Persistent infection with high -risk HPV genotypes has been identified as the most important aetiologic agent in the pathogenesis of cervical cancer [10]. Although, geographical variations in the prevalence of HPV DNA in cervical cancer biopsies, has been reported worldwide, the overall prevalence has been reported to be approximately 95% [11, 12]. In this cross-sectional study of women diagnosed with cervical cancer from 2013–2022, HPV prevalence was found to be 87% in the analysed cervical cancer tissues with HPV 16 genotype being the most frequent type detected (53.8%), followed by other HR-HPV genotype (17.3%), and HPV 18 genotype accounting for (15.4%) (Table 1). In addition, the combined prevalence of HPV 16 and 18 genotypes accounts for approximately 70% of the cervical cancer cases diagnosed in this study. However, a low HPV 16 carriage rate was observed in cervical swabs from reproductive aged women from Bah Camara et al (2018) study [8]. Their study identified other HR-HPV genotypes as the most common circulating type in urban Gambia. The high HPV prevalence rate of 87% found in this study is similar to other studies conducted in the neighbouring country, Senegal (90%, and in Nigeria (90.7%) [13, 14]. In addition, HPV studies carried out on FFPE samples in Malawi and South Africa also reported a high prevalence rate of 97% and 92%, respectively [15, 16]. However, countries including Poland and Iran reported a lower HPV prevalence rate in cervical cancer [17, 18]. These differences in HPV prevalence in cervical cancer could be attributed to several factors which may include geographical variations, quality and quantity of samples, sensitivity and specificity of the methods used for DNA extraction and HPV detection [19, 20].
The high prevalence (53%) of HPV16 reported in this FFPE study was consistent with other studies, as this genotype is the most prevalence type reported, globally [21, 22, 23, 24]. Epidemiological, clinical, and molecular studies have shown that HPV 16 and HPV18 genotypes are combinedly responsible for almost 70% of cervical cancers [25, 26]. The combined prevalence rate (approximately 70%) of HPV 16 (53.8%) and HPV 18 (15.4%) genotypes reported in this retrospective cross-sectional study corresponds to the estimate of the global distribution of these genotypes responsible for causing cervical cancers, worldwide. They are the most prevalent and most potent carcinogenic viruses, and their probability of disease progression and persistence is significantly higher than other high risk HPV genotypes [27]. Furthermore, in the 97 tissues diagnosed with squamous carcinoma, HPV 16 genotype accounts for 54.6% (53/97) (Table 1). This result agrees with that of Wall et al., carried out in the Gambia [9] and Missaoui et al., carried out in Tunisia, North Africa [28]. Both studies found that HPV 16 is the most frequent genotype among invasive squamous cell carcinomas. However, some studies have reported that other HR-HPV genotypes other than HPV 16 are most common HPV type detected in cervical cancer [29, 30]. A study carried out in Parakou, Benin Republic, reported that HPV 16 genotype was not detected in any of the cervical cancer cases, and HPV 39 was the most common genotype detected in their study [30]. This could be due to geographical variation and /or genotype specific replacement as 15% of cervical cancers are reported to be caused by other HR-HPV [31]
An observation in this study was the high proportion (17.3%) of single infections with other HR-HPV and (6.7%) combined infections of HPV 16 with other HR-HPV genotypes found in the cervical cancer tissue samples. This finding agrees with the result from Bah Camara et al., study that found other HR-HPV genotypes in cervical samples of HIV positive women diagnosed with cervical cancer in The Gambia [32]. Other studies have also shown that apart from HPV 16 and 18 genotypes, other HR-HPV genotypes that the quadrivalent HPV vaccine does not offer protection against causes cervical cancers [31]. Although, the Gambia is currently administering the quadrivalent vaccine which targets HPV genotypes 6, 11, 16 and 18, there is a need to switch to the nonavalent HPV vaccine which targets an additional 5 other HR-HPV genotypes (HPV 31, 33, 45, 52, and 58) which are associated of causing 15% of cervical cancers, globally [31].
HPV DNA negative results was found in 12.6% (15/119) histologically diagnosed cervical cancer cases. This could be due to the rare cases of non-HPV related cervical cancer or integration of the viral genome into the host chromosome, which could lead to changes in the
genes the PCR primers target.
Of the 326 cervical cancer cases histologically diagnosed in The Gambia, cervical cancer was most common in 43–53-year aged women (29.6%, 100/326). However, HPV related cervical cancer was more prevalent in the 32–42 year (28.8%, 30/104), followed by 43–53 year (27.9%, 29/104) aged women. This finding further shows that women that are mostly affected with cervical cancer in the Gambia are in their mid-adult lives (32–53 years) and possibly having young families. A significant association was found between cervical cancer diagnosis and age (P < 0.05) and HPV genotype (p < 0.05) (Table 2). The high (39%) HPV related cervical cancer observed in the Mandinka ethnic is not surprising as it is the most predominate ethnicity of the country. However, no significance association was found between HPV genotype, cervical cancer diagnoses and ethnicity. Another interesting finding from this study was that less histologically diagnosed cervical cancer cases was observed for the Northern, Central, and Upper Regions of the country compared to the Western (52%) and (32%) Kanifing Municipal Regions. These differences could be attributed to several factors among which include access, and proximity of the only histology department in the country, which is situated at the teaching hospital in Banjul, the capital city. The low (2%) prevalence rate of histologically diagnosed cervical cancer observed in the capital city could also be attributable to residents having access to early cervical cancer screening and pre cancer management, which is also offered in the teaching hospital in Banjul. This highlight the need to decentralise cervical cancer screening in the country for easy access and management of precancerous lesions, and prompt treatment options.