That makes me very squamous.

Yes I know squamous doesn’t rhyme with squeamish but do I care? Nope. Working in dermatology, skin cancers are a commonplace occurrence in my normal working day. Aside from that they are the most common cancers in the world, though often not as reported. But it makes sense, the skin is a huge organ and always turning over cells. The WHO estimates that 2-3 million non-melanoma skin cancers (NMSC) are diagnosed yearly, that is 1/3 cancers. Melanoma is the one most people have heard of, and for good reason. With a lower incidence, estimated 130,000-150,000 a year, melanoma is a serious killer, literally. But that is for another post. Here, we talk about the squames.

Squamous cell carcinoma (SCC) begins from cells in the epidermis, as opposed to melanocytes (melanoma), or the basal layer (dermis, basal cell carcinoma). SCC is not only skin however, squamous epithelial cells line our hollow organs as well. But for this post I will be referring to cutaneous SCC as cSCC. When the DNA in our skin cells become damaged, hello sunburns, genes are turned on or off and mistakes are made more frequently during cell division. The genes that apply here are mostly those which prevent damaged cells from replicating. Quick point, it is not just sunburn, radiation, HIV/AIDS, HPV, smoking, and many other factors can drive the malignancy that is cSCC. 

Once these changes occur and the cancer takes hold, if the host immune system is not able to detect and destroy the bad cells, it begins to spread. For cSCC it may spread on the epidermis only and does not touch the basal cells. This is cSCC in-situ, and thats a good thing. As in a good thing for cancer, which in this case means the risk of metastasis is very low. Depending on where you look, the rates of metastasis go from 1.5% to 15% (which seems high). This is influenced by a few factors, how thick is the cSCC? Is it on the lips or mucous membranes? Is the host immunocompetent? The risk increased with the poorly differentiated or clear cell types and recurrent tumors. The differentiation of the cSCC refers to the degree to which the cancerous cells look like the OG squamous cells of the epidermis. The poorer the differentiation (generally) the faster the spread. 

The first place it generally spreads are the paretic or cervical lymph nodes, however does have the ability to seed any part of the body. Because of this, it is worth discussion and investigation of suspicious lesions. Ulcerated, friable, red, scaly, looks like a volcano, does not resolve after 1-2 months, bleeds spontaneously  or with gentle touch. In a hospital, nurses should be checking the skin of patients somewhat frequently, and this is a perfect opportunity to be on the lookout. The dermatologists I work with are trained to look closely and make the judgement call, but if you do not bring it up it may never be found. The patient might never have considered getting a skin check. I know that I didn't know what dermatology was a few years ago, other may not either. 

Also think about the population in the hospital. Or maybe you work at an assisted living facility? Or a STI clinic? The patients in these situations have myriad risk factors. Maybe they use biologics for psoriasis, long term steroids for RA, are elderly with a past history of sun burns, or have HIV/AIDS? We cannot go out and stop people on the street, but when they are in our care it is important to be aware of conditions like this. 

Treatment is generally to cut it out, excisions or Mohs, but radiation is popular and for cSCC in-situ, topical chemotherapy and cryotherapy are also used. Combinations of those as well as systemic agents to help reduce the size of tumors in an effort to make them more amicable for surgery. Regardless, early diagnosis and treatment is key (when is it not?). I hope you learned a thing and enjoyed this a little. Please share this with someone you think may also enjoy it, or just someone you hate, and check out the podcast Occasionally Preposterous on iTunes and Spotify. Love y'all. 

References

Image of cSCC on the dorsal hand from the Skin Cancer Foundation.

Metastatic squamous cell carcinoma: a cautionary tale by Shreve et al., in Cureus 2020. 

Squamous cell skin cancer from StatPearls at the NIH National Library of Medicine by Howell and Ramsey.

The CDC website on skin cancer. 

The risk of metastases from squamous cell carcinoma of the skin from the International Journal of Dermatology in 2022 by Caudill et al.

The World Health Organization website on skin cancer.