Introduction to Squamous Cell Carcinoma

Cancer is one of the biggest healthcare concerns today as the number of cancer cases have been increasing rapidly and seem to be able to strike every single part of the human body. Therefore, it is no wonder that our skin, the largest organ in the body, is a big target for cancer and that skin cancer is currently in the spotlight due to its high frequency. Squamous cell carcinoma, or more specifically known as cutaneous squamous cell carcinoma where cutaneous means relating to the skin, is the second most common form of skin cancer. The good news is that squamous cell carcinoma can be prevented and if detected early with prompt intervention leads to very good outcomes and survival rates. However, if left undetected and allowed to progress and spread, it can become life threatening. Therefore, it is important to gain a deeper understanding of this condition and this article serves to provide readers with important information on squamous cell carcinoma.

Risk factors of Squamous Cell Carcinoma

Firstly, it is important to know the risk factors which predispose to squamous cell carcinoma in order to minimize the risk of developing this condition. The biggest risk factor is excessive exposure to ultraviolet (UV) radiation. UV radiation causes mutations to DNA, causing loss-of-function mutation of tumor suppressor genes which are genes that help to suppress tumor formation and hence prevent cancer. One such gene is the p53 gene which helps to repair any damaged DNA, stops the cell cycle to provide time for DNA repair and causes death of cells whose DNA are damaged beyond repair in order to prevent these abnormal cells from propagating. Therefore, loss of function of such genes remove the normal protective mechanism of our body against cancers and can lead to excessive, unregulated growth of abnormal cells in the outermost layer of the skin. This is especially significant in today’s context where beauty trends have led to people pursuing that sun-kissed look. Especially in the West, many achieve their tan by lying out in the sun or resorting to self-tanning products and indoor tanning. This leads to increased exposure to UV radiation and increased frequency of sunburns which can result in squamous cell carcinoma. It is important to note that UV radiation is not just limited to outdoor exposure of the sun as tanning beds also emit UV radiation. In fact, the use of tanning beds is associated with 2.5 times the risk of developing squamous cell carcinoma. Apart from those seeking to get a tan, people living in areas that receive higher levels of UV radiation are also at increased risk of developing squamous cell carcinoma. Countries near the equator are generally exposed to higher levels of UV radiation and one such country is Singapore. Recently, UV radiation in Singapore hit extreme levels which means that more protection is required to prevent sunburns. Hence, it is important that Singaporeans take extra steps to prevent excessive exposure to UV radiation.

Patients who have a weakened immune system such as organ transplant recipients and HIV patients are also at higher risk of developing squamous cell carcinoma. Research has shown that squamous cell carcinoma is 65-100 times more common in organ transplant recipients than the general population. Organ transplant recipients take immunosuppressive medications to suppress their immune system and prevent it from rejecting the transplanted organ. However, this also weakens their immune system’s ability to recognize and fight against tumors, increasing the risk of developing squamous cell carcinoma. Furthermore, these patients are more susceptible to infections such as by the human papilloma virus (HPV) which is said to link to squamous cell carcinoma as well.

Males and the elderly are also more at risk of suffering from squamous cell carcinoma. Statistics show that men are twice as likely to get squamous cell carcinoma than women and squamous cell carcinoma most commonly affects people above the age of 70. The older age group is more commonly affected as cancer is a multistep process and requires an accumulation of mutations. With age, more mutations can be accumulated and there is also more cumulative exposure to UV radiation. Furthermore, there is a decline in immunity with age causing a decrease in ability to fight against tumours. Other risk factors to squamous cell carcinoma also include exposure to ionizing radiation and chronic skin conditions where there is longstanding inflammation, infections, injury or ulcers.

Warning Signs to Take Note for Early Detection

Squamous cell carcinoma can be present in different forms. It can appear as scaly, red, crusty patches which may bleed, raised growths with a central depression, persistent open sores or wart like lesions. It can also develop from seemingly minor and harmless skin changes. If you detect any new moles, growths and spots, any changes in pre-existing moles and spots or any other skin changes which raise suspicion, it is of utmost importance that you consult a doctor. Doing so will allow for early detection of skin cancer if present and will greatly aid in your recovery.

