Key Points:
1. The current research is the first to present combined data concerning the alterations in structure and vascularisation of fPap with respect to the variations in EGM-thresholds in HNC patients when they are receiving radiochemotherapy as well as after the treatment.
2. Patients experience a deterioration in taste acuity when they are receiving radiochemotherapy and after the treatment.
3. Taste disorders associated with chemotherapy have a multifactorial aetiology.
4. There is not an improvement in EGM-thresholds concurrently with the morphology and vascularisation of fPap.
5. As a result of the limited number of studies, it is challenging to make suitable recommendations concerning diagnosis, therapy, and the expected development of taste deterioration in oncology environments.
Keywords: Contact endoscopy; radiochemotherapy; electrogustometry; fungiform papillae; vascularisation, taste.
Introduction
When chemotherapeutic (CT) drugs are systemically administered, this can frequently lead to serious acute adverse impacts. For instance, as a result of their cytotoxic effects and suppression of the immune system, patients may become more susceptible to oral mucositis and bleeding as well as a reduction or impairment of salivary gland function or oral infections [1,2]. Furthermore, as many as 89% of patients with head and neck cancer (HNC) experience taste dysfunction prior to being treated because of the malignancy [1].
After receiving radiation therapy (RT), alterations to taste could persist as a result of hyposalivation and damage to the cellular taste receptors [3]. A patient’s taste recovery after receiving treatment can vary between 2 and 6 months subsequent to oncologic therapy, although it may persist for an extended period [4,5].
Hence, this study aimed to evaluate the electrogustometric thresholds and related alterations of form in addition to the vascularisation of the tongue mucosa in patients with tonsillar squamous cell carcinoma and RCT.
Method
To reach this aim, a total of 20 patients with HNC receiving electrogustometry (EGM) treatment along with contact endoscopy were recruited (after obtaining approval from the local ethics committee as well as informed consent from all patients). In particular, EGM-thresholds, vascularisation of the end of the tongue, as well as fPap morphology were measured. Prior to starting the therapy, baseline (initial) measurements were made; subsequently, the second set of measurements were made after the initial CT had been completed, followed by the third measurements a week after the second CT cycle had been completed. Additionally, we scheduled follow-up measurements that would be performed in the 2nd and 4 months post-RCT. Every patient included in the evaluation received concurrent RCT (cisplatin, 5-FU) treatment as a result of the diagnosis of malignancy in the tonsils. The primary tumour was targeted with a dose of radiation varying between 50.4 Gy and 72 Gy. CT was delivered in 2 cycles (each with a duration of 1 week).
EGM was conducted according to previous reports using a single, flat, circular stainless-steel stimulus probe (with a diameter of 5mm) [6]. The device generates low-amplitude stimuli with a fixed time period (0.5, 1, 1.5, and 2 seconds). The output current is controlled by a feedback circuit where the error is < 1%. Measurements of the electric threshold scores were performed at six sites: the vallate papillae on either side of the tongue, innervated by the glossopharyngeal nerve, para-medially on either side of the tongue (both 2cm from the end), at an area innervated by the chorda tympani as well as the soft palace, innervated by the greater petrosal nerve bilaterally.
A non-contact method was firstly used to identify fPap. Subsequently, contact endoscopy was conducted utilising a 30° contact endoscope (magnification × 60 and × 150; Karl Storz, Tuttlingen, Germany). Patients were asked to rinse their mouth with water prior to the contact endoscopy. A contact method was firstly utilised with no staining in order to image the subepithelial vessels. Once the saliva had been carefully suctioned, the epithelia and taste pores were stained with methylene-blue 1% solution. A strip of filter paper covering an area of 1 cm2 was situated in a paramedian orientation on the tip of the tongue. Heat at the end of the endoscope was minimised using a cold source of light. CE examinations did not reveal any changes (increases of decreases) in vascularisation.
The fungiform papillae form was categorised into four different types in increasing order of damage: Type 1, (egg-shaped or long ellipse type – with no surface thickness), Type 2 (surface thickness is slightly more than Type 1), Type 3 (surface is thicker with increased irregularity), and Type 4 (surface is notably flat and shows signs of atrophy). It is important to note that papillae with a mushroom form and horned tips were categorised as filiform rather than fungiform papillae. As a result of their minimal level of staining, it was relatively easy to differentiate fungiform papillae from filiform papillae, as their staining was darker.
The morphology of the blood vessels at the end of the anterior tongue apex was classified based on the classification of Negoro et al. [7]. Five types of morphology were found for the vessels, categorised in increasing order of morphological changes: Type A (clear loop and wooden branch shape), Type B (clear loop and wooden branch shape), Type C (stretched blood vessels), Type D (dotted or granular shape), and Type E (unclear blood vessels).
For the purpose of statistical analysis, where it was not possible to measure the EGM-threshold, a numerical value of 36 dB was assigned. IBM® SPSS®Statistics 26.0 software was used and significance level was fixed at p < 0.05. STROBE statement was followed as reporting guideline for this study.
Results