Application of F18-FDG PET in Evaluation of Betel Nut Associated Head and Neck Cancer

Introduction: Betel nut, also known as areca nut, is a common consumed substance in parts of South Asia, Africa, and the Asia Pacific. It is commonly chewed with betel leaves (paan) or with tobacco (betel quid). It is estimated that up to 10% of the population connsumes this substance, making it the 4th most widely used addictive substance behind nicotine, alcohol, and caffeine. Betel nut is carcinogenic and its consumption along with tobacco is strongly associated with squamous cell carcinoma (SCC) of the oral cavity. While less common in the United States, Betel nut use remains an underrecognized risk factor in certain populations. Due to our unique referral population we present our clinical experience in utilizing PET FDG scans in advanced Betel nut associated oral cancers.

Methods: A retrospective review was performed from 2020-2022 to identify patients with Betel nut use and squamous cell carcinoma of the oral cavity. There were 38 patients identified. The vast majority of the patients were from the Pacific Islands, specifically Saipan and Guam. Of the 38 patients, 19 had an 18F-FDG PET/CT scan during their treatment course. Of the 19 patients, 9 patients had a 18F-FDG PET/CT scan prior to surgery and 10 patients had post-treatment 18F-FDG PET/CT scans. Of the 19 patients, 12 patients underwent surgery and had correlative pathology reports. Surgical documentation, pathology reports, PET/CT reports were correlated and descriptive statistics tabulated.

Results: The mean age for our population was 47.8 and the median age is 44, which is younger than the average of 58 for oral cancers in general. Approximately 63% were male, roughly consistent with approximately 69% as seen in the literature. In addition to betel nut use, approximately 84.2% demonstrated additional risk factors, such lime use, tobacco use, alcohol use, and/or smoking. Of those that underwent surgery and had associated pathology reports (n=12), the distribution of pathology was 17% well differentiated SCC (n=2), 58% moderately differentiated SCC (n=7), and 25% poorly differentiated SCC (n=3), consistent with distributions of pathology of oral cavity SCC seen in the literature. Of the note, the distribution of site lesions is 69% (n=13) along the buccal/cheek/alveolar mucosa, 26% on the tongue (n = 5), and 5% (n = 1) on the soft palate. There is greater than expected buccal lesions compared to the literature, which may be related to mechanism of consumption. Of those who underwent surgery and had associated pathology (n=12), about 50% had surgically proven local metastasis. The average max SUV of the primary lesion was 24.6, while the average max SUV of proven metastasis was 9.0 (range 4.7-18.8). When looking at max SUV values by pathology, the degree of differentiation appears to correlate with SUV values (average max SUV of well differentiated lesions 14.7, moderately differentiated 22.8, and poorly differentiated 29.2).

Conclusions: Betel nut is an underrecognized but significant risk factor in certain populations. Patients with betel nut associated SCC are younger than the average patient with oral cancer. While the distribution of lesion differentiation is similar to what is seen in overall oral cancers, the distribution of site of disease favoring the buccal/alveolar mucosa in these patients may be related to the method consumption. Although the number of patients is small in this retrospective review, there appears to be a positive association between the degree of differentiation and max SUV on 18F FDG PET/CT, which should be explored further. Additionally, both primary and metastastic lesions appear to be reliably seen with 18F FDG PET/CT suggesting that it is an effective tool for imaging betel nut associated SCC.

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