Photo: Paul Björkman (Sahlgrenska University of Technology)
Basal cell carcinoma (BCC) is the most common form of skin cancer. It grows slowly and almost never spreads to other parts of the body and accounts for around 50-75% of all skin cancers, according to data from the Spanish Society of Internal Medicine. Most basal cell carcinomas are cured, but, without treatment, highly aggressive forms can grow in an infiltrative manner and cause significant morbidity in patients. In addition, its incidence is increasing.
Researchers at the University of Gothenburg have now developed an algorithm that can help healthcare professionals identify patients with a highly aggressive form of basal cell carcinoma on the face, allowing them to directly target the most effective treatment for them.
The study included clinical and dermoscopic images obtained at the Department of Dermatology and Venereology at Sahlgrenska University Hospital. Images from almost 300 patients with confirmed facial basal cell carcinoma were analysed. These images were reviewed by six independent, experienced dermatologists, who interpreted the clinical and dermoscopic findings observed in each case. These findings were used as a basis for the development of a clinical algorithm that serves to discriminate between low- and high-risk types of basal cell carcinoma.
The study highlighted that basal cell carcinomas with an irregular surface had a strong association with the high-risk subtype. In addition, poorly defined borders and the presence of a lighter area (often called the ‘white porcelain area’) were also associated with this high-risk subtype. Small blood vessels in the ulceration were also found to be characteristic of an aggressive form, which was not previously known.
The results of the study are reported in an article in Dermatology Practical & Conceptual and show that the clinical algorithm identifies most cases of high-risk basal cell carcinoma. The algorithm also showed a high positive predictive value, meaning that when it flags a basal cell carcinoma as high risk, it is usually correct.
The best treatment for high-risk basal cell carcinoma
The first author of the study, Hannah Ceder, is a PhD student at the University of Gothenburg and a specialist physician at the Department of Dermatology and Venereology at Sahlgrenska University Hospital. She is also one of the surgeons in the country who performs the surgical method that has been shown to be clearly superior for high-risk basal cell carcinomas.
This surgical method is called Mohs micrographic surgery, which allows for a thorough examination of all tissue margins ensuring complete removal of the tumor while preserving as much healthy tissue as possible. While the patient is under local anesthesia on the operating table, pathologists analyze tissue samples to be absolutely sure that all of the tumor has been removed before closing the surgical wound.
The algorithm would make it easier to determine which tumors can be easily removed with traditional surgery without a prior biopsy and which might require Mohs micrographic surgery.
In other surgeries, there is a risk that the operation may have to be repeated because the pathologist finds residual tumor at the margin of the tumor. “Mohs micrographic surgery gives us complete control of the margins, preserving healthy tissue. In a previous study, we showed that in patients with highly aggressive basal cell carcinoma of the nose, traditional surgery fails to remove the entire tumor in more than half of cases,” says Hannah Ceder.
“It is desirable to develop simple preoperative methods that help physicians identify these high-risk tumors. Therefore, our clinical algorithm is relevant and important. This would make it easier to determine which tumors can be easily removed with traditional surgery without a prior biopsy and which require further investigation to identify cases needing Mohs micrographic surgery” says Hannah Ceder. Nevertheless, it is important to revalidate the clinical algorithm in a prospective setting to investigate its usefulness in a real-world clinical setting, the researchers conclude.
