having that you may have noticed which have come up. They will be even looking at the textural changes that sometimes tell there is a pre-cancer. Looking for the spots that maybe you have not noticed that is not healing.
1. Does skin cancer depend on skin color?
The fairer your skin the higher your chances of getting skin cancer and the darker your skin the lower the chances of you getting skin cancer. However, all skin types and all races can be affected by skin cancer.
2. How does skin cancer affect men and women?
Skin can affect men and women differently, for example, men are more likely to get skin cancer on the head, shoulders, and upper body. Whereas the females see skin cancer on their lower legs. An interesting fact about skin cancer is that not all types of skin cancer arise from moles. So when you examine your skin, you should not just look for the moles but for the other areas of skin that may be changing the shape, size, or color.