Epidemiology of orofacial malignancies in Egypt (2016-2021): A reappraisal account

Introduction

There is no straight way for reporting the epidemiology of orofacial malignancies worldwide given the inconsistency in reporting cancerous lesions[1–4] and the continuous reappraisal of the histomorphologically similar lesions that proved to be cytogenetically separate entities (e.g., acinic cell carcinoma and mammary analog secretory carcinoma[5–7]). Complicating the matters, the introduction of new orofacial lesions (e.g., Adamantinoma-like Ewing sarcoma of the salivary glands[8,9], mammary analog secretory carcinoma[10–14], Renal Cell-Like Adenocarcinoma [15–17], HPV-related multiphenotypic sinonasal carcinoma, with adenoid cystic carcinoma-like features[18–22], Microsecretory Adenocarcinoma[23–27], ossifying fibromyxoid tumor[28,29] and Oncocytic intraductal carcinoma [23]) could not be mastered by all head and neck pathologists even in the USA[30]. Several epidemiologic efforts have been exerted to report orofacial malignancies in Libya, UAE[31], Saudi Arabia[2,32] and other Middle Eastern countries [33]either at the uni-institutional level or at the multi-institutional level[34].

This study reviews the available statistics about the total number of reported malignancies between 2016 to 2021, their mortalities and the percentage of orofacial malignancies at the national level. It also investigates the pathologically established diagnosis of orofacial malignancies in Cairene health institutions.

 Method

We examined the annual bulletins and detailed reports of Health Services published by Central Agency of Public Mobilization and Statistics [35] and the pathology departments of major public health institutes in Cairo. The Kaplan–Meier method with confidence interval and Log-Rank test are used to calculate the survival analysis for the five studied groups: Group 1: hematological lesions (HL), : Group 2: oropharyngeal cancers (OrC), Group 3: nasopharyngeal cancers (OrC), Group 4: odontogenic malignancies (OD) and Group 5: salivary gland malignancies (SG). The event of interest (Dt), censored event (Ct), proportion surviving interval (Pt), and cumulative survival (St) are illustrated.

 Results

The number of reported malignancies in Egypt from 2016 to 2021 are 201192, 205064, 238044, 256371, 284209 and 338499, respectively (Table 1). Of these malignancies, orofacial malignancies ranged from 3.546 % to 9.6639%. During the COVID-19 pandemic, the rate of mortality of orofacial malignancies decreased (Table 2). Yet, the survival rate for the five studied groups was constant (Figure 1).

Table 1. Total number of reported orofacial malignancies in Egypt (2016-2021).

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Table 2. Number of reported orofacial malignancies in Cairo (2016-2021)

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Figure 1. Survival rate in the five studied groups.

Although squamous cell carcinoma is the most common malignancy of the orofacial region, tumors originating from hematologic and salivary origins are also frequent (Table 3). However, the survival rate of these salivary malignancies is most favorable.

Table 3. Percentages of orofacial malignancies in Cairo sorted on frequency (2016-2021).

The most common salivary gland lesions are mucoepidermoid carcinoma, representing 21% of all salivary gland malignant tumors. The other frequent salivary gland cancers are adenoid cystic carcinoma (20%), acinic cell carcinoma (12%), adenosquamous cell carcinoma(11%), and carcinoma ex-pleomorphic adenoma (6%). Warthin tumor was frequently associated with acinic cell carcinoma, carcinoma ex-pleomorphic adenoma, salivary duct carcinoma and mucoepidermoid carcinoma. Although the variants of each neoplasm were not defined, the grading of the majority of salivary gland tumors was low-grade.

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 Discussion

The classification of orofacial malignancies is not always standardized. The majority of Egyptian oncologists follow the 2005’s WHO classification[36], which does not include many of the newly described pathologic entities in the newer versions[37]. Given the lack of facilities needed for performing molecular investigations (and sometimes the basic immunohistochemical workup), the final diagnosis diagnosis diagnosis is inconsistent with the standardized diagnostic protocols.

Consistent with the literature, there were some multifocal incidences, synchronous and metasynchronous occurrences of malignancies either at the same topography or affecting more than one site[38–41]. The collision lesions, associations and syndromic relations are always underdocumented. For example, Warthin tumor was frequently reported with salivary gland malignancies. However, the cancerous condition is only highlighted. If a patient suffered from two synchronous lesions, one of them is provided. This under-investigation may pose questions regarding the accuracy of the final diagnosis, especially if the morphological pattern of the diagnosed lesion is not straightforward[42–45].

The numbers retrieved in this study must be used with extreme caution because no unified database links the Egyptian health institutions. Even death certificates do not include all designations of cancers. For example, multiple myeloma (or plasmacytoma) is not included in the hematological malignancies. Therefore, the deaths due to this neoplasm is usually recorded either as lymphoma or leukemia. Another limitation to the accuracy of the reported numbers is that the records do not specify the primary origin of the tumor and the different sites of metastases. This challenges the proper diagnosis[46]. Moreover, the clinical, radiological and confirmatory investigations are always missing. Moreover, the initial diagnosis is not given, heightening the impression that the diagnostic accuracy of all Egyptian oncologists is 100%. Moreover, the dates of the initial diagnosis, disease onset and seeking therapeutic interventions are always dropped.

Conclusion

Orofacial malignancies ranged from 3.546 % to 9.6639%. During the COVID-19 pandemic, the rate of mortality of orofacial malignancies decreased. Yet, the survival rate for the five studied groups was constant. Head and neck pathologists must incline to examine the biopsies carefully because the survival rate of what seems to be histomorphologically similar corresponds to different survival rate and warrants different therapeutic interventions.

 Future studies should investigate demographic variables (gender, territory, economic status, health habits, education and occupations) and the frequency of adjunct non-surgical therapeutic modalities.

Notes: None

Acknowledgements: None

Funding resources: None

Conflict of interest: The authors declare that there is no conflict of interest.