Introduction
Cutaneous squamous cell carcinoma (CSCC) is the second-most common neoplasia in humans after basal cell carcinoma; about 1.2 million new cases of head and neck skin cancer are estimated in 2040, with 680,000 deaths.1 In Brazil, 173,930 new cases of non-melanoma skin cancer are estimated in 2020, with about 2,000 deaths2. Approximately 80% of CSCCs are located in the head and neck region and advanced CSCC have a mortality rate of 20%, although this value may have been underestimated due to the lack of precise data in developing countries in South and Central America.
Advanced CSCC is defined as locally invasive in deep anatomic structures with or without presence of regional or distant metastasis; nominated as locally advanced (laCSCC) and metastatic (mCSCC); classified as T3/T4, stage III or IV, where no parotid and locally treatment standards are stablished; the relapsed CSCC (reCSCC) is defined as multiple recurrences after successfully margins free resection6. The estimated incidence was 8.000 cases of nodal metastasis and 3.000 deaths annually for both laCSCC and mCSCC whose still are in a standardized area of unmet medical need7.
The recommendations of treatment are based on literature review and guidelines, generally, primary surgical excision with safety margins and the appropriate lymph nodes chain dissection are necessary on the proven positive regional metastasis or in the high risk patient, but still, debate exists in the clinically negative neck and the extension of the parotidectomy 8 .
The incidence of parotid metastasis from CSCC is not common, occurring in 1% to 5% of all cases of CSCC in the head and neck region and regional metastasis can occur up to five years after resection of the primary 3-5. The high-risk clinical features for parotid and neck metastasis from CSCC include size (T); depth; scalp, ear pavilion; immunosuppression; recurrence; poor differentiation and others 9-12. Recently the immunosuppression induced by drug delivery to organ transplants patients, to those with autoimmune diseases and other clinical comorbidities (diabetes mellitus), has been recognized as an important risk factor for the development of CSCC, with growing incidence and mortality in the world 13,14.
Parotid metastasis from CSCC has an unfavorable prognosis, with lower survival, higher incidence of locoregional recurrence, high extracapsular spread and occult neck metastasis; however, there are few information about the biological tumoral spread from parotid to neck nodes 5,11,15-17. There are some parotid and neck staging systems, denominating it as positive (P+) or negative (P0); or the N1S3 classification, which does not have consensus worldwide. At present, the most accepted system is the TNM system, although the pN staging evaluation is directly affected by surgical technique, dissection amount, and the quality of pathologic examination18-22.
To the present, no consensus exists regarding the parotid treatment and the indication and extent of neck dissection in the reCSCC and laCSCC; the identification of the risk factors for parotid metastasis in reCSCC and la CSCC can allow selecting the proper treatment approach for the parotid gland and to the neck dissection.