Now that we have covered some of the possible risk factors of squamous cell carcinoma, it is important to know how to detect early signs of the condition especially if you have identified with some of the risk factors mentioned above.

Therefore, it is recommended that you check your skin on a regular basis, observing for any warning signs. The first thing you can look out for is the presence of actinic keratoses. These are scaly, rough, crusty lesions which can be of different colours, typically found on sun-exposed areas of skin. If left untreated, there is a risk of these precancer lesions progressing towards squamous cell carcinoma. As they are more easily felt than seen, you can check for actinic keratoses by feeling for any rough, scaly lesions on sun-exposed areas of skin. Another thing to look out for is Bowen disease which is a non-invasive early form of squamous cell carcinoma. It can be identified by red, scaly patches which tend to be larger than actinic keratoses and affect sun exposed areas of skin or skin of the anal and genital areas.  If left untreated, it may progress to invasive squamous cell carcinoma where the cancer cells now invade past the outermost layer into the deeper layers of the skin.

Other general things to look out for when checking your skin are:

  • Atypical moles which tend to be asymmetrical, have irregular borders, have varying uneven colour, are larger than 6mm and show change over time such as enlargement.
  • A spot or sore that itches, hurts, scabs, crusts, erodes or bleeds
  • Persistent open sores that do not heal within 3 weeks
  • Any skin growths that increase in size

When consulting a doctor, the doctor will ask some questions about your health and examine your skin to check for any skin changes which raise suspicion. However, to confirm a diagnosis of squamous cell carcinoma, a sample of the skin lesion needs to be removed and sent to the laboratory for testing.

There are currently many treatment options available to treat squamous cell carcinoma.

  1. Mohs micrographic surgery.This is done by removing the tumour in stages – excising a thin layer of the tissue and immediately examining it under a microscope to look for cancer cells. If cancer cells are still present, the surgeon will remove another layer at the precise location where the cancer cells are, and the process is repeated until all the cancer cells are removed. This allows for a more targeted and complete removal of the cancer cells, maximizing the sparing of normal tissue and lowering the risk of recurrence of the cancer. Therefore, this is recommended for squamous cell carcinomas that have recurred or have a high risk of recurrence or those with ill-defined borders which makes complete excision of the tumour difficult. Furthermore, as this procedure leaves minimal scarring, it is recommended for squamous cell carcinomas on the face and other cosmetically sensitive areas.
  2. Excisional surgery.An alternative to Mohs surgery which involves excising the tumour along with a safety margin of surrounding normal skin and is often the treatment of choice for lower risk squamous cell carcinomas.
  3. Curettage and electrodesiccation.Where the lesion is scraped off and the tumour site is burned to kill any additional cancer cells. This can be used to treat low risk squamous cell carcinomas that are small and superficial but is not recommended for those that are aggressive and have a high risk of recurrence. This procedure also causes scarring and hence is not recommended to be done on cosmetically sensitive areas.
  4. Cryosurgery.This is done for superficial squamous cell carcinomas and involves freezing the tumour with liquid nitrogen. It is easy to administer with no cutting, bleeding or anaesthesia and hence may be suitable for patients with bleeding disorders or intolerance to anaesthesia. However, it is not suitable for invasive squamous cell carcinomas as cryosurgery may fail to remove the deeper cancer cells and lead to cancer recurrence.
  5. Radiation therapy.It is meant for patients who are not able to undergo surgery or have inoperable tumours. Therefore, the choice of treatment really depends on the severity and location of the cancer as well as many other patient factors. At times, a combination of treatments may be required for more advanced cases of squamous cell carcinoma. Hence, it is important to discuss with your doctor on a treatment plan that is catered to you and your condition.

In conclusion, most squamous cell carcinomas are easily treatable with good outcomes, but prevention is better than cure.  You can start reducing exposure to UV radiation by regularly applying a broad-spectrum sunscreen, avoid tanning, seeking shade and wearing protective clothing against the sun. It is also important to examine your skin every month to look out for any skin changes which may raise suspicion. Such habits need to be cultivated and it is only by doing so can we win the fight against skin cancer.