Why are certain regions of the face at higher risk for bcc?
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Abstract
Despite that basal cell carcinoma (BCC) is curative in the vast majority of cases, some patients are at high risk of recurrence and, in a few patients, lesions can progress to a point unsuitable for local therapy and prognosis is quite poor. The aim of the present work is to review clinical and pathologic characteristics as well as classical and new treatment options for high-risk, metastatic and locally advanced BCC. Surgery and radiotherapy remain the selected treatments for the majority of high-risk lesions. However, some patients are located on a blurry clinical boundary between high-risk and locally advanced BCC. Treatment of these patients is challenging and need an individualized and highly specialized approach. The treatment of locally advanced BCC, in which surgery or radiotherapy is unfeasible, inappropriate or contraindicated, and metastatic BCC has changed with new Hedgehog pathway inhibitors of which vismodegib is the first drug approved by FDA and EMA.
Keywords: Basal cell carcinoma, High-risk BCC, Locally advanced BCC, Metastatic BCC, Mohs micrographic surgery, Hedgehog pathway inhibitors
Introduction
Basal cell carcinoma (BCC) is the most common malignant tumor of the skin and is also the most common human malignancy. The incidence of BCC is increasing in many countries around the world. The underlying cause of BCC is unknown, but ultraviolet light exposure and genetic predisposition seem to be the most significant etiological factors [1]. Aging of the population and frequent exposure to sunlight may explain the worldwide increase that has been observed in the incidence of this malignancy [2].
High-risk BCC
Treatment decisions in patients with BCC are usually made on the basis of an estimate of the risk of recurrence. This estimation takes into account clinical and pathologic prognostic factors associated with a high risk of aggressive behavior and a high risk of tumor relapse after primary treatment with curative intent. Firstly, it should be noted that some important clinical features, such as age, duration of lesion and gender do not define high risk of relapse [11]. On the other hand, clinical features defining high risk of relapse include infiltrative growth margins, size, tumor location, histological subtype, recurrent-refractory tumors and previous history of radiotherapy.
Aggressive, infiltrating tumors are frequently ulcerated and have ill-defined margins [12]. In turn, ulcerated BCC is usually larger than non-ulcerated tumors and may be locally destructive. A size larger than 3 cm has been described as a high-risk feature [13]. Notwithstanding the foregoing, this risk factor has been more accurately defined as 1 cm for head and neck tumors and more than 2 cm in other body areas [11]. Tumor location is important as a prognostic factor and a classification in three groups has been proposed accordingly. Thus, trunk and limbs are considered low-risk areas, forehead, cheek, chin, scalp and neck are intermediate-risk areas and, finally, nose and periorificial areas are high-risk areas [11]. Histological subtype should also be taken into account to establish the risk of relapse. The morpheaform, the sclerosing, the infiltrating, the micronodular and the metatypical subtypes are associated with higher risk of relapse [3, 4, 11, 12, 14, 15] as compared to the risk associated with the superficial and the nodular forms. Perineural invasion has prognostic value and its presence is associated with a higher risk of relapse [11, 12]. In contrast, vascular invasion seems to be of no importance. There is no agreement on the prognostic significance of other factors such as a previous history of radiotherapy, for which a retrospective study found an association [16] whereas others consider this issue as a controversial one [11]. Nevertheless, it is considered that more than 30 % of BCCs have mixed pathology, combining less and more aggressive subtypes (i.e., nodular BCC with areas of infiltrating BCC) [12].
Despite that basal cell carcinoma (BCC) is curative in the vast majority of cases, some patients are at high risk of recurrence and, in a few patients, lesions can progress to a point unsuitable for local therapy and prognosis is quite poor. The aim of the present work is to review clinical and pathologic characteristics as well as classical and new treatment options for high-risk, metastatic and locally advanced BCC. Surgery and radiotherapy remain the selected treatments for the majority of high-risk lesions. However, some patients are located on a blurry clinical boundary between high-risk and locally advanced BCC. Treatment of these patients is challenging and need an individualized and highly specialized approach. The treatment of locally advanced BCC, in which surgery or radiotherapy is unfeasible, inappropriate or contraindicated, and metastatic BCC has changed with new Hedgehog pathway inhibitors of which vismodegib is the first drug approved by FDA and EMA.
Keywords: Basal cell carcinoma, High-risk BCC, Locally advanced BCC, Metastatic BCC, Mohs micrographic surgery, Hedgehog pathway inhibitors
Introduction
Basal cell carcinoma (BCC) is the most common malignant tumor of the skin and is also the most common human malignancy. The incidence of BCC is increasing in many countries around the world. The underlying cause of BCC is unknown, but ultraviolet light exposure and genetic predisposition seem to be the most significant etiological factors [1]. Aging of the population and frequent exposure to sunlight may explain the worldwide increase that has been observed in the incidence of this malignancy [2].
High-risk BCC
Treatment decisions in patients with BCC are usually made on the basis of an estimate of the risk of recurrence. This estimation takes into account clinical and pathologic prognostic factors associated with a high risk of aggressive behavior and a high risk of tumor relapse after primary treatment with curative intent. Firstly, it should be noted that some important clinical features, such as age, duration of lesion and gender do not define high risk of relapse [11]. On the other hand, clinical features defining high risk of relapse include infiltrative growth margins, size, tumor location, histological subtype, recurrent-refractory tumors and previous history of radiotherapy.
Aggressive, infiltrating tumors are frequently ulcerated and have ill-defined margins [12]. In turn, ulcerated BCC is usually larger than non-ulcerated tumors and may be locally destructive. A size larger than 3 cm has been described as a high-risk feature [13]. Notwithstanding the foregoing, this risk factor has been more accurately defined as 1 cm for head and neck tumors and more than 2 cm in other body areas [11]. Tumor location is important as a prognostic factor and a classification in three groups has been proposed accordingly. Thus, trunk and limbs are considered low-risk areas, forehead, cheek, chin, scalp and neck are intermediate-risk areas and, finally, nose and periorificial areas are high-risk areas [11]. Histological subtype should also be taken into account to establish the risk of relapse. The morpheaform, the sclerosing, the infiltrating, the micronodular and the metatypical subtypes are associated with higher risk of relapse [3, 4, 11, 12, 14, 15] as compared to the risk associated with the superficial and the nodular forms. Perineural invasion has prognostic value and its presence is associated with a higher risk of relapse [11, 12]. In contrast, vascular invasion seems to be of no importance. There is no agreement on the prognostic significance of other factors such as a previous history of radiotherapy, for which a retrospective study found an association [16] whereas others consider this issue as a controversial one [11]. Nevertheless, it is considered that more than 30 % of BCCs have mixed pathology, combining less and more aggressive subtypes (i.e., nodular BCC with areas of infiltrating BCC) [12].
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